Re: [FFmpeg-devel] [PATCH] lavc/vvc: Always set flags for the current picture

[Nuo Mi <nuomi2021@gmail.com>]

On Mon, Jun 24, 2024 at 11:30 PM Frank Plowman <post@frankplowman.com>
wrote:

> ff_vvc_frame_rpl uses the flags to detect whether a frame is in use.
> Therefore, in the case of a CVSS AU (RASL/GDR with
> NoOutputBeforeRecoveryFlag) with ph_non_ref_pic_flag = 1, the frame
> would be freed before it is used.  Fix this by always marking the
> current frame with VVC_FRAME_FLAG_SHORT_REF, as is done by the HEVC
> decoder.
>
> Additionally, add an assert0 to mitigate the effects of a frame being
> freed before it is used.
>
> Signed-off-by: Frank Plowman <post@frankplowman.com>
> ---
>  libavcodec/vvc/refs.c   | 2 +-
>  libavcodec/vvc/thread.c | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/libavcodec/vvc/refs.c b/libavcodec/vvc/refs.c
> index 8b7ba639a3..26a5b0b34c 100644
> --- a/libavcodec/vvc/refs.c
> +++ b/libavcodec/vvc/refs.c
> @@ -191,7 +191,7 @@ int ff_vvc_set_new_ref(VVCContext *s, VVCFrameContext
> *fc, AVFrame **frame)
>      fc->ref = ref;
>
>      if (s->no_output_before_recovery_flag && (IS_RASL(s) ||
> !GDR_IS_RECOVERED(s)))
> -        ref->flags = 0;
> +        ref->flags = VVC_FRAME_FLAG_SHORT_REF;
>      else if (ph->r->ph_pic_output_flag)
>          ref->flags = VVC_FRAME_FLAG_OUTPUT;
>
> diff --git a/libavcodec/vvc/thread.c b/libavcodec/vvc/thread.c
> index 5b01dd2d20..e87ed5b676 100644
> --- a/libavcodec/vvc/thread.c
> +++ b/libavcodec/vvc/thread.c
> @@ -801,6 +801,8 @@ int ff_vvc_frame_wait(VVCContext *s, VVCFrameContext
> *fc)
>  {
>      VVCFrameThread *ft = fc->ft;
>
> +    av_assert0(fc->ref->progress);
> +
>
Hi Frank,
Thank you for the patch.

We have a mission to remove all assert0s in the decoder, right? :)
If it's only for debugging, maybe we don't need it.

>      ff_mutex_lock(&ft->lock);
>
>      while (atomic_load(&ft->nb_scheduled_tasks) ||
> atomic_load(&ft->nb_scheduled_listeners))
> --
> 2.45.1
>
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