[Flac-dev] Improving on Rice coding

[Josh Coalson]

--- Paul Harrison <pfh at mail.csse.monash.edu.au> wrote:
> Hello,
> 
> I am the author of the Bonk audio compression program... i've just
> been
> looking at your comparrison table, and i noticed bonk gets marginally
> better compression than Flac on some files (actually i was
> rather surprised to see bonk on the list at all, it's not exactly
> high
> profile :-) ).

Paul, cool to see you here... I thought bonk was in limbo
since I couldn't even see the homepage for a while.

> Bonk in lossless mode is a pretty naive implementation of a
> predictive
> coder, so the main difference must be in the residual coding. Bonk
> uses
> an novel encoding that can adapt to the the distribution of
> prediction
> errors, wheras Flac uses Rice coding, which assumes a two tailed
> exponential distribution.
>
> Given that Flac is much more advanced in other respects, i wonder if
> you are interested in using bonk's encoding scheme?

I actually did study bonk a little when I discovered it.  I
didn't go far enough to attribute the compression differences
to prediction vs. residual.  Frankly your LPC analysis method
was over my head but I'm guessing the advantages have more to
do with the lossy aspect.

The residual coding method was interesting.  I guess I could
try popping it in.  The litmus test really for new methods is
1) is it unencumbered by patents; 2) is it fast enough decoding
to meet FLAC goals.  #2 is easy enough to verify; #1 is always
tricky.

> The relevant file is utility.h in
> http://yoyo.cc.monash.edu.au/~pfh/bonk/bonk-0.6.tar.gz. I've put a
> draft
> description of the encoder here:
> http://www.csse.monash.edu.au/~pfh/random/encoder.pdf

Cool, this doc is new to me.  I'll take a look.

Josh


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