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-   -   Copying music files (http://www.avsforum.com/forum/91-audio-theory-setup-chat/1520552-copying-music-files.html)

Heinrich S 03-02-2014 06:02 AM

I've heard some people say that copying music on to their computers alters the sound quality of the music.

Is this possible?

Can copying a CD be done easily bit for bit without altering the music? And can music be ripped in such a way that it does alter the sound quality?

With CD you know for certain the source is unmodified and still in the format it was released to the public, so it would be nice to be able to rip all my music without changing the sound quality of the music.

William 03-02-2014 06:05 AM

Have you ever copied a spreadsheet or a data file and the contents changed?

Have you ever un Zipped a spreadsheet or data file and the contents changed?

Heinrich S 03-02-2014 06:41 AM

Yes, but that's not music on a cd.

Terry Newton 03-02-2014 06:50 AM

No it can't be changed,it's digital.It is an exact copy.,unless you alter it in some way.

67jason 03-02-2014 06:53 AM

Quote:
Originally Posted by Heinrich S View Post

Yes, but that's not music on a cd.
The 1's and 0's that make up the bits don't care if its music or other type of data. Computers unlike olden day analog copiers are able to make 100% bit perfect copies of data for little to no cost in software.

EAC and dbpoweramp are wonderful programs to use to rip cds.

arnyk 03-02-2014 07:41 AM

Quote:
Originally Posted by Heinrich S View Post

I've heard some people say that copying music on to their computers alters the sound quality of the music.

Is this possible?

Depends how the copying is done. But this is another of those "People say the darndest things", There can be grain of truth, but the general rule is no changes except intentional changes.

Copying music files done the simplest, most obvious way by using the desktop file management utilities doesn't change the files. Change even one bit in a computer file, and the results could be catastrophic.
Quote:
Can copying a CD be done easily bit for bit without altering the music?

Yes. I've done this and checked it out technically pretty thoroughly, and bit perfect copying CDs is again the default, the simplest, easiest, most obvious thing.
Quote:
And can music be ripped in such a way that it does alter the sound quality?

Yes. For example if you rip a CD to a low bitrate MP3 this changes its sound quality. But, if you rip to a .wav of FLAC file, then there are no changes to sound quality.
Quote:
With CD you know for certain the source is unmodified and still in the format it was released to the public, so it would be nice to be able to rip all my music without changing the sound quality of the music.

Not only is it nice, its the way that it is generally done.

amirm 03-02-2014 08:36 AM

See the second post from me in this thread: http://www.avsforum.com/t/1394446/flacs-are-inferior-to-wavs

And if you have a lot of patience for infighting, the rest of the thread. biggrin.gif

Bottom line: the assumptions in the above posts are not correct. But very likely so are the claims of audio fidelity differences.

Heinrich S 03-02-2014 08:37 AM

Quote:
Originally Posted by amirm View Post

See the second post from me in this thread: http://www.avsforum.com/t/1394446/flacs-are-inferior-to-wavs

And if you have a lot of patience for infighting, the rest of the thread. biggrin.gif

Bottom line: the assumptions in the above posts are not correct. But very likely so are the claims of audio fidelity differences.

So you are saying? That copying a file digitally does not guarantee it being a 1:1 bit perfect copy?

amirm 03-02-2014 08:39 AM

Quote:
Originally Posted by Heinrich S View Post

So you are saying? That copying a file digitally does not guarantee it being a 1:1 bit perfect copy?
It does guarantee that it is 1:1 perfect copy. But a perfect copy does not mean that in analog domain, they would sound or look the the same on measurement gear. Digital audio reproduction is half digital, half analog. The digital part remains the same. The analog part may not. See this article I wrote on how it really works as opposed to assumed operation: http://www.madronadigital.com/Library/DigitalAudioJitter.html

Heinrich S 03-02-2014 08:48 AM

Quote:
Originally Posted by amirm View Post

It does guarantee that it is 1:1 perfect copy. But a perfect copy does not mean that in analog domain, they would sound or look the the same on measurement gear. Digital audio reproduction is half digital, half analog. The digital part remains the same. The analog part may not. See this article I wrote on how it really works as opposed to assumed operation: http://www.madronadigital.com/Library/DigitalAudioJitter.html

So you are saying that it is possible for me to rip a CD on to my hard drive bit perfect, and the disk can sound different to the ripped bit perfect data?

amirm 03-02-2014 08:52 AM

Quote:
Originally Posted by Heinrich S View Post

So you are saying that it is possible for me to rip a CD on to my hard drive bit perfect, and the disk can sound different to the ripped bit perfect data?
It is possible but very improbable.

Frank Derks 03-02-2014 09:02 AM

Don't count on a bit perfect copy of a cd. Recording from the spdiff output of a cd player can differ from ripping the same cd with the dvd/cd rom player in the computer.
The error correction level of redbook cd is simple not robust enough to ensure bit perfect copies 100% of the time.

Although I doubt the difference will be audible.

Frank Derks 03-02-2014 09:11 AM

A possible difference in sound due to jitter has noting to do with the (copied) file. If correlated jitter is present and audible the used dac is just poorly designed. Doesn't matter if spdiff, usb or hdmi is used.

amirm 03-02-2014 09:20 AM

Quote:
Originally Posted by Frank Derks View Post

A possible difference in sound due to jitter has noting to do with the (copied) file.
In the context of PC reproducing them, it can. Again, the explanation is in the other thread.
Quote:
If correlated jitter is preset and audible the used dac is just poorly designed. Doesn't matter if spdiff, usb or hdmi is used.
Unfortunately by that definition, all mass market DACs are poorly designed smile.gif. Here is an example of a $1,000 AVR when fed the same file over S/PDIF and HDMI -- two digital interfaces that provided the same "bits" to the DAC in the AVR:

i-QHffrnc.png

Clearly the DAC did not manage to filter out the much increased jitter over HDMI. Same story exists for the other AVRs I tested.

Jitter reduction in these devices occurs in too high a frequency. That is adequate for proper recovery of data, but not enough to filter out jitter in audio band.

Heinrich S 03-02-2014 09:37 AM

I'm confused now. So copying bit perfect music may or may not result in an audibly perfect copy of the CD? Some people were saying it was a slam dunk, now others are saying it's not really true. eek.gif

Frank Derks 03-02-2014 09:43 AM

Imo virtually all dacs are flawed by design since true multibit dacs where replaced by oversampling and bitstream design.
Sadly the sample and hold circuits resampling the dac outputs and steep analog filters where abandoned very early in the cd era.

I can understand that proper clock reconstruction from a hdmi signal can easily go wrong. (the spdiff input is in the graph is poor too.)

However only in severe cases this would become audible.


And it has nothing to do with the copying of the cd itself.

wrat 03-02-2014 09:45 AM

http://www.exactaudiocopy.de/

Frank Derks 03-02-2014 09:54 AM

Don't be confused. 'bit perfect' is overrated. If due to a scratch or dust spec on the cd the error correction will first attempt to reconstruct with the redundant bits and if that fails interpolate the missing bits. If all else fails the output will be muted.

You can use a cd ripper program that uses Accuaterip http://www.accuraterip.com/

Heinrich S 03-02-2014 09:58 AM

Quote:
Originally Posted by Frank Derks View Post

Don't be confused. 'bit perfect' is overrated. If due to a scratch or dust spec on the cd the error correction will first attempt to reconstruct with the redundant bits and if that fails interpolate the missing bits. If all else fails the output will be muted.

You can use a cd ripper program that uses Accuaterip http://www.accuraterip.com/

Okay, but I'm talking about changes in sound quality. You are saying that the sound quality itself of the music won't change if a bit perfect copy was ripped on to a hard drive? So all that will happen if there was issues is muted output?

So the ability to have bit perfect copies of music has been around since the advent of the digital age? Perhaps I've been living under a rock. rolleyes.gif

sivadselim 03-02-2014 10:13 AM

Quote:
Originally Posted by Heinrich S View Post

Perhaps I've been living under a rock. rolleyes.gif

Well, that IS where trolls live.

Frank Derks 03-02-2014 10:13 AM

No changes in sound quality once it hits the hard drive. Hard drive storage is much more robust than that of an audio cd.

Frank Derks 03-02-2014 10:15 AM

I would say the potential was there all along. However during the advent of the digital music era home pc and digital copying was simply not there. We were fooling around with tape back then.

Heinrich S 03-02-2014 10:49 AM

So for how many years have we been able to copy digitally bit for bit copies of music? More than 15 years?

Frank Derks 03-02-2014 11:03 AM

Hard to tell. Does It matter?

15 years ago I just bought the cd and put it in a player.

Now I'm streaming them from a nas.

amirm 03-02-2014 12:03 PM

Quote:
Originally Posted by Heinrich S View Post

I'm confused now. So copying bit perfect music may or may not result in an audibly perfect copy of the CD? Some people were saying it was a slam dunk, now others are saying it's not really true. eek.gif
The issue of copying a CD is different than copying of a file on hard disk. The former requires reading the bits from CD correctly. Reading CDs reliably can be challenging. There is a ton of data on the net on that. Here is a good read from a tool people who worry about this use: http://www.dbpoweramp.com/secure-ripper.htm

Your original question asked if copying a file on the hard disk changes the sound. I explained this in post #2 of the other thread. Briefly, both bits are identical. But the process of reading them by the operating system and your media player is not. The system activity changes when accessing one file vs another. Such a change can modify the noise or timing of the clock pulses being fed to an external device. And that can eventually show up in the DAC output. Therefore we can NOT use the reasoning that "bits are bits" and therefore there cannot be a difference. That only deals with half the equation.

As a practical matter, I said that you should not worry at all about the second scenario of copying files around. Just don't use the "bits are bits" explanation for why that is the case. There is a lot more to it that I explained in the other thread.

For the CD one, if you have marginal discs, scratches, etc. then the better tools than the one that came with your media player will likely create a better rip.

goneten 03-02-2014 01:25 PM

So verifying that the audio file is a 1:1 copy is easy to do, but playing it back using different media players can affect the sound quality. I've heard people claim that just ripping the files to their hard drives alters the sound quality of the music. Die-hard audiophiles claim this. smile.gif


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