Re: [FFmpeg-devel] [crop support for matroska demuxer, V3 1/3] libavcodec: Add crop related fields to structure AVCodecContext and AVCodecParameters.

[Anton Khirnov <anton@khirnov.net>]

Quoting OvchinnikovDmitrii (2022-10-07 16:59:40)
> ---
>  libavcodec/avcodec.h       | 35 +++++++++++++++++++++++++++++++++++
>  libavcodec/codec_par.h     |  8 ++++++++
>  libavcodec/options_table.h |  4 ++++
>  3 files changed, 47 insertions(+)
> 
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index 7365eb5cc0..d28a7cc022 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -380,6 +380,19 @@ typedef struct RcOverride{
>   */
>  #define AV_GET_ENCODE_BUFFER_FLAG_REF (1 << 0)
>  
> +/**
> +* Video decoding only. Certain container support cropping, meaning that
> +* only a sub-rectangle of the decoded frame is intended for display.
> +* Certain codec supports cropping as well.This option controls how
> +* cropping is handled by libavcodec when  container cropping and
> +* codec cropping exist.
> +*/
> +enum CONTAINER_CROPPING_POLICY_TYPE {
> +    FF_CONTAINER_CROPPING_IGNORE = 0,
> +    FF_CONTAINER_CROPPING_ADDITION,
> +    FF_CONTAINER_CROPPING_OVERWRITE
> +};
> +
>  struct AVCodecInternal;
>  
>  /**
> @@ -2057,6 +2070,28 @@ typedef struct AVCodecContext {
>       *             The decoder can then override during decoding as needed.
>       */
>      AVChannelLayout ch_layout;
> +
> +    /* When set to 1 (the default), libavcodec will apply container cropping
> +     * to codec cropping additionally.
> +     *
> +     * When set to 2, libavcodec will use container cropping to overwrite
> +     * codec cropping (the final cropping uses container cropping parameters)
> +     *
> +     * When set to 0, libavcodec will ignore container cropping parameters
> +     * (the final cropping uses codec cropping parameters)
> +     *
> +     * This field works with "apply_cropping". Only if apply_cropping is 1, this
> +     * field works
> +     */
> +    enum CONTAINER_CROPPING_POLICY_TYPE container_apply_cropping;
> +
> +    /**
> +     * The cropping parameters from container.
> +     */
> +    int container_crop_top;
> +    int container_crop_left;
> +    int container_crop_bottom;
> +    int container_crop_right;

I don't see why should a decoder deal with this at all? This can be just
as well done by the caller.

-- 
Anton Khirnov
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