[FFmpeg-devel] [PATCH] Move lpc utility code from flacenc.c to lpc.{c|h}

[Jai Menon]

Hi,

On Friday 15 Aug 2008 4:44:35 pm Michael Niedermayer wrote:
> On Fri, Aug 15, 2008 at 03:07:12PM +0530, Jai Menon wrote:
> > Hi,
> >
> > On Friday 15 Aug 2008 2:58:15 pm Ramiro Polla wrote:
> > > Hi,
> > >
> > > On Fri, Aug 15, 2008 at 3:14 AM, Jai Menon <realityman at gmx.net> wrote:
> > > > Attached patch moves a few functions from the flac encoder so that it
> > > > can be shared by the alac encoder.
> > >
> > > For MLP I used the entire lpc_calc_coefs(). Is that not ok for alac?
> >
> > No, currently the order estimation does not require such extensive code.
> > It doesn't really help with compression or speed. A simpler approach is
> > used instead.
>
> please also use lpc_calc_coefs()
>

Its just that for the first iteration of the encoder which I hope will end up 
in FFmpeg-svn, I'm planning to keep the order selection simple. The 
approach(in so-svn) gives pretty good compression (better than dbpoweramp 
always, slightly lesser than itunes). We just need to quantize either 4th or 
6th order lpc coeffs. If I use the stock lpc_calc_coeffs, I'll have to make 
use of the EST method which will quantize all coeffs upto 6th order. This 
ends up being suboptimal. I didn't reuse lpc_calc_coefs because the speed 
tradeoff is significant.

> > > And the functions should be prefixed with ff_, and lpc.c be made as an
> > > svn cp ; svn diff from flacenc.c
> >
> > ...and is there any particular reason/advantage for using 'svn cp'?
> > Just curious.
>
> "svn blame" cannot relate lines of code to authors&commits if svn cp hasnt
> been used
>

Ah, okay. I didn't think of it that way :-)

Regards,

Jai Menon