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

[Gyan Doshi]

On 2022-04-27 02:38 am, Leo Izen wrote:
> Add more detailed documenation for the libjxl encoder
> wrapper than is present currently inside libavcodec.
> ---
>   doc/encoders.texi | 34 ++++++++++++++++++++++++++++++++++
>   1 file changed, 34 insertions(+)
>
> diff --git a/doc/encoders.texi b/doc/encoders.texi
> index aac9f25e55..99399d4674 100644
> --- a/doc/encoders.texi
> +++ b/doc/encoders.texi
> @@ -1809,6 +1809,40 @@ by ":". See the SVT-AV1 encoder user guide for a list of accepted parameters.
>   
>   @end table
>   
> + at section libjxl
> +
> +libjxl JPEG XL encoder wrapper.
> +
> +Requires the presence of the libjxl headers and library during
> +configuration. You need to explicitly configure the build with
> + at code{--enable-libjxl}.
> +
> + at subsection Options
> +
> +The libjxl wrapper supports the following options:
> +
> + at table @option
> +
> + at item distance
> +Set the target Butteraugli distance. This is a quality setting: lower
> +distance yields higher quality, with distance=1.0 roughly comparable to
> +libjpeg Quality 90 for photographic content. Setting distance=0.0 yields
> +true lossless encoding. Valid values range between 0.0 and 15.0, and sane
> +values rarely exceed 5.0. Setting distance=0.1 is usually attains
> +transparency for most input. The default is 1.0.
> +
> + at item effort
> +Set the encoding effort used. Higher effort values produce more consistent
> +quality and usually produces a better quality/bpp curve, at the cost of
> +more CPU time required. Valid values range from 1 to 9, and the default is 7.
> +
> + at item modular
> +Force the encoder to use Modular mode. The default is to let the encoder pick
> +between VarDCT and Modular encoding modes based on encoding settings and the
> +type of input content.

What happens in these two modes? Why would the user want to force 
modular? Is there a way and reason to force VarDCT?

Regards,
Gyan