[FFmpeg-devel] [PATCH] doc/encoders: document libtheora encoder

[Stefano Sabatini]

On date Sunday 2012-11-11 14:46:13 +0100, Stefano Sabatini encoded:
> On date Sunday 2012-11-11 14:17:12 +0100, Clément Bœsch encoded:
> > On Sun, Nov 11, 2012 at 12:41:15PM +0100, Stefano Sabatini wrote:
> > > ---
> > >  doc/encoders.texi |   40 ++++++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 40 insertions(+)
> > > 
> > > diff --git a/doc/encoders.texi b/doc/encoders.texi
> > > index a7a2761..121d07b 100644
> > > --- a/doc/encoders.texi
> > > +++ b/doc/encoders.texi
> > > @@ -420,6 +420,46 @@ Selected by Encoder (default)
> > >  A description of some of the currently available video encoders
> > >  follows.
> > >  
> > > + at section libtheora
> > > +
> > > +Theora format supported through libtheora.
> > > +
> > > +Requires the presence of the libtheora headers and library during
> > > +configuration.  You need to explicitly configure the build with
> > > + at code{--enable-libtheora}.
> > > +
> > > + at subsection Options
> > > +
> > > +The following options are mapped to internal libtheora options which
> > 
> > The following /global/ options?
> 
> Changed.
> 
> > 
> > > +affect the quality and the bitrate of the encoded stream. All the
> > > +other global options are ignored.
> > 
> > Maybe "All the other global options /such as qmin or qmax/ ..." ?
> > 
> > But I'd better not say something such as this: at some point we might try
> > to honor more avctx settings in the wrapper and forget to update this
> > sentence. Maybe mitigate the sentence with "likely" or something.
> 
> I removed the sentence. In case a new mapping is added, we should
> update the docs and bump micro.
> 
> > 
> > > +
> > > + at table @option
> > > + at item b
> > > +Set the video bitrate, only works if the @code{qscale} flag in
> > > + at option{flags} is not enabled.
> > > +
> > > + at item flags
> > > +Used to enable constant quality mode encoding through the
> > > + at option{qscale} flag, and to enable the @code{pass1} and @code{pass2}
> > > +modes. All the other values are ignored.
> > > +
> > > + at item g
> > > +Set the GOP size.
> > > +
> > > + at item global_quality
> > > +Set the global quality in lambda units, only works if the
> > > + at code{qscale} flag in @option{flags} is enabled. The value is clipped
> > > +in the [0 - 10*@code{FF_QP2LAMBDA}] range, and then multiplied for 6.3
> > > +to get a value in the native libtheora range [0-63].
> > 
> 
> > Sounds like a more general global-quality-expression-for-libs would be
> > welcome…
> 
> Unrelated.
>  
> > > +
> > > +For example, to set maximum constant quality encoding with
> > > + at command{ffmpeg}:
> > > + at example
> > > +ffmpeg -i INPUT -flags qscale -global_quality "10*QP2LAMBDA" -codec:v libtheora OUTPUT.ogg
> > > + at end example
> > > + at end table
> > > +
> > 
> > And so -qscale option has no effect?…
> 
> -qscale was never an option. -flags qscale is required to force CQR
> (constat quality rate) vs. CBR mode (constant bit rate) mode. The
> alternative is to use -q:v 10 but I prefer to show a more explicit
> option setting (which does not depend on the ffmpeg.c implementation).
> 
> Updated.
> -- 
> FFmpeg = Fabulous & Frightening Minimal Powered Extroverse Geek

> From 5839ac39cf12df011ed09758c55e7fcdcf348a24 Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefasab at gmail.com>
> Date: Sun, 11 Nov 2012 12:40:46 +0100
> Subject: [PATCH] doc/encoders: document libtheora encoder
> 
> ---
>  doc/encoders.texi |   39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
[...]

Applied.
-- 
FFmpeg = Free and Fabulous Marvellous Pure Enlightened God