[FFmpeg-devel] [PATCH] avfilter/src_movie: dr support
James Almer
jamrial at gmail.com
Tue May 16 00:45:08 EEST 2023
> From 6fddad6ea2abf91a7378fb367a439441ef8f32b4 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 2/3] avfilter/src_movie: dr support
>
> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> ---
> libavfilter/src_movie.c | 32 ++++++++++++++++++++++++++++++--
> 1 file changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/libavfilter/src_movie.c b/libavfilter/src_movie.c
> index a7d7c188e6..0629030f91 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
> */
>
> @@ -158,6 +157,31 @@ static AVStream *find_stream(void *log, AVFormatContext *avf, const char *spec)
> return found;
> }
>
> +static int get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
> +{
> + AVFrame *new;
> +
> + if (flags & AV_GET_BUFFER_FLAG_REF)
> + return avcodec_default_get_buffer2(avctx, frame, flags);
Why? The frames returned by ff_get_{audio,video}_buffer() are refcounted
and writable.
You should however use avcodec_default_get_buffer2() for non
AV_CODEC_CAP_DR1 decoders. Also, you need to use
avcodec_align_dimensions2() to get the correct dimensions.
> +
> + switch (avctx->codec_type) {
> + case AVMEDIA_TYPE_VIDEO:
> + new = ff_get_video_buffer(frame->opaque, frame->width, frame->height);
> + break;
> + case AVMEDIA_TYPE_AUDIO:
> + new = ff_get_audio_buffer(frame->opaque, frame->nb_samples);
> + break;
> + default:
> + return -1;
> + }
> +
> + av_frame_unref(frame);
The documentation for get_buffer2() says:
> * The following fields will be set in the frame before this callback is
> * called:
> * - format
> * - width, height (video only)
> * - sample_rate, channel_layout, nb_samples (audio only)
> * Their values may differ from the corresponding values in
> * AVCodecContext. This callback must use the frame values, not the codec
> * context values, to calculate the required buffer size.
So you're not really supposed to touch anything else than data, buf,
extended_data, extended_buf, and linesize, which an unref call will do.
But as long as the necessary values in the AVFilterLink match those in
the frame, i guess it should be ok.
> + av_frame_move_ref(frame, new);
> + av_frame_free(&new);
> +
> + return 0;
> +}
> +
> static int open_stream(AVFilterContext *ctx, MovieStream *st, int dec_threads)
> {
> const AVCodec *codec;
> @@ -173,6 +197,8 @@ 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;
> @@ -480,8 +506,10 @@ 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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