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ALAC/FLAC converters (dbpoweramp, Audacity, Xrecode, iTunes) output a different file size.

post #1 of 6
9/12/12 at 3:17pm
Thread Starter 

Since I'm picky, I've tested different audio converters.

 

From the same AIFF audio file each converter outputs a different ALAC file size:

iTunes=11.956.256

dbpoweramp=11.923.869

Xrecode=11.921.156

 

From another FLAC file to AIFF:

dbpoweramp=19.075.432

Xrecode=19.075.323

Audacity=18.997.502

 

and so on...

 

What's goin on?

Aren't they uncompressed or lossless format that can be converted without errors?

 

If each software handle them in a different way and outputs a different file size they are not perfect copy of the original.

 

If a software behave with some errors I can't think about doing it on the fly in hardware streaming renderers or dacs.

 

Any thoughts?


Edited by Thraex - 9/13/12 at 1:24am
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post #2 of 6
9/12/12 at 3:20pm

 The difference may just be tagging with one convertor or the other adding more non music meta data.


Edited by goodvibes - 9/12/12 at 3:22pm
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post #3 of 6
9/12/12 at 3:27pm

Try reversing the conversion and see if the files have the same MD5 hash.


Edited by Anda - 9/12/12 at 3:29pm
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post #4 of 6
9/12/12 at 3:29pm
Thread Starter 

Just tested.

If I use the same software I come back with same file size, if I change to a different software I can't have the original file size anymore:

dbpoweramp AIFF>ALAC>AIFF is the same

dbpoweramp AIFF>ALAC Xrecode ALAC>AIFF not the same as original

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post #5 of 6
9/12/12 at 3:53pm
Thread Starter 

I've just ripped a CD track, before I've disconnected internet and deleted any metadata info including "unknown", "track 1" inside dbp cd ripper, then I've edited again the AIFF file for metadata and cleared all info:

Xrecode ALAC=20.045.678

dbpoweramp ALAC=20.046.597

iTunes ALAC=20.057.274

 

Could you try with any software you have and report if at least two converters output the same file size?

 

P.S. How can I check MD5 hash?


Edited by Thraex - 9/12/12 at 4:14pm
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post #6 of 6
9/12/12 at 6:16pm
Thread Starter 

Further testing:

I was wrong regarding AIFF, if metadata are cleared, from FLAC to AIFF all the same file size.

If you convert to FLAC some software or setting could use a different compression so the different file size.

 

For ALAC the output is always different because some metadata fields are always written even if the source file is clear:

dbpoweramp=61.338.749 container: (nothing) and no tag at all.

Xrecode= 61.336.666 container: "ID TAG [Apple iTunes]", tags: "encofing tool" only.

iTunes= 61.398.420 container: "ID TAG [Apple iTunes]", tags: "title","Compilation","Encoding Tool",and others...

 

This is a clue but I'm still uncertain why dbpoweramp has a slightly bigger file than Xrecode which writes some metadata.

 

Is it possible instruct iTunes and Xrecode to clear all metadata while decoding to ALAC just to check if there isn't any difference?


Edited by Thraex - 9/13/12 at 1:25am
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Head-Fi.org › Forums › Equipment Forums › Computer Audio › ALAC/FLAC converters (dbpoweramp, Audacity, Xrecode, iTunes) output a different file size.