[FFmpeg-devel] [PATCH] avfilter/src_movie: activate & dr

[James Almer]

On 5/18/2023 2:44 PM, Paul B Mahol wrote:
> On Thu, May 18, 2023 at 7:31 PM James Almer <jamrial at gmail.com> wrote:
> 
>> On 5/18/2023 7:22 AM, Paul B Mahol wrote:
>>>  From af73b69a0be9033fddf222b6e9ac60799de85691 Mon Sep 17 00:00:00 2001
>>> From: Paul B Mahol <onemda at gmail.com>
>>> Date: Mon, 15 May 2023 21:54:25 +0200
>>> Subject: [PATCH 26/27] avfilter/src_movie: dr support
>>>
>>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
>>> ---
>>>   libavfilter/src_movie.c | 44 +++++++++++++++++++++++++++++++++++++++--
>>>   1 file changed, 42 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/libavfilter/src_movie.c b/libavfilter/src_movie.c
>>> index 5937613d13..a2ecc5a625 100644
>>> --- a/libavfilter/src_movie.c
>>> +++ b/libavfilter/src_movie.c
>>> @@ -23,7 +23,6 @@
>>>    * @file
>>>    * movie video source
>>>    *
>>> - * @todo use direct rendering (no allocation of a new frame)
>>>    * @todo support a PTS correction mechanism
>>>    */
>>>
>>> @@ -156,6 +155,43 @@ static AVStream *find_stream(void *log,
>> AVFormatContext *avf, const char *spec)
>>>       return found;
>>>   }
>>>
>>> +static int get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
>>> +{
>>> +    int linesize_align[AV_NUM_DATA_POINTERS];
>>> +    AVFilterLink *outlink = frame->opaque;
>>> +    int w, h, ow, oh;
>>> +    AVFrame *new;
>>> +
>>> +    h = oh = frame->height;
>>> +    w = ow = frame->width;
>>> +
>>> +    if (!(avctx->codec->capabilities & AV_CODEC_CAP_DR1))
>>> +        return avcodec_default_get_buffer2(avctx, frame, flags);
>>> +
>>> +    switch (avctx->codec_type) {
>>> +    case AVMEDIA_TYPE_VIDEO:
>>> +        avcodec_align_dimensions2(avctx, &w, &h, linesize_align);
>>> +        new = ff_default_get_video_buffer(outlink, w, h);
>>> +        break;
>>> +    case AVMEDIA_TYPE_AUDIO:
>>> +        new = ff_default_get_audio_buffer(outlink, frame->nb_samples);
>>
>> I wonder, are these two functions thread safe?
>> AVCodecContext.get_buffer2() no longer supports non-thread safe
>> callbacks, and these seem to allocate and replace the pool inside
>> outlink as required. If called from more than one thread with different
>> frame parameters, wouldn't there be a race?
>>
> 
> I encountered no issues in my testing.

Try a sample that changes dimensions every other frame, like 
vp9-test-vectors/vp90-2-05-resize.ivf, and make sure to set filter 
threads so it's propagated to the src_movie internal decoder, to some 
value like 4 or higher. Run it under tsan.

> 
> 
>>
>>> +        break;
>>> +    default:
>>> +        return -1;
>>> +    }
>>> +
>>> +    av_frame_copy_props(new, frame);
>>> +    av_frame_unref(frame);
>>> +    av_frame_move_ref(frame, new);
>>> +    av_frame_free(&new);
>>> +
>>> +    frame->opaque = outlink;
>>> +    frame->width  = ow;
>>> +    frame->height = oh;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>>   static int open_stream(AVFilterContext *ctx, MovieStream *st, int
>> dec_threads)
>>>   {
>>>       const AVCodec *codec;
>>> @@ -171,6 +207,8 @@ static int open_stream(AVFilterContext *ctx,
>> MovieStream *st, int dec_threads)
>>>       if (!st->codec_ctx)
>>>           return AVERROR(ENOMEM);
>>>
>>> +    st->codec_ctx->flags |= AV_CODEC_FLAG_COPY_OPAQUE;
>>> +    st->codec_ctx->get_buffer2 = get_buffer;
>>>       ret = avcodec_parameters_to_context(st->codec_ctx,
>> st->st->codecpar);
>>>       if (ret < 0)
>>>           return ret;
>>> @@ -479,8 +517,10 @@ static int movie_decode_packet(AVFilterContext *ctx)
>>>       /* send the packet to its decoder, if any */
>>>       pkt_out_id = pkt.stream_index > movie->max_stream_index ? -1 :
>>>                    movie->out_index[pkt.stream_index];
>>> -    if (pkt_out_id >= 0)
>>> +    if (pkt_out_id >= 0) {
>>> +        pkt.opaque = ctx->outputs[pkt_out_id];
>>>           ret = avcodec_send_packet(movie->st[pkt_out_id].codec_ctx,
>> &pkt);
>>> +    }
>>>       av_packet_unref(&pkt);
>>>
>>>       return ret;
>>> --
>>> 2.39.1
>>>
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