[FFmpeg-devel] [PATCH 4/4] avcodec/h264dec: apply H.274 film grain

[Michael Niedermayer]

On Sat, Aug 14, 2021 at 01:36:20PM +0200, Niklas Haas wrote:
> From: Niklas Haas <git at haasn.dev>
> 
> Because we need access to ref frames without film grain applied, we have
> to add an extra AVFrame to H264Picture to avoid messing with the
> original. This requires some amount of overhead to make the reference
> moves work out, but it allows us to benefit from frame multithreading
> for film grain application "for free".
> 
> Unfortunately, this approach requires twice as much RAM to be constantly
> allocated, due to the need for an extra buffer per H264Picture. In
> theory, we could get away with freeing up this memory as soon as it's no
> longer needed, but trying to call ff_thread_release_buffer() from
> output_frame() simply deadlocks the decoder and I haven't figured out
> why. Patches welcome(tm)
> 
> Tested on all three cases of (no fg), (fg present but exported) and (fg
> present and not exported), with and without threading.
> ---
>  libavcodec/h264_picture.c | 24 +++++++++++++++++++-
>  libavcodec/h264_slice.c   | 18 +++++++++++++--
>  libavcodec/h264dec.c      | 48 +++++++++++++++++++++++++++++++--------
>  libavcodec/h264dec.h      |  6 +++++
>  4 files changed, 83 insertions(+), 13 deletions(-)

[...]
> @@ -826,6 +836,21 @@ static int output_frame(H264Context *h, AVFrame *dst, H264Picture *srcp)
>      AVFrame *src = srcp->f;
>      int ret;
>  
> +    if (srcp->needs_fg) {

> +        AVFrameSideData *sd = av_frame_get_side_data(src, AV_FRAME_DATA_FILM_GRAIN_PARAMS);
> +        av_assert0(sd);

Assertion is not correct to check for failure

This would kill the process with the lib and app


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

While the State exists there can be no freedom; when there is freedom there
will be no State. -- Vladimir Lenin
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 195 bytes
Desc: not available
URL: <https://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20210815/4ec2494f/attachment.sig>