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Topic: iTunes WAV to AIFF (and vice versa) conversion (Read 3292 times) previous topic - next topic
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iTunes WAV to AIFF (and vice versa) conversion

Perhaps this has been covered before, but after searching for some time, I was unable to find a relevant topic.

I am curious the extent of file processing taking place when converting from one uncompressed format (such as wav) to another (such as aiff.) To the best of my knowledge, WAV and AIFF are simply container formats, both storing PCM audio. So "converting" between the two, should not recalculate anything, simply add the neccesary headers. But, how true is my assumption? This also brings me to another topic..

How "good" is iTunes' CD ripper compared to something like Exact Audio Copy? Perhaps all of these are silly questions, but what really threw me off is the amount of options under "WAV Encoder" and "AIFF Encoder" in iTunes' preferences. I started thinking if these "encoders" were indeed simply bit transparent extractors, none of these options would be present..

Thanks in advance for any replies!

iTunes WAV to AIFF (and vice versa) conversion

Reply #1 –
I am not sure about the actual differences between AIFF and WAV so I won't comment on that.  I do know that on my old 2002 desktop (P4 2GHz with 256MB of RAM), iTunes is able to transcode from a WAV to AIFF file at around 50X encoding speeds.

I do know that the iTunes CD ripper does not have the same secure ripping options that EAC does.  I think iTunes uses a "jitter" correction system which is pretty common.  Additionally, if there is a audio flaw (such as a crack or beep) on the CD due to a scratch, iTunes will simply just encode that into the resulting ripped file (such as AAC, mp3, WAV, AIFF, etc.).  EAC will not do this without notifying you that your CD has some major error.

iTunes WAV to AIFF (and vice versa) conversion

Reply #2 –
Quote from: djczar on
I am curious the extent of file processing taking place when converting from one uncompressed format (such as wav) to another (such as aiff.) To the best of my knowledge, WAV and AIFF are simply container formats, both storing PCM audio. So "converting" between the two, should not recalculate anything, simply add the neccesary headers. But, how true is my assumption? This also brings me to another topic..

WAV and AIFF both contain PCM data, but WAV generally stores the PCM data in little-endian format while AIFF stores PCM data in big-endian format.  It is possible to have a WAV with big-endian data (RIFX) but they are more the exception than the rule.  So to convert from one to the other probably requires some byte-swapping (but may not depending on the bits per sample) and then writing the header and format information.

iTunes WAV to AIFF (and vice versa) conversion

Reply #3 –
Quote from: sbooth on
WAV and AIFF both contain PCM data, but WAV generally stores the PCM data in little-endian format while AIFF stores PCM data in big-endian format.  It is possible to have a WAV with big-endian data (RIFX) but they are more the exception than the rule.  So to convert from one to the other probably requires some byte-swapping (but may not depending on the bits per sample) and then writing the header and format information.

Thanks for the reply! I was suspecting something like that was going on. Now if I want to stay as close to the original CDDA audio as possible, should I rerip everything from CD to AIFF directly? Or, are these big/small endian changes just on a file system level, not affecting the actual PCM material?

If lets say a WAV file is loaded into an audio editor (Pro Tools, Cubase, Acid, whatever,) and then simply ouput back to wav with same specs as original, the software will recalculate the entire file, correct? So even if we're dealing with digital audio here, you do this enough times and something will sound different... Or am I wrong? Thanks again.

iTunes WAV to AIFF (and vice versa) conversion

Reply #4 –
Converting WAV to AIFF simply alters the arrangement in which the audio is stored - not the audio itself.

Quote
If lets say a WAV file is loaded into an audio editor (Pro Tools, Cubase, Acid, whatever,) and then simply ouput back to wav with same specs as original, the software will recalculate the entire file, correct? So even if we're dealing with digital audio here, you do this enough times and something will sound different... Or am I wrong?

You're wrong.

(Of course, my answers do not account for major problems with the pieces of software concerned or their implementations )

iTunes WAV to AIFF (and vice versa) conversion

Reply #5 –
Converting between little and big-endian is a lossless procedure.