CD Audio Error Correction on PC -- WTF?

[Karl Uppiano[_2_]]

For the last 20+ years, I have nearly always listened to CDs on high quality
dedicated CD players, only occasionally listening casually through my PC.
Recently though, I received an iPod as a gift, and since I now have enough
hard drive space to store my entire CD collection in lossless format, I
started ripping CDs to my hard drive. So far, so good.

Then, I discovered that some of my CDs that sound fine on my dedicated CD
player sound obviously defective from the ripped copy. I also discovered
that iTunes and Windows Media player have CD error correction turned off by
default! They just do scatter-gather reads, feed forward from the CD, and
*assume* that the data is correct. But wait, it gets worse: When I enable
error correction, in addition to sounding distorted and raspy, now it's
scrambled too. Blocks are being stored out of order. The iTunes error
correction algorithm is obviously not adequate, or even appropriate!

There is high-quality ripping software out there, such as EAC (Exact Audio
Copy), which I haven't tried yet. But reading their web site, I gather that
EAC can only infer whether errors exist; it does not have access to the
low-level CD data for proper red book error detection, correction and
concealment. It can only read, and re-read the same buffer until it gets
some agreement. Some (not all) CD-ROM drives will indicate if an error
occurred, and EAC can get a clue from that, but the whole process is
hopelessly slow. I hope I am mistaken but my research so far indicates that
PCs simply cannot play or rip CD Audio with real-time error detection,
correction and concealment through the SCSI/ATAPI digital interface.

Given the fact that the majority of consumers now listen to CDs (directly or
indirectly) through their PCs, why don't CD-ROM drives provide a CD audio
streaming mode that outputs the same multi-level error detection, correction
and concealment that dedicated CD players send to their D/A converters? Does
anybody know the answer to this? Are there CD-ROM/DVD/Blu-ray drives that
can do this?

[Dave Platt]

In article >,
Karl Uppiano > wrote:

>Given the fact that the majority of consumers now listen to CDs (directly or
>indirectly) through their PCs, why don't CD-ROM drives provide a CD audio
>streaming mode that outputs the same multi-level error detection, correction
>and concealment that dedicated CD players send to their D/A converters? Does
>anybody know the answer to this? Are there CD-ROM/DVD/Blu-ray drives that
>can do this?

Someone (I wish I know who) said something wise a few years ago.
Roughly put, "If the question is `why don't they?', the answer usually
works out to be some form of the word `money'."

Based on what I've seen, CD-ROM drives (at least the ones I have
tested) do generally apply the same C1/C2 Reed-Solomon error detection
and correction logic to the data that they provide to the IDE (or
SCSI) interface, as they do to the data going out the DACs. The C1/C2
error correction logic is pretty much hard-wired into the silicon in
the drives' controllers.

The problems occur if the data (which is chock-full of low-level
errors) cannot be corrected by the C1/C2 logic. During audio
playback, a "bad sample" signal from the C1/C2 corrector will cause
the DAC to either duplicate the previous sample, interpolate between
the two valid samples on either side of the error, or (in the case of
multiple bad samples) briefly mute the output. This "error
concealment" process is usually not audible to the ear.

Unfortunately, many CD-ROM drives don't perform error concealment on
the audio samples being fed over the ATAPI (or SCSI) bus. Bad samples
get through, unconcealed, and with no warning to the PC.

Other drives do proper error concealment on this data, and I believe
that some will even try re-reading the data block one or more times in
order to recover good data before sending it to the PC. Plextor SCSI
drives had (and perhaps still have?) an excellent reputation for
reading audio CDs accurately, even at high speed.

I believe I've seen one or two types of drive which did error
concealment well when they were reading audio CD data at low speeds,
but failed to do the concealment at high speeds.

I suspect that the lack of good error concealment on the data bus
comes back to money again... it might require using a faster (more
expensive) processor, or slowing down the drive's read speed (and
losing competitive points in the marketing game). In other cases, it
is (or was) due to simple ignorance on the part of the firmware
engineers... they hadn't realized that error concealment of audio data
on the ATAPI bus was a necessary feature. [I ran into this problem
back in the early 1990s when doing a CD-ROM driver for the
first-generation 3DO videogame system, and had some interesting
discussions with the drive firmware engineers during the discussions
which persuaded them to add this feature to the drive.]

--
Dave Platt > AE6EO
Friends of 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!

[Mr.T]

"Karl Uppiano" > wrote in message
...
> For the last 20+ years, I have nearly always listened to CDs on high
quality
> dedicated CD players, only occasionally listening casually through my PC.
> Recently though, I received an iPod as a gift, and since I now have enough
> hard drive space to store my entire CD collection in lossless format, I
> started ripping CDs to my hard drive. So far, so good.
>
> Then, I discovered that some of my CDs that sound fine on my dedicated CD
> player sound obviously defective from the ripped copy. I also discovered
> that iTunes and Windows Media player have CD error correction turned off
by
> default! They just do scatter-gather reads, feed forward from the CD, and
> *assume* that the data is correct. But wait, it gets worse: When I enable
> error correction, in addition to sounding distorted and raspy, now it's
> scrambled too. Blocks are being stored out of order. The iTunes error
> correction algorithm is obviously not adequate, or even appropriate!
>
> There is high-quality ripping software out there, such as EAC (Exact Audio
> Copy), which I haven't tried yet. But reading their web site, I gather
that
> EAC can only infer whether errors exist; it does not have access to the
> low-level CD data for proper red book error detection, correction and
> concealment. It can only read, and re-read the same buffer until it gets
> some agreement. Some (not all) CD-ROM drives will indicate if an error
> occurred, and EAC can get a clue from that, but the whole process is
> hopelessly slow. I hope I am mistaken but my research so far indicates
that
> PCs simply cannot play or rip CD Audio with real-time error detection,
> correction and concealment through the SCSI/ATAPI digital interface.
>
> Given the fact that the majority of consumers now listen to CDs (directly
or
> indirectly) through their PCs, why don't CD-ROM drives provide a CD audio
> streaming mode that outputs the same multi-level error detection,
correction
> and concealment that dedicated CD players send to their D/A converters?
Does
> anybody know the answer to this? Are there CD-ROM/DVD/Blu-ray drives that
> can do this?

You don't want it! Since CD/DVD drives operate much faster than real time,
the drive can re-read data as necessary to provide full error correction.
IF the disk cannot be read without error, EAC *will* in fact let you know.
There are programs that can still recover as much data as possible, and
programs that can interpolate (conceal) any errors if necessary, or you can
edit the wave files yourself. This should hardly ever be necessary if you do
not use your disks as Frisbees!

So the short answer is ripping files with a computer hardly ever requires
concealment, and usually provides MORE accurate data than a standard CD
player can.
I simply fail to see any disadvantage in the computer route when using
*good* software, (EAC is free after all!) and far from being "hopelessly
slow" is always far faster than real time for me. But then I *never* use
iTunes or Windows Media Player.

MrT.

[Karl Uppiano[_2_]]

"Mr.T" <MrT@home> wrote in message
...
>
> "Karl Uppiano" > wrote in message
> ...
>> For the last 20+ years, I have nearly always listened to CDs on high
> quality
>> dedicated CD players, only occasionally listening casually through my PC.
>> Recently though, I received an iPod as a gift, and since I now have
>> enough
>> hard drive space to store my entire CD collection in lossless format, I
>> started ripping CDs to my hard drive. So far, so good.
>>
>> Then, I discovered that some of my CDs that sound fine on my dedicated CD
>> player sound obviously defective from the ripped copy. I also discovered
>> that iTunes and Windows Media player have CD error correction turned off
> by
>> default! They just do scatter-gather reads, feed forward from the CD, and
>> *assume* that the data is correct. But wait, it gets worse: When I enable
>> error correction, in addition to sounding distorted and raspy, now it's
>> scrambled too. Blocks are being stored out of order. The iTunes error
>> correction algorithm is obviously not adequate, or even appropriate!
>>
>> There is high-quality ripping software out there, such as EAC (Exact
>> Audio
>> Copy), which I haven't tried yet. But reading their web site, I gather
> that
>> EAC can only infer whether errors exist; it does not have access to the
>> low-level CD data for proper red book error detection, correction and
>> concealment. It can only read, and re-read the same buffer until it gets
>> some agreement. Some (not all) CD-ROM drives will indicate if an error
>> occurred, and EAC can get a clue from that, but the whole process is
>> hopelessly slow. I hope I am mistaken but my research so far indicates
> that
>> PCs simply cannot play or rip CD Audio with real-time error detection,
>> correction and concealment through the SCSI/ATAPI digital interface.
>>
>> Given the fact that the majority of consumers now listen to CDs (directly
> or
>> indirectly) through their PCs, why don't CD-ROM drives provide a CD audio
>> streaming mode that outputs the same multi-level error detection,
> correction
>> and concealment that dedicated CD players send to their D/A converters?
> Does
>> anybody know the answer to this? Are there CD-ROM/DVD/Blu-ray drives that
>> can do this?
>
> You don't want it! Since CD/DVD drives operate much faster than real time,
> the drive can re-read data as necessary to provide full error correction.
> IF the disk cannot be read without error, EAC *will* in fact let you know.
> There are programs that can still recover as much data as possible, and
> programs that can interpolate (conceal) any errors if necessary, or you
> can
> edit the wave files yourself. This should hardly ever be necessary if you
> do
> not use your disks as Frisbees!

The particular CD in question is in excellent shape, and I have never had
problems with it playing on regular audio players.

> So the short answer is ripping files with a computer hardly ever requires
> concealment, and usually provides MORE accurate data than a standard CD
> player can.
> I simply fail to see any disadvantage in the computer route when using
> *good* software, (EAC is free after all!) and far from being "hopelessly
> slow" is always far faster than real time for me. But then I *never* use
> iTunes or Windows Media Player.

Well, ok. The interesting thing is, the CD sounds fine on a regular audio CD
player, yet I cannot get a decent copy on any PC I've tried so far. Using
EAC, it spent a couple hours on the first two tracks alone. I finally gave
up. Something odd is happening here.

[Mr.T]

"Karl Uppiano" > wrote in message
...
> Well, ok. The interesting thing is, the CD sounds fine on a regular audio
CD
> player, yet I cannot get a decent copy on any PC I've tried so far. Using
> EAC, it spent a couple hours on the first two tracks alone. I finally gave
> up. Something odd is happening here.

Sounds more like a copy protection problem then. Try using the non secure
burst mode, or another ripper.

Mrt.

[Arny Krueger]

"Karl Uppiano" > wrote in message


> There is high-quality ripping software out there, such as
> EAC (Exact Audio Copy), which I haven't tried yet.

Shame on you for not trying EAC before complainging about it. There is a
reason why so many picky people use it. Is the high price holding you off ?
;-)

> But reading their web site, I gather that EAC can only infer
> whether errors exist; it does not have access to the
> low-level CD data for proper red book error detection,
> correction and concealment. It can only read, and re-read
> the same buffer until it gets some agreement. Some (not
> all) CD-ROM drives will indicate if an error occurred,
> and EAC can get a clue from that, but the whole process
> is hopelessly slow.

I think that I generally get rips out of EAC at speeds averaging better than
7 times real time. IOW, it takes 10 minutes or less to rip a 70 minute CD.
Would you call that "hopelessly slow"? ;-)

If I rip a CD I burned from a .wav file, EAC generally recovers exactly that
..wav file, based on bit-for-bit compairson checking. Either that, or returns
an error, message which is very rare. On occasion, I've used EAC to
reconstruct the contents of a CD that was too badly scratched up to play on
any of my CD players. I just burn a new CD, and continue to enjoy the music.

[Geoff]

Karl Uppiano wrote:
..
>
> Well, ok. The interesting thing is, the CD sounds fine on a regular
> audio CD player, yet I cannot get a decent copy on any PC I've tried
> so far. Using EAC, it spent a couple hours on the first two tracks
> alone. I finally gave up. Something odd is happening here.

And oddly I've never experienced the problem you appear to. Maybe your
CD-ROM is faulty ?

Tried a different CD ?.It may look fine but in fact be very poor. Get a
Plextor Premium and you can test exactly how good/poor it is.


geoff

[Karl Uppiano[_2_]]

"Arny Krueger" > wrote in message
...
> "Karl Uppiano" > wrote in message
>
>
>> There is high-quality ripping software out there, such as
>> EAC (Exact Audio Copy), which I haven't tried yet.
>
> Shame on you for not trying EAC before complainging about it. There is a
> reason why so many picky people use it. Is the high price holding you off
> ? ;-)

Please don't think I was complaining about EAC. I read the documentation,
understood the process it has to use, and drew my conclusions from that. EAC
doesn't have direct, real-time access to the C1 and C2 error correction data
from the raw media. So EAC must infer by re-reading and comparing buffers
multiple times (evidently it gets some error info from some drives, so
performance will vary depending on the drive). It isn't EAC's fault; it has
to work with what's available. My complaint was that C1 and C2 correction
and concealment doesn't seem to be available in the digital data via the
SCSI/ATAPI port. If it is available, then I stand corrected, but my research
indicated otherwise. The drive literature doesn't talk about this, and most
drives that OEM with computers probably aren't particularly focused on CD
performance.

C1 and C2 correction and concealment work in real-time, when available (at
whatever rate real-time is when ripping). If they're not available, or if
additional error correction is needed, tools like EAC can be incredibly
useful, but they work by repeatedly reading and comparing the audio buffers
until they get multiple buffers in agreement. That is very time-consuming no
matter how you slice it, and it will always be slower than not using it.

And I did download and try EAC as soon as I had the opportunity. It is nice,
but it took about an hour to get through the first track and a half of the
CD I'm having trouble with. There might be something unusual about this CD,
but I feel that my claim of being hopelessly slow is vindicated. Again, I'm
not blasting EAC, but when it has to read and compare each buffer up to 32
times, that's going to take a while. It isn't an opinion, it's a statement
of fact.

>> But reading their web site, I gather that EAC can only infer
>> whether errors exist; it does not have access to the
>> low-level CD data for proper red book error detection,
>> correction and concealment. It can only read, and re-read
>> the same buffer until it gets some agreement. Some (not
>> all) CD-ROM drives will indicate if an error occurred,
>> and EAC can get a clue from that, but the whole process
>> is hopelessly slow.
>
> I think that I generally get rips out of EAC at speeds averaging better
> than 7 times real time. IOW, it takes 10 minutes or less to rip a 70
> minute CD. Would you call that "hopelessly slow"? ;-)

That is what I would expect when a CD is in good shape, and raw errors are
few.

> If I rip a CD I burned from a .wav file, EAC generally recovers exactly
> that .wav file, based on bit-for-bit compairson checking. Either that, or
> returns an error, message which is very rare. On occasion, I've used EAC
> to reconstruct the contents of a CD that was too badly scratched up to
> play on any of my CD players. I just burn a new CD, and continue to enjoy
> the music.

Again, I think EAC is a fine tool for its intended use, and for a CD that is
an otherwise lost cause, I really don't care how long it might take to fix
it. My original post was about the apparent inability to get C2 and C2
correction out of CD-ROMs, requiring the use of tools like EAC for CDs that
play fine on dedicated audio CD players, but won't rip cleanly without help.

[Mr.T]

"Karl Uppiano" > wrote in message
...
> Please don't think I was complaining about EAC. I read the documentation,
> understood the process it has to use, and drew my conclusions from that.
EAC
> doesn't have direct, real-time access to the C1 and C2 error correction
data
> from the raw media.

Of course it has access to the drive error information, *IF* the particular
drive provides it.

Just why you keep complaining here rather than trying another disk or drive
is beyond me.
So try some other CD's, and if necessary buy a decent drive. They are
certainly cheap enough these days!

>So EAC must infer by re-reading and comparing buffers
> multiple times (evidently it gets some error info from some drives, so
> performance will vary depending on the drive).

Exactly, it will even tell you your drives capability, so if your drive is
crap, buy a new one and stop complaining.


>It isn't EAC's fault; it has to work with what's available.

And does a damn fine job with most modern drives IME.

>My complaint was that C1 and C2 correction
> and concealment doesn't seem to be available in the digital data via the
> SCSI/ATAPI port. If it is available, then I stand corrected,

Stand corrected on the error reporting then, concealment is another matter
altogether, and NOT something I want in my CD/DVD ROM drives!


> C1 and C2 correction and concealment work in real-time, when available (at
> whatever rate real-time is when ripping).

Ripping is not usually done in real time, because nobody would want that!


If they're not available, or if
> additional error correction is needed, tools like EAC can be incredibly
> useful, but they work by repeatedly reading and comparing the audio
buffers
> until they get multiple buffers in agreement.

You say this so many times, but EAC only does it when the drive does not
report errors. Most modern ones do. Get a new drive if necessary!

>That is very time-consuming no
> matter how you slice it, and it will always be slower than not using it.

And yet almost always still faster than real time for all drives and CD's I
have tried (dozens of drives and thousands of disks!)
the only few exceptions are a couple of badly copy protected disks, and a
couple of seriously damaged disks.

> And I did download and try EAC as soon as I had the opportunity. It is
nice,
> but it took about an hour to get through the first track and a half of the
> CD I'm having trouble with.

And with the other CD's you have tried?
Either your drive is poor, or you are simply trying to read a disk that has
been deliberately made faulty in an attempt at copy protection.
(that's my bet) Does the disk cover mention copy protection?


>There might be something unusual about this CD,
> but I feel that my claim of being hopelessly slow is vindicated.

On that disk maybe, when you have tried a few dozen other disks, and perhaps
another drive, get back to us.
Of course I should mention that EAC needs to be set for your drive,
something you may not be capable of, going by what you have posted so far.

>Again, I'm
> not blasting EAC, but when it has to read and compare each buffer up to 32
> times, that's going to take a while. It isn't an opinion, it's a statement
> of fact.

And it's still a *WRONG* statement of fact for the VAST majority of drives
and disks however.
I usually get secure rips at 10-20* real time.
Just how much longer will you complain about one disk before admitting the
problem is not with EAC?

For all your whinging, it would be far easier to just connect your CD player
output to your soundcard input, record in real time, and get on with life,
if you are unable to get anything else to work!
I have only ever needed to do that once in 1,000+ disks however.

MrT.

[Steven Sullivan]

Karl Uppiano > wrote:
> Well, ok. The interesting thing is, the CD sounds fine on a regular audio CD
> player, yet I cannot get a decent copy on any PC I've tried so far. Using
> EAC, it spent a couple hours on the first two tracks alone. I finally gave
> up. Something odd is happening here.

Indeed. Your first post was odd -- in years of ripping
I've never heard a CD that was so badly ripped yet still playable,
that it sounded 'raspy' or whatever. But then again, I've never used
iTunes or WMP to rip CDs. But I've never heard them to be notoriously bad
rippers, and I think I'd have heard about it by now if they were.

EAC or dbPoweramp should do the job nicely, and should take just a few minutes
per CD in secure mode, if everything is set up properly and the disc isn't massively
defective. If the ripper uses Accuraterip (EAC can be set up for it, dbPoweramp has it by
default) then it's even faster, since you can use burst mode.



--
-S
We have it in our power to begin the world over again - Thomas Paine

[Steven Sullivan]

Karl Uppiano > wrote:

> And I did download and try EAC as soon as I had the opportunity. It is nice,
> but it took about an hour to get through the first track and a half of the
> CD I'm having trouble with. There might be something unusual about this CD,
> but I feel that my claim of being hopelessly slow is vindicated.

It's not. Tens of thousands of users have used EAC , in high-secure mode, without
it taking 'hours;' to rip a CD. Typically it's less than 10 minutes. If the
CD is scratched, or has some serious DRM, it could take longer -- and you will see it
churnign through the damaged area -- but in such cases you could always
use Test & Copy with burst mode instead -- if you get the same CRC twice, it's unlikely there
are any errors in the read.


> Again, I think EAC is a fine tool for its intended use, and for a CD that is
> an otherwise lost cause, I really don't care how long it might take to fix
> it. My original post was about the apparent inability to get C2 and C2
> correction out of CD-ROMs, requiring the use of tools like EAC for CDs that
> play fine on dedicated audio CD players, but won't rip cleanly without help.

Again, try comparing CRCs, or try using a ripper with Accuraterip



--
-S
We have it in our power to begin the world over again - Thomas Paine

[Steven Sullivan]

Mr.T <MrT@home> wrote:


> And does a damn fine job with most modern drives IME.


It did a damn fine job with drives from five years ago too...which is around the time
I ripped ~1000 CDs to FLAC.

> Just how much longer will you complain about one disk before admitting the
> problem is not with EAC?

Here's to hoping.




--
-S
We have it in our power to begin the world over again - Thomas Paine

[Dave Platt]

In article >,
Karl Uppiano > wrote:

>Please don't think I was complaining about EAC. I read the documentation,
>understood the process it has to use, and drew my conclusions from that. EAC
>doesn't have direct, real-time access to the C1 and C2 error correction data
>from the raw media. So EAC must infer by re-reading and comparing buffers
>multiple times (evidently it gets some error info from some drives, so
>performance will vary depending on the drive). It isn't EAC's fault; it has
>to work with what's available. My complaint was that C1 and C2 correction
>and concealment doesn't seem to be available in the digital data via the
>SCSI/ATAPI port. If it is available, then I stand corrected, but my research
>indicated otherwise.

I believe you're correct. I've never seen a CD-ROM drive which had
access to the data prior to the C1/C2 corrections.

The C1/C2 correction process is intimately inter-woven with the
process of de-interleaving the data blocks. If you were able to get
the data prior to the C1/C2 correction (i.e. the raw bitstream from
the CD player's photodetector), you would have to implement a complete
Reed-Solomon de-interleaving/correction process in the host.

I suspect that there are probably some very specialized CD drives which
do make this bitstream available, but they're probably limited to
units used to perform evaluation in the CD factories.

The closest thing I'm aware of in the consumer (or even pro-sumer)
space, is the Plextor drives which can give you a count of the number
of C2 errors (correctable and uncorrectable).

>C1 and C2 correction and concealment work in real-time, when available (at
>whatever rate real-time is when ripping).

C1/C2 error correction is always available and always operating.

What you don't get (in a lot of drives) is any concealment (or
notification), if the C2 phase fails and a bad symbol comes out.

>And I did download and try EAC as soon as I had the opportunity. It is nice,
>but it took about an hour to get through the first track and a half of the
>CD I'm having trouble with. There might be something unusual about this CD,
>but I feel that my claim of being hopelessly slow is vindicated. Again, I'm
>not blasting EAC, but when it has to read and compare each buffer up to 32
>times, that's going to take a while. It isn't an opinion, it's a statement
>of fact.

I haven't used EAC, but I've made use of a program called "cdparanoia"
which runs on Linux... same idea, different implementation.

What I've observed with cdparanoia is that many CDs can be ripped
(very accurately) quite quickly... if their low-level bit error rate
is low enough, cdparanoia reads each set of blocks only a few times
(two or three, I believe), confirms that the data matches up, and
moves on. The only time that a paranoid rip takes a long time, is if
the disc's bit error rate is high, and different errors (or different
concealments) are occurring each time a block is re-read.

I suspect that EAC may work in the same way... you might want to try
it with a known-good CD and see how well it behaves.

The fact that you're having trouble ripping this one CD reliably
suggests to me that it's defective in some way, and has an
unusually high bit-error rate which is causing a large amount of
C1/C2 correction failure (and thus error concealment) during playback.

Bad CDs do occur - some are bad when they come off the line, and some
(relatively few, older) suffer from decay problems such as "bronzing"
which causes them to become unplayable after a few years.

--
Dave Platt > AE6EO
Friends of 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!

[Mr.T]

"Steven Sullivan" > wrote in message
...
> Mr.T <MrT@home> wrote:
> > And does a damn fine job with most modern drives IME.
>
> It did a damn fine job with drives from five years ago too...which is
around the time
> I ripped ~1000 CDs to FLAC.

Since my first CDROM drive was a couple of decades ago, a five year old
drive is modern :-)
Some of that vintage do work better than others however. Even now some do a
better job than others of course, hence "most".

MrT.

[Mr.T]

"Dave Platt" > wrote in message
...
> I've never seen a CD-ROM drive which had
> access to the data prior to the C1/C2 corrections.]

The data prior to error *correction* is usually irrelevant. The important
thing is for the drive to report when it CAN'T fully correct the error.

> The closest thing I'm aware of in the consumer (or even pro-sumer)
> space, is the Plextor drives which can give you a count of the number
> of C2 errors (correctable and uncorrectable).

As well as many Lite-On drives when used with suitable software.
And possibly others I am unaware of.

> What I've observed with cdparanoia is that many CDs can be ripped
> (very accurately) quite quickly... if their low-level bit error rate
> is low enough, cdparanoia reads each set of blocks only a few times
> (two or three, I believe), confirms that the data matches up, and
> moves on.

Only once is required if there are no errors, and the drive can tell that.

>The only time that a paranoid rip takes a long time, is if
> the disc's bit error rate is high, and different errors (or different
> concealments) are occurring each time a block is re-read.
>
> I suspect that EAC may work in the same way... you might want to try
> it with a known-good CD and see how well it behaves.

As has already been suggested many times already.

> The fact that you're having trouble ripping this one CD reliably
> suggests to me that it's defective in some way, and has an
> unusually high bit-error rate which is causing a large amount of
> C1/C2 correction failure (and thus error concealment) during playback.
>
> Bad CDs do occur - some are bad when they come off the line, and some
> (relatively few, older) suffer from decay problems such as "bronzing"
> which causes them to become unplayable after a few years.

And as I have already suggested, some are deliberately faulty in an attempt
at copy protection.

MrT.

[Karl Uppiano[_2_]]

"Mr.T" <MrT@home> wrote in message
u...
>
> "Karl Uppiano" > wrote in message
> ...
>> Please don't think I was complaining about EAC. I read the documentation,
>> understood the process it has to use, and drew my conclusions from that.
> EAC
>> doesn't have direct, real-time access to the C1 and C2 error correction
> data
>> from the raw media.
>
> Of course it has access to the drive error information, *IF* the
> particular
> drive provides it.
>
> Just why you keep complaining here rather than trying another disk or
> drive
> is beyond me.
> So try some other CD's, and if necessary buy a decent drive. They are
> certainly cheap enough these days!

I'm not sure what the point is with all the hostility. You write as if I've
been complaining about this for weeks in recurring threads. I brought it up
a day or two ago, and responded to some people. That's it. It seems that the
disc must be "denatured" somehow, and that's it. What I still has not been
answered to my satisfaction is if CD audio gets the same treatment --
correction and concealment -- in CDROM drives that they do in audio drives.
I suspect that they do not, because the CD sounds fine in audio drives, but
not in the few CDROM drives that I checked.

>>So EAC must infer by re-reading and comparing buffers
>> multiple times (evidently it gets some error info from some drives, so
>> performance will vary depending on the drive).
>
> Exactly, it will even tell you your drives capability, so if your drive is
> crap, buy a new one and stop complaining.

I checked it in several other drives; I just didn't have a chance to respond
about that in all the discussion that you read (not in real time). Stop
assuming I'm stupid or unwilling to change just because I haven't answered
everyone's questions in your particular reading order!

>>It isn't EAC's fault; it has to work with what's available.
>
> And does a damn fine job with most modern drives IME.
>
>>My complaint was that C1 and C2 correction
>> and concealment doesn't seem to be available in the digital data via the
>> SCSI/ATAPI port. If it is available, then I stand corrected,
>
> Stand corrected on the error reporting then, concealment is another matter
> altogether, and NOT something I want in my CD/DVD ROM drives!

Correction and concealment according to the redbook spec is what I'm talking
about. That hasn't been answered, and if you don't want concealment, then
fine, but I think it should be an available option.

>> C1 and C2 correction and concealment work in real-time, when available
>> (at
>> whatever rate real-time is when ripping).
>
> Ripping is not usually done in real time, because nobody would want that!

You missed my point. I said C1 and C2 correction can be done "at whatever
rate real-time is when ripping". If that is 8x or whatever, then C1 and C2
correction can be done at that rate. It is a low overhead process, and works
remarkably well.

> If they're not available, or if
>> additional error correction is needed, tools like EAC can be incredibly
>> useful, but they work by repeatedly reading and comparing the audio
> buffers
>> until they get multiple buffers in agreement.
>
> You say this so many times, but EAC only does it when the drive does not
> report errors. Most modern ones do. Get a new drive if necessary!

This bitch has already been addressed.

>>That is very time-consuming no
>> matter how you slice it, and it will always be slower than not using it.
>
> And yet almost always still faster than real time for all drives and CD's
> I
> have tried (dozens of drives and thousands of disks!)
> the only few exceptions are a couple of badly copy protected disks, and a
> couple of seriously damaged disks.

There you go. I think that is what my situation is.

>> And I did download and try EAC as soon as I had the opportunity. It is
> nice,
>> but it took about an hour to get through the first track and a half of
>> the
>> CD I'm having trouble with.
>
> And with the other CD's you have tried?
> Either your drive is poor, or you are simply trying to read a disk that
> has
> been deliberately made faulty in an attempt at copy protection.
> (that's my bet) Does the disk cover mention copy protection?

The cover does not mention it. I looked.

>>There might be something unusual about this CD,
>> but I feel that my claim of being hopelessly slow is vindicated.
>
> On that disk maybe, when you have tried a few dozen other disks, and
> perhaps
> another drive, get back to us.
> Of course I should mention that EAC needs to be set for your drive,
> something you may not be capable of, going by what you have posted so far.

You would be wrong then, but thanks for the insult.

>>Again, I'm
>> not blasting EAC, but when it has to read and compare each buffer up to
>> 32
>> times, that's going to take a while. It isn't an opinion, it's a
>> statement
>> of fact.
>
> And it's still a *WRONG* statement of fact for the VAST majority of drives
> and disks however.

This is from the EAC web site:
---
If an error occurs (read or sync error), the program keeps on reading this
sector, until eight of 16 retries are identical, but at maximum one, three
or five times (according to the selected error recovery quality) these 16
retries are read. So, in the worst case, bad sectors are read up to 82
times! But this effort will help the program to obtain the best result by
comparing all of the retries.
---
I had the number wrong, and of course, this is worst case. If the disc is in
good shape, then it will sail right through. My point was *again* if the
hardware provided redbook correction and better error reporting, the need
for this would be much less.

> I usually get secure rips at 10-20* real time.
> Just how much longer will you complain about one disk before admitting the
> problem is not with EAC?

How many times to I have to keep repeating that I am not saying there is a
problem with EAC? I am saying that with redbook correction/concealment, I
probably would not need EAC *for my purpose*. The disc would be listenable
enough for my needs, and for the needs of a great many people out there.
After all, I listened to that CD critically for years and the redbook
correction was good enough that I never noticed any problems. If I was
interested in getting bit-accurate copies, then I would disable concealment
(if the drive did concealment, and the option existed to disable it), and I
would put EAC to work on it.

> For all your whinging, it would be far easier to just connect your CD
> player
> output to your soundcard input, record in real time, and get on with life,
> if you are unable to get anything else to work!
> I have only ever needed to do that once in 1,000+ disks however.

Holy crap dude, for all my whinging [sic], I just wanted to know if CDROMs
do redbook error correction out of the SCSI/ATAPI interface, and was
expressing surprise that they didn't -- and -- here's the kicker: I was
looking at what EAC has to do (from a software developer's point of view --
I am one) and thinking that would be the hard way to do it, but probably the
best way, given the kind of data it has available to it.

I know full well how to get a usable copy from audio if I want to go that
route, or letting EAC chew on it overnight or for three days, or whatever it
takes.

I thought this would be an interesting place to discuss the features and
limitations of the hardware and software. Sorry I wasted your time.

[Mr.T]

"Karl Uppiano" > wrote in message
...
> I'm not sure what the point is with all the hostility. You write as if
I've
> been complaining about this for weeks in recurring threads. I brought it
up
> a day or two ago, and responded to some people.

And have made the same WRONG claims more than once with apparently NO notice
of what people have been telling you.

>It seems that the
> disc must be "denatured" somehow, and that's it.

You only own the one disk?

>What I still has not been
> answered to my satisfaction is if CD audio gets the same treatment --
> correction and concealment -- in CDROM drives that they do in audio
drives.
> I suspect that they do not, because the CD sounds fine in audio drives,
but
> not in the few CDROM drives that I checked.

Since you fail to compehend what has already been said on the matter,
further discussion would be pointless.
Try re-reading what you have been told, and doing some further reading of
your own on the subject then.

> I checked it in several other drives; I just didn't have a chance to
respond
> about that in all the discussion that you read (not in real time). Stop
> assuming I'm stupid or unwilling to change just because I haven't answered
> everyone's questions in your particular reading order!

It's your continued incorrect claims about CDROM drives that is the problem.

> Correction and concealment according to the redbook spec is what I'm
talking
> about. That hasn't been answered,

Yes it has.

>and if you don't want concealment, then
> fine, but I think it should be an available option.

It is done in software. YOU would be the only one happy if your programs
didn't work because your drive was happy to guess what the data *might* be.
You DO realise CDROM drives are not just about playing audio right?

> You missed my point. I said C1 and C2 correction can be done "at whatever
> rate real-time is when ripping". If that is 8x or whatever,

"REAL TIME" means only one thing, (1 hour for a 60 minute disk!)
How can 8 x real time be "real time", to anyone other than you anyway!

>then C1 and C2 correction can be done at that rate.
>It is a low overhead process, and works remarkably well.

Sure does, but why do you keep claiming CDROM drives do not have that
capability?
Some software can even tell you how many C1/C2 errors there are at a rate
much faster than real time.

> >>That is very time-consuming no
> >> matter how you slice it, and it will always be slower than not using
it.
> >
> > And yet almost always still faster than real time for all drives and
CD's
> > I have tried (dozens of drives and thousands of disks!)
> > the only few exceptions are a couple of badly copy protected disks, and
a
> > couple of seriously damaged disks.
>
> There you go. I think that is what my situation is.

As I originally guessed. Yet you kept claiming CDROM drives were inadequate,
or EAC.

>>Does the disk cover mention copy protection?
>
> The cover does not mention it. I looked.

Fine, but it may still use copy protection without stating it. Most early CP
disks did not until many people complained they could not play them.

> > Of course I should mention that EAC needs to be set for your drive,
> > something you may not be capable of, going by what you have posted so
far.
>
> You would be wrong then, but thanks for the insult.

You're welcome, you certainly brought it on by not listening to what you
were being told.

> > And it's still a *WRONG* statement of fact for the VAST majority of
drives
> > and disks however.
<snip EAC info you now accept>
> I had the number wrong, and of course, this is worst case. If the disc is
in
> good shape, then it will sail right through.

Which is exactly what I said. Only IF there is a read error will it need to
re-read the data with most drives.

>My point was *again* if the
> hardware provided redbook correction and better error reporting, the need
> for this would be much less.

Which again is bull****. The drive *does* provide full error correction as
necessary to red book, orange book and other standards as stated by the
manufacturer. And most drives do report when an error occurs. Why do you
continue to claim they don't?

The simple fact is that a modern CDROM drive is far better at *correcting*
errors than most CD audio players.

> How many times to I have to keep repeating that I am not saying there is a
> problem with EAC? I am saying that with redbook correction/concealment, I
> probably would not need EAC *for my purpose*.

No matter how many times you say it, you are still wrong. And you probably
DON'T need EAC for your purpose!

Here's a tip, since you do NOT want accurate data, go and get the freeware
program AUDIOGRABBER. It is non secure, but often faster, and will rip some
copy protected or faulty disks that EAC has problems with. And does not
bother you when it cannot provide accurate data.

> Holy crap dude, for all my whinging [sic], I just wanted to know if CDROMs
> do redbook error correction

And were told MANY times they do.

You seem to think CDROM drives are (or should be) made for the express
purpose of ripping audio disks. I'd hate to break it to you but it isn't so.
However most drives can manage it quite well considering the CDDA data
encoding scheme is not designed for block access like CDROM is.

Most people simply do not have the problems you do. Why do you think that is
so?
(hint, they probably learn what they are doing wrong)

MrT.