On 9/16/2020 9:08 PM, Andreas Rheinhardt wrote:
> Up until now, the AV1 decoder always checks before calling its wrapper
> around ff_thread_release_buffer() whether the ThreadFrame was used at
> all, i.e. it checked whether the first data buffer of the AVFrame
> contained therein is NULL or not. Yet this presumes that the AVFrame has
> been successfully allocated, even though this can of course fail; and if
> it did, one would encounter a segfault.
> Fix this by removing the checks altogether: ff_thread_release_buffer()
> can handle both unallocated as well as empty frames (since commit
> f6774f905fb3cfdc319523ac640be30b14c1bc55).
>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com>
> ---
> Removing the checks is based upon a suggestion by James Almer. I have
> not removed the checks from the other callers of av1_frame_unref() as I
> don't know how probable it is for the frame to be empty at this point.
> I tested this as well as I can, but I have no hardware with AV1 hardware
> acceleration.
You can remove the check that aborts when no hwaccel is present, which
lets get_format() successfully return a software pixel format. This will
make the decoder "work", simply outputting zeroed buffers into frames,
which is enough to test behavior like the above.
>
> libavcodec/av1dec.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/libavcodec/av1dec.c b/libavcodec/av1dec.c
> index bd8acdaafe..871db76b4d 100644
> --- a/libavcodec/av1dec.c
> +++ b/libavcodec/av1dec.c
> @@ -388,12 +388,10 @@ static av_cold int av1_decode_free(AVCodecContext
> *avctx)
> AV1DecContext *s = avctx->priv_data;
>
> for (int i = 0; i < FF_ARRAY_ELEMS(s->ref); i++) {
> - if (s->ref[i].tf.f->buf[0])
> - av1_frame_unref(avctx, &s->ref[i]);
> + av1_frame_unref(avctx, &s->ref[i]);
> av_frame_free(&s->ref[i].tf.f);
> }
> - if (s->cur_frame.tf.f->buf[0])
> - av1_frame_unref(avctx, &s->cur_frame);
> + av1_frame_unref(avctx, &s->cur_frame);
> av_frame_free(&s->cur_frame.tf.f);
>
> av_buffer_unref(&s->seq_ref);
>
LGTM.
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