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

[Clément Bœsch]

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?

> +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.

> +
> + 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…

> +
> +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?…

[...]

-- 
Clément B.
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