[FFmpeg-devel] [PATCH] Update trellis option usage in FAQ

[Stefano Sabatini]

On date Saturday 2008-11-15 08:37:43 -0800, Jason Garrett-Glaser encoded:
> On Sat, Nov 15, 2008 at 6:05 AM, Jethro Walters
> <turkeyman121 at yahoo.co.uk> wrote:
> > --- On Sat, 15/11/08, Michael Niedermayer <michaelni at gmx.at> wrote:
> >
> >> From: Michael Niedermayer <michaelni at gmx.at>
> >> Subject: Re: [FFmpeg-devel] [PATCH] Update trellis option usage in FAQ
> >> To: "FFmpeg development discussions and patches" <ffmpeg-devel at mplayerhq.hu>
> >> Date: Saturday, 15 November, 2008, 12:05 PM
> >> > > On Sat, Nov 15, 2008 at 12:43:59PM +0100, Stefano Sabatini wrote:
> >> > Hi,
> >> >
> >> > since lavc 52 trell isn't anymore a valid flag, patch changes -flags
> >> > +trell with -trellis 2.
> >>
> >> hmm, it seems we are missing a description of what 0/1/2 is
> >> in avcodec.h and the AVOptions in utils.c
> >
> > Perhaps taking them from x264 CLI's long-help description would be appropriate. From memory it's something like the following (don't have x264 to hand at the moment, where's Dark Shikari when ya need him? ;-)):
> >
> > 0 - No trellis performed
> > 1 - Perform trellis on final macroblock encode only
> > 2 - Perform trellis on all encodes
> >
> > But that's just from memory, and is possibly a little inaccurate, and out-dated since x264 / Dark Shikari made changes to what trellis specifically did.
> >
> > Jethro Walters
> 
> Nope, trellis is the same as it always was.  "Psy trellis" was added
> as an option, but like AQ and psy-RD, its not accessible through lavc
> because nobody has added a commandline option for it in ffmpeg.

>From a quick grep (no I don't know what trellis algo really is) it
looks like trellis has a different meaning according to the codec
where it is used.

In mpegvideo_enc.c, lixbvidff.c and nellymoserenc.c it is used as a flag.

In adpcm.c its value ranges from 0 (disabled) to 16.

In libx264.c it is used to fill the libx264 context like this:
x4->params.analyse.i_trellis = avctx->trellis

so in this case its meaning is the same as defined in libx264.

Patch for libavcodec/utils.c attached.

Regards.
-- 
FFmpeg = Funny Free Minimalistic Powered Ecumenical Game
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