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Topic: Difference between CD vs. Lossless copy (Read 9210 times) previous topic - next topic
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Difference between CD vs. Lossless copy

I know just by the title that a bunch of you are wanting to rip my head off and say something like "There is no difference between sound quality on CD and a lossless copy." Don't worry, that isn't my question exactly.

Is there any actual difference between playing a CD on your computer verse playing an accuraterip, offset corrected, secure lossless rip from that CD? The reason I ask is because I understand that CDs end up with scratched, errors, etc. If you're playing a CD that contains errors (bad sectors or something) would that mean that it's "worse" than a ripped CD that has been ripped correctly with dBpoweramp or EAC? Those errors aren't corrected when playing the CD, right? Wouldn't that technically make the ripped copy superior?

Difference between CD vs. Lossless copy

Reply #1 –
I suspect that this might answer your question.

From http://3aaa.org/ripping-technique.html


What does a CD player do when it finds an error?

When a CD player recognizes an audio track, it routes the bit stream to its DAC - digital-to-analogue converter. There the minimal layer of error correction is applied to patch up some errors in a disc that's in good shape (it cannot do much more) and the analogue sound output is generated.

Therefore, in theory a digital extracted CD played by your computer hard disk can be of a higher quality than the original CD played by your CD-player! If you want to achieve this you need to know your CD-ROM/DVD DAE drive features.

Difference between CD vs. Lossless copy

Reply #2 –
There are three layers of error correction in CD playback. The first two are 100%, they give back exactly what was written on the CD. The third layer, for more difficult cases, attempts to generate what was probably on the CD; there isn't enough information left to be positive. This result can be anything from undetectably good to really terrible, depending on how bad the problem is.

If the problem is bad enough for some of these "secure" extraction methods to really earn their keep, the error is probably bad enough to reach the third layer is a CD player. The computer extraction may do a better job than the CD player but it certainly isn't guaranteed.

Difference between CD vs. Lossless copy

Reply #3 –
I've had a handful CD's with damage that sound better when played thought my CD player than they do with a secure rip. The CD player seems to do a better job of covering up the errors in these few cases than EAC secure with AccurateRip. A couple had deep scratches, the rest were manufacturing flaws. The sound isn't perfect, there are just no noticeable stutters, clicks or dropouts as with the ripped file.

Rather than stress over it, if I can't get a decent rip, I just buy another copy of the CD.

On a side note, I buy CD's every week, and nothing annoys me more than the poor quality of recent pressings.

Too many times I have opened factory sealed CD's to find scratches, cloudy areas, bubbles in the plastic and even pinholes in the metal coating. These are from major retailers, first run! Of course I take them back when I can, but it's still a pain.
EAC secure | FLAC  --best -V -b 4096 | LAME 3.97 -V0 -q0 -b32

Difference between CD vs. Lossless copy

Reply #4 –
Quote from: UrbanVoyeur on
The CD player seems to do a better job of covering up the errors in these few cases than EAC secure with AccurateRip.

when this is the case, try doing a few "burst" mode rips, they are a lot closer to the type of extraction a CD player does, and can give better results for bad scratches.

also try (as a VERY last resort) windows media player, or a few other more basic rippers.

but usually one of EAC's modes will do a decent, normally better job than most CD players.

Difference between CD vs. Lossless copy

Reply #5 –
I think one needs to distinguish between two different ways of playing back a CD in a computer. You can either use the analog output of the drive, connected to your sound card through a cable, or else digitally by reading the digital data into the CPU and then outputting that to the sound card. In the former case the results may be similar to playing the CD on a standalone player, with missing or corrupt data being replaced by the drive. In the latter case the digital data read by the drive, right or wrong, are sent to the sound card with no further correction. This is likely to be the worst case of all.

Difference between CD vs. Lossless copy

Reply #6 –
Quote from: trev on
when this is the case, try doing a few "burst" mode rips, they are a lot closer to the type of extraction a CD player does, and can give better results for bad scratches.


Yes, burst mode has helped in about 1/2 the cases. Though not quite as effective as a new, undamaged CD. ;-)
EAC secure | FLAC  --best -V -b 4096 | LAME 3.97 -V0 -q0 -b32

Difference between CD vs. Lossless copy

Reply #7 –
Quote
I've had a handful CD's with damage that sound better when played thought my CD player than they do with a secure rip. The CD player seems to do a better job of covering up the errors
  I've had the same results.  I've never run across the opposite situation where a rip sounded better than the actual CD.  It seems to me the player's software/firmware (even in a cheap player) is better at error-hiding than any ripping software!  When all else fails, an analog-rip is my last resort.

Difference between CD vs. Lossless copy

Reply #8 –
There's error correction and error concealment (like AndyH-ha said). Audio CDs have blurred the distinction between them aiming for transparent playback, but not necessarily perfect result.

There may be a way to rip using S/PDIF connection instead of analogue. CD drives used to have SPDIF output and rackmountable dedicated CD players almost always have some type too.

Difference between CD vs. Lossless copy

Reply #9 –
Quote from: j7n on
Audio CDs have blurred the distinction between them aiming for transparent playback, but not necessarily perfect result.

The distinction isn't blurred.  Audio CDs only have two layers of error correction.  If data cannot be corrected then the player will (hopefully) make an attempt to conceal the error.

http://en.wikipedia.org/wiki/Cross-interle...-Solomon_coding

Difference between CD vs. Lossless copy

Reply #10 –
Exactly. And just to add, concealment is done by either interpolating the missing (or wrongly read) samples or muting the output. Of course, the first method is preferred and can be pretty transparent.
If age or weaknes doe prohibyte bloudletting you must use boxing

Difference between CD vs. Lossless copy

Reply #11 –
Hehe, you're all missing one important thing here, if not the most important one.

Playing back the Audio CD back directly will in most cases sound very unpleasant unless you limit the read speed of the drive.

Difference between CD vs. Lossless copy

Reply #12 –
Does EAC any concealement at all?

I read the specs of a Philips CD-chip a few years ago. It concealement was simply:
1. If single sample error: interpolate
2. If >1 burst error, hold last good sample


I imagine that all sorts of voodoo methods are possible, just like clipping concealement? Short frequency analysis immidiately before and after error, large filter, etc. In the end, information is lost, but you know that it is. The rest is just modelling the source and/or the listener so as to minimize the perceived error.

-k

Difference between CD vs. Lossless copy

Reply #13 –
Does EAC even get enough information to perform concealment? Do drives report that a single sample is in error, and which one? Do some drives work this way and others not?

Difference between CD vs. Lossless copy

Reply #14 –
Yes, it is called c2 error pointers.

Difference between CD vs. Lossless copy

Reply #16 –
Isn't there already specialized software to conceal clicks and pops in unconcealed errorneus rips? If the license permits it, why not simply add those apps to the ripper-package, and then add an option in the GUI which runs that software if errors were found during a rip? One could even ask the devs of those apps if they are interested in cooperation - since the ripper KNOWS where the errors happened and could report that info to the concealer-app.
I am arrogant and I can afford it because I deliver.

Difference between CD vs. Lossless copy

Reply #17 –
If not, I guess that would be a big reason why some users experience differences in sound quality - especially those that arent interested in reading logs or using accuraterip, just choosing EAC because it is considered to be "the best"?

-k

Difference between CD vs. Lossless copy

Reply #18 –
Quote from: Fandango on
Hehe, you're all missing one important thing here, if not the most important one.

Playing back the Audio CD back directly will in most cases sound very unpleasant unless you limit the read speed of the drive.

If CD is played directly using either analog or SPIDF output, it will run at 1x or 2x speed already.

Difference between CD vs. Lossless copy

Reply #19 –
What is considered the generally "best" way to conceal one or a few missing/errouneous samples?`

-k

Difference between CD vs. Lossless copy

Reply #20 –
Quote from: knutinh on
What is considered the generally "best" way to conceal one or a few missing/errouneous samples?`
The algorithms that CEDAR use for filling in lost audio at loud clicks in LPs. There are various techniques...

http://www-sigproc.eng.cam.ac.uk/%7Esjg/springer/index.html

...a 346 page book for free can't be bad!

Cheers,
David.