[FFmpeg-devel] [PATCH] G.729A (floating-point) decoder and ACT demuxer

Vladimir Voroshilov voroshil
Tue Feb 26 04:11:07 CET 2008

Hi, Michael

On Tue, Feb 26, 2008 at 3:09 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Mon, Feb 25, 2008 at 08:53:44PM +0600, Vladimir Voroshilov wrote:
>  > On Sun, Feb 24, 2008 at 11:48 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>  > >


>  > >  Why would we choose the floating point approximation if we can have an
>  > >  exact integer implementation ?
>  >
>  > My skills are enough only for either cleanup current (working)
>  > floating-point code or 'port' (remove globals, fix data types, write
>  > interface to FFmpeg internals) reference code to ffmpeg.
>  > Thus, in fixed-point case, code will be 95% the same as reference.
>  Where is the problem with taking the L1/L2/L3 tables from the fixed point
>  implementation? They should be the same as the float ones obviously just
>  with different scaling.

They (float and converted fixed-point)  differs starting from 4th of
5th sign after comma.

>  Have you tried? Does it fail? Are you too lazy to try?

I didn't tried to use tables 'as-is' (i converted them to float first)
and they of course works. Just thought that reference float tables
will be more precise in floating point code.

I can't say  right now are they really better in current floating code
or not, because
removed them (while fixing error) before i found last error.

I'l try to put those tables back.
I should compare differences (both float and fixed-point tables) with
results of
fixed-point reference code, right?

I'll do checks as soon as possible and give you results of tiny_psnr, ok ?

Vladimir Voroshilov     mailto:voroshil at gmail.com
JID: voroshil at gmail.com, voroshil at jabber.ru
ICQ: 95587719

More information about the ffmpeg-devel mailing list