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#1
Posted to rec.audio.pro
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CF recording failure
First time for everything, I suppose. Yesterday, I recorded
a chamber music concert. Marantz PMD-671 & Rode NT4. I've used this combo many times with excellent results. The recording yesterday seemed just fine as it was rolling...it wasn't until I got home that I discovered that three of the seven files (one/track, where a track was an item on the program) were reported as corrupted/unreadable on Windows XP. The 671 has a "3rd head" mode that decodes what's recorded as it's recorded, just like a tape deck. Except... it doesn't work at 88.2kHz/24 bits/sample. Google revealed a ton of programs that purport to rescue damaged data. They all seem to let you try for free, but prohibit saving the result unless you buy the program. Several of them gave up on the damaged files. One didn't. In fact, it rescued two of three and they seem fine. $29... I bought it. It reclaimed the third one, but the result is nothing but shrieking noise, except for a 2-second burst of applause at the very end. The other two are fine. I am betting that the data for that one are ok, but that the ..wav file structure is slightly damaged. (Else, why would the applause at the end be ok?) A buddy suggested that I fire up Linux and use low-level commands to poke around. He'd recovered some "priceless" photos this way. Windows ..wav file format is well-documented. I think that surgical use the linux dd command, and some others, just might let me extract the data and rebuild it as a .wav file, so I'm pursuing that. The other approach is to invite the two players to my home to re-record the track. That might be simpler in the long run. So, my questions are these: does NV memory incorporate ECC? And if not, why not? And, what's the majority opinion on the reliability of these memory cards. I'd used this particular Lexar card many times, so I don't know if the error was a problem with the card or with the 671. It was running on batteries, with fairly long mic cable runs, so I suspect that static electricity may have played a part; no grounding to bleed static. It was a very cold, dry day. Before the 671, I used a Sony HD Minidisc for recording, and it worked well. I think I could hook it to the Line Out or Optical out on the 671 (I think they're active during recording) for a backup. I haven't tried that yet, but I sure will! Thanks, Jason |
#2
Posted to rec.audio.pro
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CF recording failure
"jason" wrote in message .. . [snip] So, my questions are these: does NV memory incorporate ECC? And if not, why not? And, what's the majority opinion on the reliability of these memory cards. I'd used this particular Lexar card many times, so I don't know if the error was a problem with the card or with the 671. It was running on batteries, with fairly long mic cable runs, so I suspect that static electricity may have played a part; no grounding to bleed static. It was a very cold, dry day. There are actually two types of flash: 1. NOR flash, which is made in very small capacities, and has individually addressable cells. The cells are considered reliable, and there is no ECC. 2. NAND flash, used by all flash drives, cards, etc. The cells are unreliable; it's part of the manufacturing process that they do not write reliably, and it's all compensated for by writing the data in ECC, error-correcting-code. NAND is only block-addressable, which gives the ECC a nice long word length. The combination is very reliable, on paper. Yet we all know flash drives fail. SD cards are particularly vulnerable, because they rely on the external equivalent of a disk controller. But your machine uses CF cards, which do contain integral controllers. If a CF card fails, it's entirely the fault of the CF card. There are two types of NAND flash cells: single layer, and multi-layer. The multi-layer cells store three bits per cell, but have a short lifetime. If you have a multilayer CF card, you could have worn it out. This would be unlikely with a single-layer card. Before the 671, I used a Sony HD Minidisc for recording, and it worked well. I think I could hook it to the Line Out or Optical out on the 671 (I think they're active during recording) for a backup. I haven't tried that yet, but I sure will! Thanks, Jason It's always good to have a backup. Bob Morein (310) 237-6511 |
#3
Posted to rec.audio.pro
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CF recording failure
"jason" wrote in message .. . First time for everything, I suppose. Yesterday, I recorded a chamber music concert. Marantz PMD-671 disappointing to hear that I record confrences for pay using a 671 but I do not record above 16 bit 44.1 and i always back my recording up with a minidisc I reformat the cards prior to every recording but I do not like the monitor feature when I move my headphone from the 671 to the mixer if I forget to turn the volume down a distracting bit of delayed audio is heard in the "VERY" quiet room george |
#4
Posted to rec.audio.pro
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CF recording failure
"Soundhaspriority" wrote in message ... "jason" wrote in message .. . [snip] So, my questions are these: does NV memory incorporate ECC? And if not, why not? And, what's the majority opinion on the reliability of these memory cards. I'd used this particular Lexar card many times, so I don't know if the error was a problem with the card or with the 671. It was running on batteries, with fairly long mic cable runs, so I suspect that static electricity may have played a part; no grounding to bleed static. It was a very cold, dry day. There are actually two types of flash: 1. NOR flash, which is made in very small capacities, and has individually addressable cells. The cells are considered reliable, and there is no ECC. 2. NAND flash, used by all flash drives, cards, etc. The cells are unreliable; it's part of the manufacturing process that they do not write reliably, and it's all compensated for by writing the data in ECC, error-correcting-code. NAND is only block-addressable, which gives the ECC a nice long word length. The combination is very reliable, on paper. Yet we all know flash drives fail. SD cards are particularly vulnerable, because they rely on the external equivalent of a disk controller. But your machine uses CF cards, which do contain integral controllers. If a CF card fails, it's entirely the fault of the CF card. There are two types of NAND flash cells: single layer, and multi-layer. The multi-layer cells store three bits per cell, but have a short lifetime. If you have a multilayer CF card, you could have worn it out. This would be unlikely with a single-layer card. Before the 671, I used a Sony HD Minidisc for recording, and it worked well. I think I could hook it to the Line Out or Optical out on the 671 (I think they're active during recording) for a backup. I haven't tried that yet, but I sure will! Thanks, Jason It's always good to have a backup. Bob Morein (310) 237-6511 I recently bought a M Audio Microtrack 2 and 2 x 8GB Kingston CF cards, as I need to make 8 hour uninterrpted recordings. I have been sent 2 replacement machines, the last one has just been sent back for a refund, I've had enough now, as I couldn't get any of the three with either card to reliably complete the recordings - they would randomly hang and the card would be empty on re-boot. Also, the first machines recording time elapsed display was about 10% slow (!!!???), the second machine refused to boot up with one of the cards, the second machine refused to boot with either of the cards, though both cards have made numerous transfers of these large WAV's via a USB reader and my laptop and desktop with no reported errors at all so far. I hadn't realised CF cards are not considered reliable or I would never have gone down this route in the first place. I don't know where the fault lies here, the machines, the cards, or some incompatability/bugs. I'm not impressed. Gareth. |
#5
Posted to rec.audio.pro
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CF recording failure
On Tue, 03 Feb 2009 04:31:01 +0000, jason wrote:
First time for everything, I suppose. Yesterday, I recorded a chamber music concert. Marantz PMD-671 & Rode NT4. I've used this combo many times with excellent results. The recording yesterday seemed just fine as it was rolling...it wasn't until I got home that I discovered that three of the seven files (one/track, where a track was an item on the program) were reported as corrupted/unreadable on Windows XP. The 671 has a "3rd head" mode that decodes what's recorded as it's recorded, just like a tape deck. Except... it doesn't work at 88.2kHz/24 bits/sample. Google revealed a ton of programs that purport to rescue damaged data. They all seem to let you try for free, but prohibit saving the result unless you buy the program. Several of them gave up on the damaged files. One didn't. In fact, it rescued two of three and they seem fine. $29... I bought it. It reclaimed the third one, but the result is nothing but shrieking noise, except for a 2-second burst of applause at the very end. The other two are fine. Sometimes this can be an 'off by one' problem. It might be reading the 16 lower bits of one sample, and the 8 higher bits of the next one as a single 24bit sample. Sounds like horrible noise. Another missing byte near the end may have put it back in sync. I am betting that the data for that one are ok, but that the .wav file structure is slightly damaged. (Else, why would the applause at the end be ok?) A buddy suggested that I fire up Linux and use low-level commands to poke around. He'd recovered some "priceless" photos this way. Windows .wav file format is well-documented. I think that surgical use the linux dd command, and some others, just might let me extract the data and rebuild it as a .wav file, so I'm pursuing that. The other approach is to invite the two players to my home to re-record the track. That might be simpler in the long run. I've done similar things with dd for recovering bad cds. You have to use the flags 'notrunc' (do not truncate after errors), 'noerror' (ignore errors) and sync (so the blocks are padded with nulls to the right size if data is missing, could fix the 'shrieking noise'). I can't remember the exact invocation I used. Rerecording is probably more fun. So, my questions are these: does NV memory incorporate ECC? And if not, why not? And, what's the majority opinion on the reliability of these memory cards. I'd used this particular Lexar card many times, so I don't know if the error was a problem with the card or with the 671. It was running on batteries, with fairly long mic cable runs, so I suspect that static electricity may have played a part; no grounding to bleed static. It was a very cold, dry day. Before the 671, I used a Sony HD Minidisc for recording, and it worked well. I think I could hook it to the Line Out or Optical out on the 671 (I think they're active during recording) for a backup. I haven't tried that yet, but I sure will! Thanks, Jason |
#6
Posted to rec.audio.pro
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CF recording failure
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#7
Posted to rec.audio.pro
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CF recording failure
Gareth Magennis wrote:
I hadn't realised CF cards are not considered reliable or I would never have gone down this route in the first place. I don't know where the fault lies here, the machines, the cards, or some incompatability/bugs. I'm not impressed. So far I have not seen any recording system that I am willing to run without a backup, save for the Nagra. I have seen some big CF issues but no worse than what I have seen with DAT. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#8
Posted to rec.audio.pro
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CF recording failure
"Soundhaspriority" wrote in message ... "Gareth Magennis" wrote in message ... "Soundhaspriority" wrote in message ... "jason" wrote in message .. . [snip] So, my questions are these: does NV memory incorporate ECC? And if not, why not? And, what's the majority opinion on the reliability of these memory cards. I'd used this particular Lexar card many times, so I don't know if the error was a problem with the card or with the 671. It was running on batteries, with fairly long mic cable runs, so I suspect that static electricity may have played a part; no grounding to bleed static. It was a very cold, dry day. There are actually two types of flash: 1. NOR flash, which is made in very small capacities, and has individually addressable cells. The cells are considered reliable, and there is no ECC. 2. NAND flash, used by all flash drives, cards, etc. The cells are unreliable; it's part of the manufacturing process that they do not write reliably, and it's all compensated for by writing the data in ECC, error-correcting-code. NAND is only block-addressable, which gives the ECC a nice long word length. The combination is very reliable, on paper. Yet we all know flash drives fail. SD cards are particularly vulnerable, because they rely on the external equivalent of a disk controller. But your machine uses CF cards, which do contain integral controllers. If a CF card fails, it's entirely the fault of the CF card. There are two types of NAND flash cells: single layer, and multi-layer. The multi-layer cells store three bits per cell, but have a short lifetime. If you have a multilayer CF card, you could have worn it out. This would be unlikely with a single-layer card. Before the 671, I used a Sony HD Minidisc for recording, and it worked well. I think I could hook it to the Line Out or Optical out on the 671 (I think they're active during recording) for a backup. I haven't tried that yet, but I sure will! Thanks, Jason It's always good to have a backup. Bob Morein (310) 237-6511 I recently bought a M Audio Microtrack 2 and 2 x 8GB Kingston CF cards, as I need to make 8 hour uninterrpted recordings. I have been sent 2 replacement machines, the last one has just been sent back for a refund, I've had enough now, as I couldn't get any of the three with either card to reliably complete the recordings - they would randomly hang and the card would be empty on re-boot. Also, the first machines recording time elapsed display was about 10% slow (!!!???), the second machine refused to boot up with one of the cards, the second machine refused to boot with either of the cards, though both cards have made numerous transfers of these large WAV's via a USB reader and my laptop and desktop with no reported errors at all so far. I hadn't realised CF cards are not considered reliable or I would never have gone down this route in the first place. I don't know where the fault lies here, the machines, the cards, or some incompatability/bugs. I'm not impressed. Gareth. Gareth, I didn't mean to imply that CF cards are unreliable. The scheme of unreliable cells combined with massive error correction combines to produce a reliable media (on paper.) People in the r.a.m.p.s. forum use these cards extensively. There are failures, and my personal impression is that the user experience with flash is not as good as with hard disk. However, in the case of low priced flash recorders, I would suspect a design flaw in the recorders. A flash card requires steady power at a good amperage to write. It would be easy to be critical of the Microtrak after a look at the plastic case, and how it's put together on the inside. But that isn't the answer either. It is probably a case of the notorious Chinese quality control. One production run will be good, the next, bad. Many well reviewed products end up causing user misery that is not reflected in the reviews, because the quality control slipped after the first run. I wish I had an easy solution for you. It will probably take a lot of persistence by you with M-Audio to get them to make good. Bob Morein (310) 237-6511 I've given up on the Microtrack, no point getting any more from the same batch. Pity, because for the price and features it is very good, and one of the very few that will record more that 2GB without stopping. As it turns out, my Laptop (oldish Sony Vaio, Tascam USB interface, XP, Audition) has been faultless - the Microtrack was bought because I didn't consider a laptop to be reliable enough. Cheers, Gareth. |
#9
Posted to rec.audio.pro
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CF recording failure
On Tue, 03 Feb 2009 16:31:19 +0000, jason wrote:
snip I buddy has used low-level Linux commands to rescue "priceless" digital photos from CF cards. I have Linux installed, but it hadn't occured to me to try it. .wav files have a well-documented format, so if I can suck off all the data with the byte-level dd copy command, and assuming that the data were recorded sequentially (a good bet, since the card had just been formatted), I may be able to effect a rescue. Then again, it may be simpler to invite the two performers to my home to re-record the track... Try making an image of the drive with dd (with padding/error ignore etc) and mount the image as a loopback device. If enough of the filesystem remains intact you should be able to copy the files as normal from the image with valid headers, though they will have small missing sections. This is easier than hunting through the bytes with a hex editor. You can also try other filesystem recovery operations on the image without risking the original data. |
#10
Posted to rec.audio.pro,aus.hi-fi,rec.arts.movies.production.sound
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CF recording failure
"Gareth Magennis" wrote in message ... "Soundhaspriority" wrote in message ... "jason" wrote in message .. . [snip] So, my questions are these: does NV memory incorporate ECC? And if not, why not? And, what's the majority opinion on the reliability of these memory cards. I'd used this particular Lexar card many times, so I don't know if the error was a problem with the card or with the 671. It was running on batteries, with fairly long mic cable runs, so I suspect that static electricity may have played a part; no grounding to bleed static. It was a very cold, dry day. There are actually two types of flash: 1. NOR flash, which is made in very small capacities, and has individually addressable cells. The cells are considered reliable, and there is no ECC. 2. NAND flash, used by all flash drives, cards, etc. The cells are unreliable; it's part of the manufacturing process that they do not write reliably, and it's all compensated for by writing the data in ECC, error-correcting-code. NAND is only block-addressable, which gives the ECC a nice long word length. The combination is very reliable, on paper. Yet we all know flash drives fail. SD cards are particularly vulnerable, because they rely on the external equivalent of a disk controller. But your machine uses CF cards, which do contain integral controllers. If a CF card fails, it's entirely the fault of the CF card. There are two types of NAND flash cells: single layer, and multi-layer. The multi-layer cells store three bits per cell, but have a short lifetime. If you have a multilayer CF card, you could have worn it out. This would be unlikely with a single-layer card. Before the 671, I used a Sony HD Minidisc for recording, and it worked well. I think I could hook it to the Line Out or Optical out on the 671 (I think they're active during recording) for a backup. I haven't tried that yet, but I sure will! Thanks, Jason It's always good to have a backup. Bob Morein (310) 237-6511 I recently bought a M Audio Microtrack 2 and 2 x 8GB Kingston CF cards, as I need to make 8 hour uninterrpted recordings. I have been sent 2 replacement machines, the last one has just been sent back for a refund, I've had enough now, as I couldn't get any of the three with either card to reliably complete the recordings - they would randomly hang and the card would be empty on re-boot. Also, the first machines recording time elapsed display was about 10% slow (!!!???), the second machine refused to boot up with one of the cards, the second machine refused to boot with either of the cards, though both cards have made numerous transfers of these large WAV's via a USB reader and my laptop and desktop with no reported errors at all so far. I hadn't realised CF cards are not considered reliable or I would never have gone down this route in the first place. I don't know where the fault lies here, the machines, the cards, or some incompatability/bugs. I'm not impressed. Gareth. Gareth, I didn't mean to imply that CF cards are unreliable. The scheme of unreliable cells combined with massive error correction combines to produce a reliable media (on paper.) People in the r.a.m.p.s. forum use these cards extensively. There are failures, and my personal impression is that the user experience with flash is not as good as with hard disk. However, in the case of low priced flash recorders, I would suspect a design flaw in the recorders. A flash card requires steady power at a good amperage to write. It would be easy to be critical of the Microtrak after a look at the plastic case, and how it's put together on the inside. But that isn't the answer either. It is probably a case of the notorious Chinese quality control. One production run will be good, the next, bad. Many well reviewed products end up causing user misery that is not reflected in the reviews, because the quality control slipped after the first run. I wish I had an easy solution for you. It will probably take a lot of persistence by you with M-Audio to get them to make good. If you need some help harassing them, I am very experienced at intimidating weak people to do my bidding. Bob Morein (310) 237-6511 |
#11
Posted to rec.audio.pro
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CF recording failure
"jason" wrote in message
So, my questions are these: does NV memory incorporate ECC? I doubt it. As a rule, consumer RAM does not use ECC. Hard drives do. And if not, why not? The cost of the extra bits and circuitry to manage it does not seem to have a reasonable return for almost all single-user applications and even when there is workgroup-level sharing. ECC is primarly used in high end servers where 100's or 1,000s of users are impacted by random failures. How long does your PC run between *having* to be booted? I have some that only get booted for major hardware or software changes, physical moves and power failures. And, what's the majority opinion on the reliability of these memory cards. There are a jillion brands of flash cards. They use a small number of sources for flash chips and interface chips, but there is still probably plenty of mixing and matching. I've never had one do anything but either work or totally fail. That includes trips through pretty heavily chlorinated water in our municipal swimming pool. That one worked after a reasonable drying cycle in my food dehydrator. I'd used this particular Lexar card many times, so I don't know if the error was a problem with the card or with the 671. I find this story interesting. I have a Microtrack, and it has been flawless. One of my associates never could be comfortable with his Microtrack, and eventually got a Marantz flash-based recorder. AFAIK his has also been flawless. It was running on batteries, with fairly long mic cable runs, so I suspect that static electricity may have played a part; no grounding to bleed static. It was a very cold, dry day. Good equipment should tolerate all that, no sweat. But back in the real world - live and learn! |
#12
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CF recording failure
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#13
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CF recording failure
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#14
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CF recording failure
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#15
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CF recording failure
"jason" wrote in message .. . In article , says... I doubt it. As a rule, consumer RAM does not use ECC. Hard drives do. I learned here that CF cards, unlike some other flash memory packages (SD cards) incorporate their own DMA controller and do incorporate ECC. I was wrong about ECC not being used: http://en.wikipedia.org/wiki/Flash_memory "NAND (flash memory) relies on ECC to compensate for bits that may spontaneously fail during normal device operation. This ECC may correct as little as one bit error in each 2048 bits, or up to 22 bits in each 2048 bits.[7] If ECC cannot correct the error during read, it may still detect the error. When doing erase or program operations, the device can detect blocks that fail to program or erase and mark them bad. The data is then written to a different, good block, and the bad block map is updated. "Most NAND devices are shipped from the factory with some bad blocks which are typically identified and marked according to a specified bad block marking strategy. By allowing some bad blocks, the manufacturers achieve far higher yields than would be possible if all blocks had to be verified good. This significantly reduces NAND flash costs and only slightly decreases the storage capacity of the parts. Apparently NOR Flash is more relaible. |
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