[FFmpeg-devel] [PATCH] doc/examples/filtering_video: switch to new decoding API

[wm4]

On Wed, 29 Mar 2017 15:03:55 +0200
Matthieu Bouron <matthieu.bouron at gmail.com> wrote:

> ---
>  doc/examples/filtering_video.c | 32 ++++++++++++++++++++++++++------
>  1 file changed, 26 insertions(+), 6 deletions(-)
> 
> diff --git a/doc/examples/filtering_video.c b/doc/examples/filtering_video.c
> index 15116d3881..b664c69f9d 100644
> --- a/doc/examples/filtering_video.c
> +++ b/doc/examples/filtering_video.c
> @@ -211,6 +211,7 @@ int main(int argc, char **argv)
>  {
>      int ret;
>      AVPacket packet;
> +    int keep_packet = 0;
>      AVFrame *frame = av_frame_alloc();
>      AVFrame *filt_frame = av_frame_alloc();
>      int got_frame;
> @@ -234,14 +235,30 @@ int main(int argc, char **argv)
>  
>      /* read all packets */
>      while (1) {
> -        if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
> -            break;
> +        if (!keep_packet) {
> +            if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
> +                break;
> +            keep_packet = 1;
> +        }
>  
>          if (packet.stream_index == video_stream_index) {
>              got_frame = 0;
> -            ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
> -            if (ret < 0) {
> -                av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
> +
> +            ret = avcodec_send_packet(dec_ctx, &packet);
> +            if (ret >= 0) {
> +                keep_packet = 0;
> +            } else if (ret != AVERROR(EAGAIN) && ret != AVERROR_EOF) {

If you have packets after the decoder entered the EOF state, you
probably want to discard them. Either that, or reset the decoder after
it's flushed and start over. Anyway, normally this shouldn't happen.

You could also avoid the keep_packet business by running receive_frame
in a loop after send_packet (then send_packet can never fail with
EAGAIN).

> +                av_log(NULL, AV_LOG_ERROR, "Error while sending a packet to the decoder\n");
> +                break;
> +            }
> +
> +            ret = avcodec_receive_frame(dec_ctx, frame);
> +            if (ret >= 0) {
> +                got_frame = 1;
> +            } else if (ret == AVERROR_EOF) {
> +                break;
> +            } else if (ret != AVERROR(EAGAIN)) {
> +                av_log(NULL, AV_LOG_ERROR, "Error while receiving a frame from the decoder\n");
>                  break;
>              }
>  
> @@ -266,8 +283,11 @@ int main(int argc, char **argv)
>                  }
>                  av_frame_unref(frame);
>              }
> +        } else {
> +            keep_packet = 0;
>          }
> -        av_packet_unref(&packet);
> +        if (!keep_packet)
> +           av_packet_unref(&packet);
>      }
>  end:
>      avfilter_graph_free(&filter_graph);

Otherwise should work.