[linux-audio-user] Flac vs wavpack and float32 to pcm24 conversion tests

Hi!

I'm interested in losless compression of typical Jack audifiles
for exchange. That means float32 sample format.

Flac doesn't handle float, only pcm.
wavpack handles both.

So I was told that converting from (wav) float32 to pcm24 and back
should be losless, if the float file is normalized. This would cut
down on file-size by itself and allow to use Flac.
I tested this using sndfile-convert and diff tells me there are
differences. The file sizes are identical.
diff did not report differences for a wav-unpacked file (staying
in float32).

Now I wonder if I did something wrong (I'm pretty sure the source
file is normalised), or if there's a bug in sndfile-convert or
if the differences are in the header. diff is a tool for text,
after all.

Anyways, file size results, didn't care about time:

48kHz, float 32:
- original wav: 59.1 MB (my Aliethno track)
- wavpack: 39.9 MB

pcm24:
- wav: 44.4 MB
- wavpack: 32.3 MB
- flac: 37.4 MB

I used wavpack -h and flac -8 for best compression ratios.
(Well, just saw wavpack has a -hh switch)

-- 
Thorsten Wilms
Thorwil's Creature Illustrations:
http://www.printfection.com/thorwil