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#1
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CD Level Variations
I'm sure many of you have experienced the frustration in different playback levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. Some of you may remember during 45 RPM record days that the same problem existed. Columbia 45s tended to be louder than other labels. I would have thought that standards would have been tighter with the introduction of the Compact Disc. All of this is with 2-channel stereo. Just imagine how well recording engineers will maintain uniformity with 5.1, 6.1, 7.1, ......., n.1. Oh well, enjoy the music as best as you can :~) |
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#2
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CD Level Variations
I'm sure many of you have experienced the frustration in different playback
levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. The compression is often so great that there are two very negative side effects: - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. In effect, modern hyper-compressed music is using only a small fraction of the dynamic range of the CD medium. You could probably requantize this sort of music to 12 bits, or even less, and not be able to hear the difference. Older releases were often done with a more conservative (and, I think, much saner) ethic: keep the signal a safe distance away from digital full-scale, *never* clip the signal, and retain a natural-sounding dynamic range in the music. This results in a lower-overall sound level, and by comparison with modern CDs these older ones tend to sound "weak" at the same volume-control level. I understand that CD mastering facilities used to pre-check digital masters, and reject them if there were any "overs". These days, it's common to find top-name CDs which are full of digital clipping. I personally find the result to be rather horrid. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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#3
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CD Level Variations
I'm sure many of you have experienced the frustration in different playback
levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. The compression is often so great that there are two very negative side effects: - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. In effect, modern hyper-compressed music is using only a small fraction of the dynamic range of the CD medium. You could probably requantize this sort of music to 12 bits, or even less, and not be able to hear the difference. Older releases were often done with a more conservative (and, I think, much saner) ethic: keep the signal a safe distance away from digital full-scale, *never* clip the signal, and retain a natural-sounding dynamic range in the music. This results in a lower-overall sound level, and by comparison with modern CDs these older ones tend to sound "weak" at the same volume-control level. I understand that CD mastering facilities used to pre-check digital masters, and reject them if there were any "overs". These days, it's common to find top-name CDs which are full of digital clipping. I personally find the result to be rather horrid. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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#4
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CD Level Variations
I'm sure many of you have experienced the frustration in different playback
levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. The compression is often so great that there are two very negative side effects: - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. In effect, modern hyper-compressed music is using only a small fraction of the dynamic range of the CD medium. You could probably requantize this sort of music to 12 bits, or even less, and not be able to hear the difference. Older releases were often done with a more conservative (and, I think, much saner) ethic: keep the signal a safe distance away from digital full-scale, *never* clip the signal, and retain a natural-sounding dynamic range in the music. This results in a lower-overall sound level, and by comparison with modern CDs these older ones tend to sound "weak" at the same volume-control level. I understand that CD mastering facilities used to pre-check digital masters, and reject them if there were any "overs". These days, it's common to find top-name CDs which are full of digital clipping. I personally find the result to be rather horrid. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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#5
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CD Level Variations
I'm sure many of you have experienced the frustration in different playback
levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. The compression is often so great that there are two very negative side effects: - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. In effect, modern hyper-compressed music is using only a small fraction of the dynamic range of the CD medium. You could probably requantize this sort of music to 12 bits, or even less, and not be able to hear the difference. Older releases were often done with a more conservative (and, I think, much saner) ethic: keep the signal a safe distance away from digital full-scale, *never* clip the signal, and retain a natural-sounding dynamic range in the music. This results in a lower-overall sound level, and by comparison with modern CDs these older ones tend to sound "weak" at the same volume-control level. I understand that CD mastering facilities used to pre-check digital masters, and reject them if there were any "overs". These days, it's common to find top-name CDs which are full of digital clipping. I personally find the result to be rather horrid. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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#6
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CD Level Variations
Dave,
You raise some good points and I think the marketing thing has existed for years. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. I believe the above is what I had in mind. There was a marketing approach as far as time capacity. The compression is often so great that there are two very negative side effects: I don't want to get into a vinyl/CD arguement but, I believe Kunzel's recording of Tchaikovsky's 1812 Overture on Telarc (the first one) was more stunning on record than the early CD. Compression may have been present in this case. - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. In effect, modern hyper-compressed music is using only a small fraction of the dynamic range of the CD medium. You could probably requantize this sort of music to 12 bits, or even less, and not be able to hear the difference. Some of this may depend on the music to which one listens. Older releases were often done with a more conservative (and, I think, much saner) ethic: keep the signal a safe distance away from digital full-scale, *never* clip the signal, and retain a natural-sounding dynamic range in the music. I don't necessarily disagree with the above. This results in a lower-overall sound level, and by comparison with modern CDs these older ones tend to sound "weak" at the same volume-control level. I understand that CD mastering facilities used to pre-check digital masters, and reject them if there were any "overs". These days, it's common to find top-name CDs which are full of digital clipping. I personally find the result to be rather horrid. Was there ever a "level" standard with CDs? Since it's digital, one would think it is more controllable. |
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#7
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CD Level Variations
Dave,
You raise some good points and I think the marketing thing has existed for years. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. I believe the above is what I had in mind. There was a marketing approach as far as time capacity. The compression is often so great that there are two very negative side effects: I don't want to get into a vinyl/CD arguement but, I believe Kunzel's recording of Tchaikovsky's 1812 Overture on Telarc (the first one) was more stunning on record than the early CD. Compression may have been present in this case. - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. In effect, modern hyper-compressed music is using only a small fraction of the dynamic range of the CD medium. You could probably requantize this sort of music to 12 bits, or even less, and not be able to hear the difference. Some of this may depend on the music to which one listens. Older releases were often done with a more conservative (and, I think, much saner) ethic: keep the signal a safe distance away from digital full-scale, *never* clip the signal, and retain a natural-sounding dynamic range in the music. I don't necessarily disagree with the above. This results in a lower-overall sound level, and by comparison with modern CDs these older ones tend to sound "weak" at the same volume-control level. I understand that CD mastering facilities used to pre-check digital masters, and reject them if there were any "overs". These days, it's common to find top-name CDs which are full of digital clipping. I personally find the result to be rather horrid. Was there ever a "level" standard with CDs? Since it's digital, one would think it is more controllable. |
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#8
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CD Level Variations
Dave,
You raise some good points and I think the marketing thing has existed for years. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. I believe the above is what I had in mind. There was a marketing approach as far as time capacity. The compression is often so great that there are two very negative side effects: I don't want to get into a vinyl/CD arguement but, I believe Kunzel's recording of Tchaikovsky's 1812 Overture on Telarc (the first one) was more stunning on record than the early CD. Compression may have been present in this case. - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. In effect, modern hyper-compressed music is using only a small fraction of the dynamic range of the CD medium. You could probably requantize this sort of music to 12 bits, or even less, and not be able to hear the difference. Some of this may depend on the music to which one listens. Older releases were often done with a more conservative (and, I think, much saner) ethic: keep the signal a safe distance away from digital full-scale, *never* clip the signal, and retain a natural-sounding dynamic range in the music. I don't necessarily disagree with the above. This results in a lower-overall sound level, and by comparison with modern CDs these older ones tend to sound "weak" at the same volume-control level. I understand that CD mastering facilities used to pre-check digital masters, and reject them if there were any "overs". These days, it's common to find top-name CDs which are full of digital clipping. I personally find the result to be rather horrid. Was there ever a "level" standard with CDs? Since it's digital, one would think it is more controllable. |
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#9
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CD Level Variations
Dave,
You raise some good points and I think the marketing thing has existed for years. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. I believe the above is what I had in mind. There was a marketing approach as far as time capacity. The compression is often so great that there are two very negative side effects: I don't want to get into a vinyl/CD arguement but, I believe Kunzel's recording of Tchaikovsky's 1812 Overture on Telarc (the first one) was more stunning on record than the early CD. Compression may have been present in this case. - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. In effect, modern hyper-compressed music is using only a small fraction of the dynamic range of the CD medium. You could probably requantize this sort of music to 12 bits, or even less, and not be able to hear the difference. Some of this may depend on the music to which one listens. Older releases were often done with a more conservative (and, I think, much saner) ethic: keep the signal a safe distance away from digital full-scale, *never* clip the signal, and retain a natural-sounding dynamic range in the music. I don't necessarily disagree with the above. This results in a lower-overall sound level, and by comparison with modern CDs these older ones tend to sound "weak" at the same volume-control level. I understand that CD mastering facilities used to pre-check digital masters, and reject them if there were any "overs". These days, it's common to find top-name CDs which are full of digital clipping. I personally find the result to be rather horrid. Was there ever a "level" standard with CDs? Since it's digital, one would think it is more controllable. |
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#10
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CD Level Variations
Was there ever a "level" standard with CDs? Since it's digital, one would think it is more controllable. There is a level standard: 0dB is full scale. Without a lot of processing and other stuff, a careful engineer would record with an average program level of -20dB (using a VU meter). However, recording is rarely done direct to CD, so even if the original recording was done at -20dB, after the final mix-down and mastering, the signal is most likely "normalized" so that the signal hits 0dB (so as to use all the bits) for at least one point in the finished CD. If the master is heavily compressed or peak-limited, the average program level might then be -5dB, while the average program level a classical CD might be -10dB or -20dB on loud passages. The digital signal is quite controllable, but they're not controlling it for uniform loudness on your jukebox, they're controlling it for the artistic, marketing and technical qualities of the given CD as a stand-alone product. |
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#11
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CD Level Variations
Was there ever a "level" standard with CDs? Since it's digital, one would think it is more controllable. There is a level standard: 0dB is full scale. Without a lot of processing and other stuff, a careful engineer would record with an average program level of -20dB (using a VU meter). However, recording is rarely done direct to CD, so even if the original recording was done at -20dB, after the final mix-down and mastering, the signal is most likely "normalized" so that the signal hits 0dB (so as to use all the bits) for at least one point in the finished CD. If the master is heavily compressed or peak-limited, the average program level might then be -5dB, while the average program level a classical CD might be -10dB or -20dB on loud passages. The digital signal is quite controllable, but they're not controlling it for uniform loudness on your jukebox, they're controlling it for the artistic, marketing and technical qualities of the given CD as a stand-alone product. |
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#12
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CD Level Variations
Was there ever a "level" standard with CDs? Since it's digital, one would think it is more controllable. There is a level standard: 0dB is full scale. Without a lot of processing and other stuff, a careful engineer would record with an average program level of -20dB (using a VU meter). However, recording is rarely done direct to CD, so even if the original recording was done at -20dB, after the final mix-down and mastering, the signal is most likely "normalized" so that the signal hits 0dB (so as to use all the bits) for at least one point in the finished CD. If the master is heavily compressed or peak-limited, the average program level might then be -5dB, while the average program level a classical CD might be -10dB or -20dB on loud passages. The digital signal is quite controllable, but they're not controlling it for uniform loudness on your jukebox, they're controlling it for the artistic, marketing and technical qualities of the given CD as a stand-alone product. |
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#13
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CD Level Variations
Was there ever a "level" standard with CDs? Since it's digital, one would think it is more controllable. There is a level standard: 0dB is full scale. Without a lot of processing and other stuff, a careful engineer would record with an average program level of -20dB (using a VU meter). However, recording is rarely done direct to CD, so even if the original recording was done at -20dB, after the final mix-down and mastering, the signal is most likely "normalized" so that the signal hits 0dB (so as to use all the bits) for at least one point in the finished CD. If the master is heavily compressed or peak-limited, the average program level might then be -5dB, while the average program level a classical CD might be -10dB or -20dB on loud passages. The digital signal is quite controllable, but they're not controlling it for uniform loudness on your jukebox, they're controlling it for the artistic, marketing and technical qualities of the given CD as a stand-alone product. |
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#15
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CD Level Variations
In , on 03/15/04
at 10:29 PM, (Dave Platt) said: [ ... ] - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. [ ... ] I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. That said, I saw lots of early players that would clip my full level test disc, modern players don't clip that disc. I also saw receivers and amplifiers that could not handle a full level signal (often 2 volts) from a CD player, modern or not. It amused and shocked me that respected reviewers neglected to mention that some CD players clipped the full level signal. Years later, after the problem went away, one reviewer was confronted with this issue and replied that he thought reporting the (very common) problem would have slowed the growth of CD (he claimed that full levels on music CD's were not common). That revelation, while it made me feel better, knowing that he at least could measure and correctly interpret the measurements, also clearly told me that the reviewers were not looking out for the customer. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
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#16
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CD Level Variations
In , on 03/15/04
at 10:29 PM, (Dave Platt) said: [ ... ] - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. [ ... ] I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. That said, I saw lots of early players that would clip my full level test disc, modern players don't clip that disc. I also saw receivers and amplifiers that could not handle a full level signal (often 2 volts) from a CD player, modern or not. It amused and shocked me that respected reviewers neglected to mention that some CD players clipped the full level signal. Years later, after the problem went away, one reviewer was confronted with this issue and replied that he thought reporting the (very common) problem would have slowed the growth of CD (he claimed that full levels on music CD's were not common). That revelation, while it made me feel better, knowing that he at least could measure and correctly interpret the measurements, also clearly told me that the reviewers were not looking out for the customer. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
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#17
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CD Level Variations
In , on 03/15/04
at 10:29 PM, (Dave Platt) said: [ ... ] - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. [ ... ] I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. That said, I saw lots of early players that would clip my full level test disc, modern players don't clip that disc. I also saw receivers and amplifiers that could not handle a full level signal (often 2 volts) from a CD player, modern or not. It amused and shocked me that respected reviewers neglected to mention that some CD players clipped the full level signal. Years later, after the problem went away, one reviewer was confronted with this issue and replied that he thought reporting the (very common) problem would have slowed the growth of CD (he claimed that full levels on music CD's were not common). That revelation, while it made me feel better, knowing that he at least could measure and correctly interpret the measurements, also clearly told me that the reviewers were not looking out for the customer. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
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#18
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CD Level Variations
In article ,
Barry Mann wrote: - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. Touching the limit, for a single sample, usually doesn't cause technical problems. Two or more samples, touching the limit, usually means that the original signal tried to go past the limit, and has in fact been clipped. I believe that the usual working definition of a "digital over" is two or more consecutive samples at the positive or negative limit. Leaving a small fraction of a dB of digital headroom seems like good practice, because (as you note) some CD players will show clipping artifacts at the digital limit, and I understand that some can actually show clipping problems even if the limit isn't reached. CD players with digital oversampling filters (many/most of 'em) can have problems with clipping during the oversampling process - even if two adjacent samples in the original 16-bit data stream are below the limit, the reconstructed/oversampled waveform calculated by the filters can go over the limit and be clipped. When I dub LPs to CD-R, I try to keep the loudest peaks at least a dB or so below full-scale, and I don't feel bad if a particularly quiet LP never reaches 1/2 of full scale (6 dB down from the limit). With about 92 dB of dynamic range, a few dB at the hot end simply isn't an issue for most program material. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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#19
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CD Level Variations
In article ,
Barry Mann wrote: - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. Touching the limit, for a single sample, usually doesn't cause technical problems. Two or more samples, touching the limit, usually means that the original signal tried to go past the limit, and has in fact been clipped. I believe that the usual working definition of a "digital over" is two or more consecutive samples at the positive or negative limit. Leaving a small fraction of a dB of digital headroom seems like good practice, because (as you note) some CD players will show clipping artifacts at the digital limit, and I understand that some can actually show clipping problems even if the limit isn't reached. CD players with digital oversampling filters (many/most of 'em) can have problems with clipping during the oversampling process - even if two adjacent samples in the original 16-bit data stream are below the limit, the reconstructed/oversampled waveform calculated by the filters can go over the limit and be clipped. When I dub LPs to CD-R, I try to keep the loudest peaks at least a dB or so below full-scale, and I don't feel bad if a particularly quiet LP never reaches 1/2 of full scale (6 dB down from the limit). With about 92 dB of dynamic range, a few dB at the hot end simply isn't an issue for most program material. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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#20
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CD Level Variations
In article ,
Barry Mann wrote: - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. Touching the limit, for a single sample, usually doesn't cause technical problems. Two or more samples, touching the limit, usually means that the original signal tried to go past the limit, and has in fact been clipped. I believe that the usual working definition of a "digital over" is two or more consecutive samples at the positive or negative limit. Leaving a small fraction of a dB of digital headroom seems like good practice, because (as you note) some CD players will show clipping artifacts at the digital limit, and I understand that some can actually show clipping problems even if the limit isn't reached. CD players with digital oversampling filters (many/most of 'em) can have problems with clipping during the oversampling process - even if two adjacent samples in the original 16-bit data stream are below the limit, the reconstructed/oversampled waveform calculated by the filters can go over the limit and be clipped. When I dub LPs to CD-R, I try to keep the loudest peaks at least a dB or so below full-scale, and I don't feel bad if a particularly quiet LP never reaches 1/2 of full scale (6 dB down from the limit). With about 92 dB of dynamic range, a few dB at the hot end simply isn't an issue for most program material. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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#21
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CD Level Variations
In article ,
Barry Mann wrote: - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. Touching the limit, for a single sample, usually doesn't cause technical problems. Two or more samples, touching the limit, usually means that the original signal tried to go past the limit, and has in fact been clipped. I believe that the usual working definition of a "digital over" is two or more consecutive samples at the positive or negative limit. Leaving a small fraction of a dB of digital headroom seems like good practice, because (as you note) some CD players will show clipping artifacts at the digital limit, and I understand that some can actually show clipping problems even if the limit isn't reached. CD players with digital oversampling filters (many/most of 'em) can have problems with clipping during the oversampling process - even if two adjacent samples in the original 16-bit data stream are below the limit, the reconstructed/oversampled waveform calculated by the filters can go over the limit and be clipped. When I dub LPs to CD-R, I try to keep the loudest peaks at least a dB or so below full-scale, and I don't feel bad if a particularly quiet LP never reaches 1/2 of full scale (6 dB down from the limit). With about 92 dB of dynamic range, a few dB at the hot end simply isn't an issue for most program material. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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#22
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CD Level Variations
I'm sure many of you have experienced the frustration in different playback levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. Some of you may remember during 45 RPM record days that the same problem existed. Columbia 45s tended to be louder than other labels. I would have thought that standards would have been tighter with the introduction of the Compact Disc. All of this is with 2-channel stereo. Just imagine how well recording engineers will maintain uniformity with 5.1, 6.1, 7.1, ......., n.1. Oh well, enjoy the music as best as you can :~) The problem is that the loudness wars have gotten worse with digital processing. Those loud cd's have been processed into ear fatiguing mush rather than leaving the dynamic range of music intact. The only thing that one can do to even the volume differences is to use leveling compressors to further process the sound. This will turn down the loud stuff and bring up the level of the low sounds. Then everything will sound like crap, not just the loud overly processed CD's Richard H. Kuschel "I canna change the law of physics."-----Scotty |
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#23
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CD Level Variations
I'm sure many of you have experienced the frustration in different playback levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. Some of you may remember during 45 RPM record days that the same problem existed. Columbia 45s tended to be louder than other labels. I would have thought that standards would have been tighter with the introduction of the Compact Disc. All of this is with 2-channel stereo. Just imagine how well recording engineers will maintain uniformity with 5.1, 6.1, 7.1, ......., n.1. Oh well, enjoy the music as best as you can :~) The problem is that the loudness wars have gotten worse with digital processing. Those loud cd's have been processed into ear fatiguing mush rather than leaving the dynamic range of music intact. The only thing that one can do to even the volume differences is to use leveling compressors to further process the sound. This will turn down the loud stuff and bring up the level of the low sounds. Then everything will sound like crap, not just the loud overly processed CD's Richard H. Kuschel "I canna change the law of physics."-----Scotty |
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#24
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CD Level Variations
I'm sure many of you have experienced the frustration in different playback levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. Some of you may remember during 45 RPM record days that the same problem existed. Columbia 45s tended to be louder than other labels. I would have thought that standards would have been tighter with the introduction of the Compact Disc. All of this is with 2-channel stereo. Just imagine how well recording engineers will maintain uniformity with 5.1, 6.1, 7.1, ......., n.1. Oh well, enjoy the music as best as you can :~) The problem is that the loudness wars have gotten worse with digital processing. Those loud cd's have been processed into ear fatiguing mush rather than leaving the dynamic range of music intact. The only thing that one can do to even the volume differences is to use leveling compressors to further process the sound. This will turn down the loud stuff and bring up the level of the low sounds. Then everything will sound like crap, not just the loud overly processed CD's Richard H. Kuschel "I canna change the law of physics."-----Scotty |
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#25
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CD Level Variations
I'm sure many of you have experienced the frustration in different playback levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. Some of you may remember during 45 RPM record days that the same problem existed. Columbia 45s tended to be louder than other labels. I would have thought that standards would have been tighter with the introduction of the Compact Disc. All of this is with 2-channel stereo. Just imagine how well recording engineers will maintain uniformity with 5.1, 6.1, 7.1, ......., n.1. Oh well, enjoy the music as best as you can :~) The problem is that the loudness wars have gotten worse with digital processing. Those loud cd's have been processed into ear fatiguing mush rather than leaving the dynamic range of music intact. The only thing that one can do to even the volume differences is to use leveling compressors to further process the sound. This will turn down the loud stuff and bring up the level of the low sounds. Then everything will sound like crap, not just the loud overly processed CD's Richard H. Kuschel "I canna change the law of physics."-----Scotty |
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#26
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CD Level Variations
"Dave Platt" wrote in message ... In article , Barry Mann wrote: - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. Touching the limit, for a single sample, usually doesn't cause technical problems. Two or more samples, touching the limit, usually means that the original signal tried to go past the limit, and has in fact been clipped. I believe that the usual working definition of a "digital over" is two or more consecutive samples at the positive or negative limit. Leaving a small fraction of a dB of digital headroom seems like good practice, because (as you note) some CD players will show clipping artifacts at the digital limit, and I understand that some can actually show clipping problems even if the limit isn't reached. CD players with digital oversampling filters (many/most of 'em) can have problems with clipping during the oversampling process - even if two adjacent samples in the original 16-bit data stream are below the limit, the reconstructed/oversampled waveform calculated by the filters can go over the limit and be clipped. When I dub LPs to CD-R, I try to keep the loudest peaks at least a dB or so below full-scale, and I don't feel bad if a particularly quiet LP never reaches 1/2 of full scale (6 dB down from the limit). With about 92 dB of dynamic range, a few dB at the hot end simply isn't an issue for most program material. While we are at the subject of dbs in CD, I have a dumb question. I understand that Cd range is 96 db with 16 bit depth and each bit represents 6 db. When I see a wav file from a CD on a wave editor such as Goldwave, I see a wave with postive and negative y axis values ( 1 to -1) with 0 being silence. How does it 96 db range map here. What confuses me is that people call 0 db as the full range and other valeus being -20db and so on; how do these amplitude map to wav I see. |
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#27
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CD Level Variations
"Dave Platt" wrote in message ... In article , Barry Mann wrote: - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. Touching the limit, for a single sample, usually doesn't cause technical problems. Two or more samples, touching the limit, usually means that the original signal tried to go past the limit, and has in fact been clipped. I believe that the usual working definition of a "digital over" is two or more consecutive samples at the positive or negative limit. Leaving a small fraction of a dB of digital headroom seems like good practice, because (as you note) some CD players will show clipping artifacts at the digital limit, and I understand that some can actually show clipping problems even if the limit isn't reached. CD players with digital oversampling filters (many/most of 'em) can have problems with clipping during the oversampling process - even if two adjacent samples in the original 16-bit data stream are below the limit, the reconstructed/oversampled waveform calculated by the filters can go over the limit and be clipped. When I dub LPs to CD-R, I try to keep the loudest peaks at least a dB or so below full-scale, and I don't feel bad if a particularly quiet LP never reaches 1/2 of full scale (6 dB down from the limit). With about 92 dB of dynamic range, a few dB at the hot end simply isn't an issue for most program material. While we are at the subject of dbs in CD, I have a dumb question. I understand that Cd range is 96 db with 16 bit depth and each bit represents 6 db. When I see a wav file from a CD on a wave editor such as Goldwave, I see a wave with postive and negative y axis values ( 1 to -1) with 0 being silence. How does it 96 db range map here. What confuses me is that people call 0 db as the full range and other valeus being -20db and so on; how do these amplitude map to wav I see. |
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#28
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CD Level Variations
"Dave Platt" wrote in message ... In article , Barry Mann wrote: - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. Touching the limit, for a single sample, usually doesn't cause technical problems. Two or more samples, touching the limit, usually means that the original signal tried to go past the limit, and has in fact been clipped. I believe that the usual working definition of a "digital over" is two or more consecutive samples at the positive or negative limit. Leaving a small fraction of a dB of digital headroom seems like good practice, because (as you note) some CD players will show clipping artifacts at the digital limit, and I understand that some can actually show clipping problems even if the limit isn't reached. CD players with digital oversampling filters (many/most of 'em) can have problems with clipping during the oversampling process - even if two adjacent samples in the original 16-bit data stream are below the limit, the reconstructed/oversampled waveform calculated by the filters can go over the limit and be clipped. When I dub LPs to CD-R, I try to keep the loudest peaks at least a dB or so below full-scale, and I don't feel bad if a particularly quiet LP never reaches 1/2 of full scale (6 dB down from the limit). With about 92 dB of dynamic range, a few dB at the hot end simply isn't an issue for most program material. While we are at the subject of dbs in CD, I have a dumb question. I understand that Cd range is 96 db with 16 bit depth and each bit represents 6 db. When I see a wav file from a CD on a wave editor such as Goldwave, I see a wave with postive and negative y axis values ( 1 to -1) with 0 being silence. How does it 96 db range map here. What confuses me is that people call 0 db as the full range and other valeus being -20db and so on; how do these amplitude map to wav I see. |
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#29
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CD Level Variations
"Dave Platt" wrote in message ... In article , Barry Mann wrote: - The sound is often pushed to such a high volume level that it's hitting the maximum-positive/negative number boundaries of the 16-bit digital number system used by CDs. In other words, it's clipping - quite hard, often very harshly, and often for a prolonged period. I don't have a problem with the CD touching the top level at one or more spots. This is good management of dynamic range. It's just a simple computer trick to do this. Redbook CD's have a 16 bit range. "Clipping" implies a loss of information because the signal would have gone beyond the limit if it could have. "Touching" means the signal reached the limit and didn't need to go past it. Touching the limit, for a single sample, usually doesn't cause technical problems. Two or more samples, touching the limit, usually means that the original signal tried to go past the limit, and has in fact been clipped. I believe that the usual working definition of a "digital over" is two or more consecutive samples at the positive or negative limit. Leaving a small fraction of a dB of digital headroom seems like good practice, because (as you note) some CD players will show clipping artifacts at the digital limit, and I understand that some can actually show clipping problems even if the limit isn't reached. CD players with digital oversampling filters (many/most of 'em) can have problems with clipping during the oversampling process - even if two adjacent samples in the original 16-bit data stream are below the limit, the reconstructed/oversampled waveform calculated by the filters can go over the limit and be clipped. When I dub LPs to CD-R, I try to keep the loudest peaks at least a dB or so below full-scale, and I don't feel bad if a particularly quiet LP never reaches 1/2 of full scale (6 dB down from the limit). With about 92 dB of dynamic range, a few dB at the hot end simply isn't an issue for most program material. While we are at the subject of dbs in CD, I have a dumb question. I understand that Cd range is 96 db with 16 bit depth and each bit represents 6 db. When I see a wav file from a CD on a wave editor such as Goldwave, I see a wave with postive and negative y axis values ( 1 to -1) with 0 being silence. How does it 96 db range map here. What confuses me is that people call 0 db as the full range and other valeus being -20db and so on; how do these amplitude map to wav I see. |
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#30
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CD Level Variations
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#31
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CD Level Variations
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#32
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CD Level Variations
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#33
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#34
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CD Level Variations
In , on 03/16/04
at 11:19 PM, "Bubba" said: [ ... ] While we are at the subject of dbs in CD, I have a dumb question. I understand that Cd range is 96 db with 16 bit depth and each bit represents 6 db. When I see a wav file from a CD on a wave editor such as Goldwave, I see a wave with postive and negative y axis values ( 1 to -1) with 0 being silence. How does it 96 db range map here. What confuses me is that people call 0 db as the full range and other valeus being -20db and so on; how do these amplitude map to wav I see. There are several concepts mixed together above. dB is a relative scale. "0" is the reference. For example, if I ask you, "how high is that picture?", when we are standing in your bedroom, you might say, "8 feet". In this situation the "0" foot reference is implied to be the floor we are standing on, however, we could be standing on the 10th floor of a building that is 2000 feet above sea level. (and, of course, we are at a certain distance from our sun and other celestial bodies.) Without some sort of implied or stated reference and some units of measure, the "8" is a meaningless number. (In other countries "8" could mean 8 meters -- a rather elegant bedroom) There is a tendancy in the audio industry for us to be somewhat sloppy with our dB's. We neglect to state our reference and the units of our measure. We are just lazy. Many times we are working within some sort of context and the reference and units are implied by the conventions of the situation. The real experts are always careful to state their reference and units. The half experts just sling a dB at you, and you must nod and smile to make them, and anyone else in the room, think that you understood their half sense. --- It is customary to peg "0" at the usual (in some context) maximum value. Without getting into some math that you probably have been ducking since highschool, I can't easily explain why, but A dB value that is negative implies a value that is less than the reference. A dB reference above zero implies greater (louder, in an audio context) than the reference. Exactly what happens when a signal goes above zero depends on the context. For example, if "0" is defined as "as loud as you can play your stereo before the neighbors can hear it", then +10 could result in a phone call, the police, or "Vito" banging on your door. If you go to +10 on a tape recorder, you will probably experience some distortion, but there will be no physical damage. This is why -90 on a dB calibrated volume knob is rather quiet and zero is rather loud. Sometimes you'll see minus infinity just below -90. This is another way to say "off". ---- Without knowing exactly which display you are observing, I can't say exactly what the +1 to -1 scale means (and it really doesn't matter). Most likely it is an arbitrary scale on a display of the instantaneous voltage vs time graph of the music. "+1" or "-1" would represent the maximum value before distortion begins. !! How could "-1" be a maximum? !! Sound is movement of air. Think of the vibrating membrane on a drum. As it bulges out a small increase (relative to ambient pressure) in pressure occurs. For the sake of this discussion we will assign "+" values to an outward bulge. As it bulges in, there is a small decrease in pressure. We will assign these "-" values. These pressure changes travel to your ear and cause your eardrum to move and, after some processing in your brain, you perceive the sound. The out and in bulges tend to be symmetric and we could assign "+1" and "-1" to represent the maximum in and out excursion possible before the membrane suffers terminal trauma. Your sound editing program displays the analog version of the signal so that you can identify exactly when a particular sound ends. Editing is usually more pleasant if the cuts occur at silent instants -- the zero crossings between musical notes. --- Assigning dB values to that -1 point on you computer program's graph is problematic. We don't need to dig into this particular problem, but there is another math issue that you are probably familiar with. 2*2 is two squared. The square root of four is two. The "square root" process finds a number that when squared (multiplying the number by itself), results in the square. Calculating the square root of minus four is a problem. Although a bit more obscure, there is a problem expressing the negative values on your scale in a dB context -- and there is no need to. My point is that your +1 to -1 display does not easily map to anything dB. --- 16 bits implies 65536 different values. If we define our "0dB" reference as the loudest sound that can be stored on the CD format, then the quietest sound could be represented as -96dB. Certainly, there could be quieter sounds in the studio, they just can't be represented on a CD. (Many processes have little problems like this. For example, the dollar currency system has no mechanism to represent fractional cents.) Other than possibly getting some credit on a trick question on an exam, there is no benefit to doing this, but you could replace "+1" on your display with "0dB", "-1" with "0dB" and "0" with "-96db". This is not a good idea, but I though it might help you understand the concepts better. In my college career, if faced with such an exam question, I probably would not have answered this question correctly, and it would have upset me so much that I may not have been able to concentrate on the remainder of the test. Later, I would have tracked down and had words with the person who fabricated the question because it offends one's sense of good practice. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
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#35
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CD Level Variations
In , on 03/16/04
at 11:19 PM, "Bubba" said: [ ... ] While we are at the subject of dbs in CD, I have a dumb question. I understand that Cd range is 96 db with 16 bit depth and each bit represents 6 db. When I see a wav file from a CD on a wave editor such as Goldwave, I see a wave with postive and negative y axis values ( 1 to -1) with 0 being silence. How does it 96 db range map here. What confuses me is that people call 0 db as the full range and other valeus being -20db and so on; how do these amplitude map to wav I see. There are several concepts mixed together above. dB is a relative scale. "0" is the reference. For example, if I ask you, "how high is that picture?", when we are standing in your bedroom, you might say, "8 feet". In this situation the "0" foot reference is implied to be the floor we are standing on, however, we could be standing on the 10th floor of a building that is 2000 feet above sea level. (and, of course, we are at a certain distance from our sun and other celestial bodies.) Without some sort of implied or stated reference and some units of measure, the "8" is a meaningless number. (In other countries "8" could mean 8 meters -- a rather elegant bedroom) There is a tendancy in the audio industry for us to be somewhat sloppy with our dB's. We neglect to state our reference and the units of our measure. We are just lazy. Many times we are working within some sort of context and the reference and units are implied by the conventions of the situation. The real experts are always careful to state their reference and units. The half experts just sling a dB at you, and you must nod and smile to make them, and anyone else in the room, think that you understood their half sense. --- It is customary to peg "0" at the usual (in some context) maximum value. Without getting into some math that you probably have been ducking since highschool, I can't easily explain why, but A dB value that is negative implies a value that is less than the reference. A dB reference above zero implies greater (louder, in an audio context) than the reference. Exactly what happens when a signal goes above zero depends on the context. For example, if "0" is defined as "as loud as you can play your stereo before the neighbors can hear it", then +10 could result in a phone call, the police, or "Vito" banging on your door. If you go to +10 on a tape recorder, you will probably experience some distortion, but there will be no physical damage. This is why -90 on a dB calibrated volume knob is rather quiet and zero is rather loud. Sometimes you'll see minus infinity just below -90. This is another way to say "off". ---- Without knowing exactly which display you are observing, I can't say exactly what the +1 to -1 scale means (and it really doesn't matter). Most likely it is an arbitrary scale on a display of the instantaneous voltage vs time graph of the music. "+1" or "-1" would represent the maximum value before distortion begins. !! How could "-1" be a maximum? !! Sound is movement of air. Think of the vibrating membrane on a drum. As it bulges out a small increase (relative to ambient pressure) in pressure occurs. For the sake of this discussion we will assign "+" values to an outward bulge. As it bulges in, there is a small decrease in pressure. We will assign these "-" values. These pressure changes travel to your ear and cause your eardrum to move and, after some processing in your brain, you perceive the sound. The out and in bulges tend to be symmetric and we could assign "+1" and "-1" to represent the maximum in and out excursion possible before the membrane suffers terminal trauma. Your sound editing program displays the analog version of the signal so that you can identify exactly when a particular sound ends. Editing is usually more pleasant if the cuts occur at silent instants -- the zero crossings between musical notes. --- Assigning dB values to that -1 point on you computer program's graph is problematic. We don't need to dig into this particular problem, but there is another math issue that you are probably familiar with. 2*2 is two squared. The square root of four is two. The "square root" process finds a number that when squared (multiplying the number by itself), results in the square. Calculating the square root of minus four is a problem. Although a bit more obscure, there is a problem expressing the negative values on your scale in a dB context -- and there is no need to. My point is that your +1 to -1 display does not easily map to anything dB. --- 16 bits implies 65536 different values. If we define our "0dB" reference as the loudest sound that can be stored on the CD format, then the quietest sound could be represented as -96dB. Certainly, there could be quieter sounds in the studio, they just can't be represented on a CD. (Many processes have little problems like this. For example, the dollar currency system has no mechanism to represent fractional cents.) Other than possibly getting some credit on a trick question on an exam, there is no benefit to doing this, but you could replace "+1" on your display with "0dB", "-1" with "0dB" and "0" with "-96db". This is not a good idea, but I though it might help you understand the concepts better. In my college career, if faced with such an exam question, I probably would not have answered this question correctly, and it would have upset me so much that I may not have been able to concentrate on the remainder of the test. Later, I would have tracked down and had words with the person who fabricated the question because it offends one's sense of good practice. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
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#36
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CD Level Variations
In , on 03/16/04
at 11:19 PM, "Bubba" said: [ ... ] While we are at the subject of dbs in CD, I have a dumb question. I understand that Cd range is 96 db with 16 bit depth and each bit represents 6 db. When I see a wav file from a CD on a wave editor such as Goldwave, I see a wave with postive and negative y axis values ( 1 to -1) with 0 being silence. How does it 96 db range map here. What confuses me is that people call 0 db as the full range and other valeus being -20db and so on; how do these amplitude map to wav I see. There are several concepts mixed together above. dB is a relative scale. "0" is the reference. For example, if I ask you, "how high is that picture?", when we are standing in your bedroom, you might say, "8 feet". In this situation the "0" foot reference is implied to be the floor we are standing on, however, we could be standing on the 10th floor of a building that is 2000 feet above sea level. (and, of course, we are at a certain distance from our sun and other celestial bodies.) Without some sort of implied or stated reference and some units of measure, the "8" is a meaningless number. (In other countries "8" could mean 8 meters -- a rather elegant bedroom) There is a tendancy in the audio industry for us to be somewhat sloppy with our dB's. We neglect to state our reference and the units of our measure. We are just lazy. Many times we are working within some sort of context and the reference and units are implied by the conventions of the situation. The real experts are always careful to state their reference and units. The half experts just sling a dB at you, and you must nod and smile to make them, and anyone else in the room, think that you understood their half sense. --- It is customary to peg "0" at the usual (in some context) maximum value. Without getting into some math that you probably have been ducking since highschool, I can't easily explain why, but A dB value that is negative implies a value that is less than the reference. A dB reference above zero implies greater (louder, in an audio context) than the reference. Exactly what happens when a signal goes above zero depends on the context. For example, if "0" is defined as "as loud as you can play your stereo before the neighbors can hear it", then +10 could result in a phone call, the police, or "Vito" banging on your door. If you go to +10 on a tape recorder, you will probably experience some distortion, but there will be no physical damage. This is why -90 on a dB calibrated volume knob is rather quiet and zero is rather loud. Sometimes you'll see minus infinity just below -90. This is another way to say "off". ---- Without knowing exactly which display you are observing, I can't say exactly what the +1 to -1 scale means (and it really doesn't matter). Most likely it is an arbitrary scale on a display of the instantaneous voltage vs time graph of the music. "+1" or "-1" would represent the maximum value before distortion begins. !! How could "-1" be a maximum? !! Sound is movement of air. Think of the vibrating membrane on a drum. As it bulges out a small increase (relative to ambient pressure) in pressure occurs. For the sake of this discussion we will assign "+" values to an outward bulge. As it bulges in, there is a small decrease in pressure. We will assign these "-" values. These pressure changes travel to your ear and cause your eardrum to move and, after some processing in your brain, you perceive the sound. The out and in bulges tend to be symmetric and we could assign "+1" and "-1" to represent the maximum in and out excursion possible before the membrane suffers terminal trauma. Your sound editing program displays the analog version of the signal so that you can identify exactly when a particular sound ends. Editing is usually more pleasant if the cuts occur at silent instants -- the zero crossings between musical notes. --- Assigning dB values to that -1 point on you computer program's graph is problematic. We don't need to dig into this particular problem, but there is another math issue that you are probably familiar with. 2*2 is two squared. The square root of four is two. The "square root" process finds a number that when squared (multiplying the number by itself), results in the square. Calculating the square root of minus four is a problem. Although a bit more obscure, there is a problem expressing the negative values on your scale in a dB context -- and there is no need to. My point is that your +1 to -1 display does not easily map to anything dB. --- 16 bits implies 65536 different values. If we define our "0dB" reference as the loudest sound that can be stored on the CD format, then the quietest sound could be represented as -96dB. Certainly, there could be quieter sounds in the studio, they just can't be represented on a CD. (Many processes have little problems like this. For example, the dollar currency system has no mechanism to represent fractional cents.) Other than possibly getting some credit on a trick question on an exam, there is no benefit to doing this, but you could replace "+1" on your display with "0dB", "-1" with "0dB" and "0" with "-96db". This is not a good idea, but I though it might help you understand the concepts better. In my college career, if faced with such an exam question, I probably would not have answered this question correctly, and it would have upset me so much that I may not have been able to concentrate on the remainder of the test. Later, I would have tracked down and had words with the person who fabricated the question because it offends one's sense of good practice. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
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#37
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CD Level Variations
In , on 03/16/04
at 11:19 PM, "Bubba" said: [ ... ] While we are at the subject of dbs in CD, I have a dumb question. I understand that Cd range is 96 db with 16 bit depth and each bit represents 6 db. When I see a wav file from a CD on a wave editor such as Goldwave, I see a wave with postive and negative y axis values ( 1 to -1) with 0 being silence. How does it 96 db range map here. What confuses me is that people call 0 db as the full range and other valeus being -20db and so on; how do these amplitude map to wav I see. There are several concepts mixed together above. dB is a relative scale. "0" is the reference. For example, if I ask you, "how high is that picture?", when we are standing in your bedroom, you might say, "8 feet". In this situation the "0" foot reference is implied to be the floor we are standing on, however, we could be standing on the 10th floor of a building that is 2000 feet above sea level. (and, of course, we are at a certain distance from our sun and other celestial bodies.) Without some sort of implied or stated reference and some units of measure, the "8" is a meaningless number. (In other countries "8" could mean 8 meters -- a rather elegant bedroom) There is a tendancy in the audio industry for us to be somewhat sloppy with our dB's. We neglect to state our reference and the units of our measure. We are just lazy. Many times we are working within some sort of context and the reference and units are implied by the conventions of the situation. The real experts are always careful to state their reference and units. The half experts just sling a dB at you, and you must nod and smile to make them, and anyone else in the room, think that you understood their half sense. --- It is customary to peg "0" at the usual (in some context) maximum value. Without getting into some math that you probably have been ducking since highschool, I can't easily explain why, but A dB value that is negative implies a value that is less than the reference. A dB reference above zero implies greater (louder, in an audio context) than the reference. Exactly what happens when a signal goes above zero depends on the context. For example, if "0" is defined as "as loud as you can play your stereo before the neighbors can hear it", then +10 could result in a phone call, the police, or "Vito" banging on your door. If you go to +10 on a tape recorder, you will probably experience some distortion, but there will be no physical damage. This is why -90 on a dB calibrated volume knob is rather quiet and zero is rather loud. Sometimes you'll see minus infinity just below -90. This is another way to say "off". ---- Without knowing exactly which display you are observing, I can't say exactly what the +1 to -1 scale means (and it really doesn't matter). Most likely it is an arbitrary scale on a display of the instantaneous voltage vs time graph of the music. "+1" or "-1" would represent the maximum value before distortion begins. !! How could "-1" be a maximum? !! Sound is movement of air. Think of the vibrating membrane on a drum. As it bulges out a small increase (relative to ambient pressure) in pressure occurs. For the sake of this discussion we will assign "+" values to an outward bulge. As it bulges in, there is a small decrease in pressure. We will assign these "-" values. These pressure changes travel to your ear and cause your eardrum to move and, after some processing in your brain, you perceive the sound. The out and in bulges tend to be symmetric and we could assign "+1" and "-1" to represent the maximum in and out excursion possible before the membrane suffers terminal trauma. Your sound editing program displays the analog version of the signal so that you can identify exactly when a particular sound ends. Editing is usually more pleasant if the cuts occur at silent instants -- the zero crossings between musical notes. --- Assigning dB values to that -1 point on you computer program's graph is problematic. We don't need to dig into this particular problem, but there is another math issue that you are probably familiar with. 2*2 is two squared. The square root of four is two. The "square root" process finds a number that when squared (multiplying the number by itself), results in the square. Calculating the square root of minus four is a problem. Although a bit more obscure, there is a problem expressing the negative values on your scale in a dB context -- and there is no need to. My point is that your +1 to -1 display does not easily map to anything dB. --- 16 bits implies 65536 different values. If we define our "0dB" reference as the loudest sound that can be stored on the CD format, then the quietest sound could be represented as -96dB. Certainly, there could be quieter sounds in the studio, they just can't be represented on a CD. (Many processes have little problems like this. For example, the dollar currency system has no mechanism to represent fractional cents.) Other than possibly getting some credit on a trick question on an exam, there is no benefit to doing this, but you could replace "+1" on your display with "0dB", "-1" with "0dB" and "0" with "-96db". This is not a good idea, but I though it might help you understand the concepts better. In my college career, if faced with such an exam question, I probably would not have answered this question correctly, and it would have upset me so much that I may not have been able to concentrate on the remainder of the test. Later, I would have tracked down and had words with the person who fabricated the question because it offends one's sense of good practice. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
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#38
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CD Level Variations
Dave Platt wrote:
I'm sure many of you have experienced the frustration in different playback levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. The compression is often so great that there are two very negative side effects: - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. see, for example, the march of progress on display he http://forums.lukpac.org/viewtopic.php?t=643 -- -S. "They've got God on their side. All we've got is science and reason." -- Dawn Hulsey, Talent Director |
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#39
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CD Level Variations
Dave Platt wrote:
I'm sure many of you have experienced the frustration in different playback levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. The compression is often so great that there are two very negative side effects: - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. see, for example, the march of progress on display he http://forums.lukpac.org/viewtopic.php?t=643 -- -S. "They've got God on their side. All we've got is science and reason." -- Dawn Hulsey, Talent Director |
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#40
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CD Level Variations
Dave Platt wrote:
I'm sure many of you have experienced the frustration in different playback levels when playing CDs in a CD carousel or a CD jukebox, especially in shuffle or random mode. The reason for this may be "technological advances" as most of the seemingly "low- level" CDs are early issues. Anyway, large differences in levels tend to make variations in music programming less than optimum. In my experience, the "technological advances" you cite are precisely backwards. Most modern CDs (popular music in particular) are being mixed/mastered at a very high level, with a very great deal of compression being applied to the signal. The goal of this appears to be a deliberate desire to have the music sound "loud" or "punchy" - that is, attention-getting. It's purely market-and-marketing driven. The compression is often so great that there are two very negative side effects: - The music often has very little dynamic range left - the distance between loudest and softest passages is often only a few dB. see, for example, the march of progress on display he http://forums.lukpac.org/viewtopic.php?t=643 -- -S. "They've got God on their side. All we've got is science and reason." -- Dawn Hulsey, Talent Director |
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