From: Bryan Jacobs <no_at_landwarsin.asia>
Date: Sat, 20 Jun 2009 19:56:08 -0400

I'm a little behind this week -_-.

I started writing a multifile buffering interface allowing a codec to
devote flexible fractions of its buffer space to different files.
Halfway through this, paranoia struck: I never CHECKED that the audio
coming out of the codec I implemented last week was lossless!

I searched for some way to easily compare audio files but didn't find
one matching what I wanted, so I wrote my own:

http://www.q3q.us/wavdiff.c . This program dumps the headers from WAV
files and then compares them sample by sample, reporting any samples
that don't match.

I then went and double- and triple- checked the output from my codec.
Turns out I'd forgotten a ten-line code chunk so all Wavpack blocks
(except the first one, which I'd checked last week!) were decoding
incorrectly and falling back to hybrid lossy. This is fixed and I also
made a few improvements to the codec itself. As they say, you're only
paranoid if the world isn't out to get you :-P.

The updated version, which produces files 100% identical to those spat
out by wvunpack, is at:

http://www.q3q.us/hybrid2.patch .

This still can only run on the PC, not a real target. Since I'm well
on my way to having a better buffering interface, I should be able to
have at least sim builds playing sweet lossless sound by the end of
next week.

Enjoy, all!

Bryan Jacobs

Received on 2009-06-21