[FFmpeg-devel] [Internet][PATCH 1/6] avcodec/cbs: add API to discard units by AVDiscard

["zhilizhao(赵志立)"]

Ping. Any comments on the idea?

> On May 18, 2023, at 05:23, Zhao Zhili <quinkblack at foxmail.com> wrote:
> 
> From: Zhao Zhili <zhilizhao at tencent.com>
> 
> ---
> libavcodec/cbs.c          | 21 +++++++++++++++++++++
> libavcodec/cbs.h          | 17 +++++++++++++++++
> libavcodec/cbs_internal.h |  6 ++++++
> 3 files changed, 44 insertions(+)
> 
> diff --git a/libavcodec/cbs.c b/libavcodec/cbs.c
> index 504197e06d..cf5211249b 100644
> --- a/libavcodec/cbs.c
> +++ b/libavcodec/cbs.c
> @@ -1026,3 +1026,24 @@ int ff_cbs_make_unit_writable(CodedBitstreamContext *ctx,
>     av_buffer_unref(&ref);
>     return 0;
> }
> +
> +void ff_cbs_discard_units(CodedBitstreamContext *ctx,
> +                          CodedBitstreamFragment *frag,
> +                          enum AVDiscard skip,
> +                          int flags)
> +{
> +    if (!ctx->codec->discarded_unit)
> +        return;
> +
> +    for (int i = frag->nb_units - 1; i >= 0; i--) {
> +        if (ctx->codec->discarded_unit(ctx, &frag->units[i], skip)) {
> +            // discard all units
> +            if (!(flags & DISCARD_FLAG_KEEP_NON_VCL)) {
> +                ff_cbs_fragment_free(frag);
> +                return;
> +            }
> +
> +            ff_cbs_delete_unit(frag, i);
> +        }
> +    }
> +}
> diff --git a/libavcodec/cbs.h b/libavcodec/cbs.h
> index ee21623dac..b4131db5fe 100644
> --- a/libavcodec/cbs.h
> +++ b/libavcodec/cbs.h
> @@ -26,6 +26,7 @@
> 
> #include "codec_id.h"
> #include "codec_par.h"
> +#include "defs.h"
> #include "packet.h"
> 
> 
> @@ -432,5 +433,21 @@ int ff_cbs_make_unit_refcounted(CodedBitstreamContext *ctx,
> int ff_cbs_make_unit_writable(CodedBitstreamContext *ctx,
>                               CodedBitstreamUnit *unit);
> 
> +enum CbsDiscardFlags {
> +    DISCARD_FLAG_NONE = 0,
> +
> +    /**
> +     * keep non-vcl units even if the picture has been dropped.
> +     */
> +    DISCARD_FLAG_KEEP_NON_VCL = 0x01,
> +};
> +
> +/**
> + * Discard units accroding to 'skip'.
> + */
> +void ff_cbs_discard_units(CodedBitstreamContext *ctx,
> +                          CodedBitstreamFragment *frag,
> +                          enum AVDiscard skip,
> +                          int flags);
> 
> #endif /* AVCODEC_CBS_H */
> diff --git a/libavcodec/cbs_internal.h b/libavcodec/cbs_internal.h
> index e585c77934..077954eee5 100644
> --- a/libavcodec/cbs_internal.h
> +++ b/libavcodec/cbs_internal.h
> @@ -133,6 +133,12 @@ typedef struct CodedBitstreamType {
>                       CodedBitstreamUnit *unit,
>                       PutBitContext *pbc);
> 
> +    // Return 1 when the unit should be dropped according to 'skip',
> +    // 0 otherwise.
> +    int (*discarded_unit)(CodedBitstreamContext *ctx,
> +                          const CodedBitstreamUnit *unit,
> +                          enum AVDiscard skip);
> +
>     // Read the data from all of frag->units and assemble it into
>     // a bitstream for the whole fragment.
>     int (*assemble_fragment)(CodedBitstreamContext *ctx,
> -- 
> 2.25.1
> 
> 
> 
>