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

[Paul B Mahol <onemda@gmail.com>]

On Fri, May 19, 2023 at 9:52 AM Paul B Mahol <onemda@gmail.com> wrote:

>
>
> On Thu, May 18, 2023 at 8:01 PM James Almer <jamrial@gmail.com> wrote:
>
>> On 5/18/2023 2:44 PM, Paul B Mahol wrote:
>> > On Thu, May 18, 2023 at 7:31 PM James Almer <jamrial@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@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@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.
>>
>>
> I tried that, and also own .h264 file hash decoding is always same.
> tsan shows warnings for both without and with this filter and frame
> threading.
>

Only issue I found is if you use tmix filter after: ffmpeg -f lavfi -i
movie=resolution_change_name.file,tmix
It will produce invalid output with MD5 hash different each time, same as
with threads=1
But exact same issue is without this 2 patches, and present in current
version of FFmpeg.

Nice workaround is just inserting scale filter between movie and tmix.


>
>> >
>> >
>> >>
>> >>> +        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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