[Ffmpeg-devel] [PATCH] Which Vorbis encoder by default

Oded Shimon ods15
Tue Oct 3 21:08:14 CEST 2006

On Tue, Oct 03, 2006 at 08:53:18PM +0200, Michael Niedermayer wrote:
> On Tue, Oct 03, 2006 at 08:20:00PM +0200, Oded Shimon wrote:
> > On Tue, Oct 03, 2006 at 03:30:18PM +0200, Diego Biurrun wrote:
> > > That's perfectly OK, but independent of adding native to the name of our
> > > encoder .. :)
> > 
> > So what do you suggest for the case of ffmpeg compiled with libvorbis, yet 
> > still wanting to use my encoder?
> > The idea is that the codec named "vorbis" depends on if ffmpeg was 
> > compiled with libvorbis or not, and some other name, will always point to 
> > my encoder.
> id suggest that we drop libvorbis support and you hurry a little with
> improving quality of your encoder

I'm at a dead end :(

> see google/wikipedia/citeseer/source code of other encoders for 
> psychoacoustics for example
> and support for both blocksizes is also a must

I've read lots of wikipedia stuff on psy, and as much as I can from 
libvorbis source, and reached a conclusion that this stuff is way out of 
my league. :(
I understand some of the basic ideas there, but my knowledge of even basic 
things such as fft is so weak (I only know how to implement it and use it 
and what it's useful for, but I don't really understand it) that I can't 
implement the ideas given there in any usable way...

Any volunteers to help me? :)

> IMHO the encoder should have some sort of distortion measure
> function (in reality that will be just a weighted sum of squares
> where the weights for different coefficients come from the psycoacoustic
> model)
> and then just minimize rate(=number of bits) + distortion * quality(=constant)

I think this method doesn't apply as well to audio as it does to video... 
You can't play guessing games with the quantization because you can change 
it anywhere to anything, as opposed to being a global constant (for the 
single frame)...

- ods15

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