[FFmpeg-devel] [PATCH] lavf/utils: Fix DTS for short H264 streams.

[Sasi Inguva]

Having another go at this. My goal is to fix DTS of H264 videos which are
shorter than 7 frames and don't have B-frames. Currently ffmpeg will output
DTS=N/A for such frames.

On Fri, Mar 11, 2016 at 12:34 PM, Sasi Inguva <isasi at google.com> wrote:

> Fill DTS if all packets have been read in avformat_find_stream_info, and
> still
> has_decode_delay_been_guessed returns false.
>
> Signed-off-by: Sasi Inguva <isasi at google.com>
> ---
>  libavformat/utils.c | 37 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
>
> diff --git a/libavformat/utils.c b/libavformat/utils.c
> index 5f48de1..f22309d 100644
> --- a/libavformat/utils.c
> +++ b/libavformat/utils.c
> @@ -877,6 +877,7 @@ static int has_decode_delay_been_guessed(AVStream *st)
>         avpriv_h264_has_num_reorder_frames(st->codec) ==
> st->codec->has_b_frames)
>          return 1;
>  #endif
> +
>      if (st->codec->has_b_frames<3)
>          return st->nb_decoded_frames >= 7;
>      else if (st->codec->has_b_frames<4)
> @@ -3165,6 +3166,7 @@ int avformat_find_stream_info(AVFormatContext *ic,
> AVDictionary **options)
>      int64_t max_stream_analyze_duration;
>      int64_t max_subtitle_analyze_duration;
>      int64_t probesize = ic->probesize;
> +    int eof_reached = 0;
>
>      flush_codecs = probesize > 0;
>
> @@ -3331,6 +3333,7 @@ int avformat_find_stream_info(AVFormatContext *ic,
> AVDictionary **options)
>
>          if (ret < 0) {
>              /* EOF or error*/
> +            eof_reached = 1;
>              break;
>          }
>
> @@ -3454,6 +3457,40 @@ int avformat_find_stream_info(AVFormatContext *ic,
> AVDictionary **options)
>          count++;
>      }
>
> +    if (eof_reached && ic->internal->packet_buffer) {
> +        int stream_index;
> +        for (stream_index = 0; stream_index < ic->nb_streams;
> stream_index++) {
> +            AVPacketList *pktl = ic->internal->packet_buffer;
> +            int64_t pts_buffer[MAX_REORDER_DELAY+1];
> +
> +            // EOF already reached while reading the stream above.
> +            // So continue with reoordering DTS with whatever delay we
> have.
> +            int codec_delay = st->codec->has_b_frames;
> +
> +            st = ic->streams[stream_index];
> +
> +            if (st->codec->codec_id != AV_CODEC_ID_H264 ||
> +                has_decode_delay_been_guessed(st)) {
> +                continue;
> +            }
> +
> +
> +            for (; pktl; pktl = get_next_pkt(ic, st, pktl)) {
> +                if (pktl->pkt.stream_index != stream_index)
> +                    continue;
> +
> +                if (pktl->pkt.pts != AV_NOPTS_VALUE && codec_delay <=
> MAX_REORDER_DELAY) {
> +                    int j;
> +                    pts_buffer[0] = pktl->pkt.pts;
> +                    for (j = 0; j < codec_delay && pts_buffer[j] >
> pts_buffer[j + 1]; j++)
> +                      FFSWAP(int64_t, pts_buffer[j], pts_buffer[j + 1]);
> +
> +                    pktl->pkt.dts = select_from_pts_buffer(st,
> pts_buffer, pktl->pkt.dts);
> +                }
> +            }
> +        }
> +    }
> +
>      if (flush_codecs) {
>          AVPacket empty_pkt = { 0 };
>          int err = 0;
> --
> 2.7.0.rc3.207.g0ac5344
>
>