Try to use the previous frame rather than the current one when padding PTS gaps.

diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index 023b6d540fe02134c328fc006fe5b0df535a1dd5..e9d107a8911f02d7d5f6ce67da9dcda66976a23f 100644 (file)
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -61,7 +61,9 @@ FFmpegDecoder::FFmpegDecoder (shared_ptr<Film> f, shared_ptr<const Options> o, J
        , _video_stream (-1)
        , _audio_stream (-1)
        , _subtitle_stream (-1)
-       , _frame (0)
+       , _last_video_frame (-1)
+       , _this_video_frame (0)
+       , _audio_frame (0)
        , _video_codec_context (0)
        , _video_codec (0)
        , _audio_codec_context (0)
@@ -69,6 +71,10 @@ FFmpegDecoder::FFmpegDecoder (shared_ptr<Film> f, shared_ptr<const Options> o, J
        , _subtitle_codec_context (0)
        , _subtitle_codec (0)
 {
+       for (int i = 0; i < 2; ++i) {
+               _video_frame[i] = 0;
+       }
+       
        setup_general ();
        setup_video ();
        setup_audio ();
@@ -88,8 +94,13 @@ FFmpegDecoder::~FFmpegDecoder ()
        if (_subtitle_codec_context) {
                avcodec_close (_subtitle_codec_context);
        }
+
+       for (int i = 0; i < 2; ++i) {
+               av_free (_video_frame[i]);
+       }
+
+       av_free (_audio_frame);
        
-       av_free (_frame);
        avformat_close_input (&_format_context);
 }      
 
@@ -141,8 +152,15 @@ FFmpegDecoder::setup_general ()
                throw DecodeError ("could not find video stream");
        }
 
-       _frame = avcodec_alloc_frame ();
-       if (_frame == 0) {
+       for (int i = 0; i < 2; ++i) {
+               _video_frame[i] = avcodec_alloc_frame ();
+               if (_video_frame[i] == 0) {
+                       throw DecodeError ("could not allocate frame");
+               }
+       }
+
+       _audio_frame = avcodec_alloc_frame ();
+       if (_audio_frame == 0) {
                throw DecodeError ("could not allocate frame");
        }
 }
@@ -235,18 +253,18 @@ FFmpegDecoder::do_pass ()
 
                int frame_finished;
 
-               while (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
-                       process_video (_frame);
+               while (avcodec_decode_video2 (_video_codec_context, _video_frame[_this_video_frame], &frame_finished, &_packet) >= 0 && frame_finished) {
+                       process_video (_video_frame[_this_video_frame]);
                }
 
                if (_audio_stream >= 0 && _opt->decode_audio) {
-                       while (avcodec_decode_audio4 (_audio_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
+                       while (avcodec_decode_audio4 (_audio_codec_context, _audio_frame, &frame_finished, &_packet) >= 0 && frame_finished) {
                                int const data_size = av_samples_get_buffer_size (
-                                       0, _audio_codec_context->channels, _frame->nb_samples, audio_sample_format (), 1
+                                       0, _audio_codec_context->channels, _audio_frame->nb_samples, audio_sample_format (), 1
                                        );
 
                                assert (_audio_codec_context->channels == _film->audio_channels());
-                               process_audio (_frame->data[0], data_size);
+                               process_audio (_audio_frame->data[0], data_size);
                        }
                }
 
@@ -255,16 +273,16 @@ FFmpegDecoder::do_pass ()
 
        double const pts_seconds = av_q2d (_format_context->streams[_packet.stream_index]->time_base) * _packet.pts;
 
-       avcodec_get_frame_defaults (_frame);
-       
        if (_packet.stream_index == _video_stream) {
 
+               avcodec_get_frame_defaults (_video_frame[_this_video_frame]);
+               
                if (!_first_video) {
                        _first_video = pts_seconds;
                }
 
                int frame_finished;
-               if (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
+               if (avcodec_decode_video2 (_video_codec_context, _video_frame[_this_video_frame], &frame_finished, &_packet) >= 0 && frame_finished) {
 
                        /* Where we are in the output, in seconds */
                        double const out_pts_seconds = video_frame() / frames_per_second();
@@ -273,22 +291,29 @@ FFmpegDecoder::do_pass ()
                        double const delta = pts_seconds - out_pts_seconds;
                        double const one_frame = 1 / frames_per_second();
 
+                       /* Insert the last frame if we have one, otherwise just use this one */
+                       int const insert_frame = _last_video_frame == -1 ? _this_video_frame : _last_video_frame;
+
                        /* Insert frames if required to get out_pts_seconds up to pts_seconds */
                        if (delta > one_frame) {
                                int const extra = rint (delta / one_frame);
                                for (int i = 0; i < extra; ++i) {
                                        _film->log()->log (String::compose ("Extra frame inserted at %1s", out_pts_seconds));
-                                       process_video (_frame);
+                                       process_video (_video_frame[insert_frame]);
                                }
                        }
 
                        if (delta > -one_frame) {
                                /* Process this frame */
-                               process_video (_frame);
+                               process_video (_video_frame[_this_video_frame]);
                        } else {
                                /* Otherwise we are omitting a frame to keep things right */
                                _film->log()->log (String::compose ("Frame removed at %1s", out_pts_seconds));
                        }
+
+                       /* Swap over so that we use the alternate video frames next time */
+                       _this_video_frame = 1 - _this_video_frame;
+                       _last_video_frame = 1 - _this_video_frame;
                }
 
        } else if (_audio_stream >= 0 && _packet.stream_index == _audio_stream && _opt->decode_audio && _first_video && _first_video.get() <= pts_seconds) {
@@ -327,13 +352,13 @@ FFmpegDecoder::do_pass ()
                }
                
                int frame_finished;
-               if (avcodec_decode_audio4 (_audio_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
+               if (avcodec_decode_audio4 (_audio_codec_context, _audio_frame, &frame_finished, &_packet) >= 0 && frame_finished) {
                        int const data_size = av_samples_get_buffer_size (
-                               0, _audio_codec_context->channels, _frame->nb_samples, audio_sample_format (), 1
+                               0, _audio_codec_context->channels, _audio_frame->nb_samples, audio_sample_format (), 1
                                );
                        
                        assert (_audio_codec_context->channels == _film->audio_channels());
-                       process_audio (_frame->data[0], data_size);
+                       process_audio (_audio_frame->data[0], data_size);
                }
                        
        } else if (_subtitle_stream >= 0 && _packet.stream_index == _subtitle_stream && _opt->decode_subtitles && _first_video) {

diff --git a/src/lib/ffmpeg_decoder.h b/src/lib/ffmpeg_decoder.h
index abcdfa0b2cd32ee4408563ad5e8cfe5504b8c072..58e08a7797a005eeaefab25e8fa5553ee6c15bf2 100644 (file)
--- a/src/lib/ffmpeg_decoder.h
+++ b/src/lib/ffmpeg_decoder.h
@@ -89,7 +89,11 @@ private:
        int _video_stream;
        int _audio_stream; ///< may be < 0 if there is no audio
        int _subtitle_stream; ///< may be < 0 if there is no subtitle
-       AVFrame* _frame;
+       
+       AVFrame* _video_frame[2];
+       int _last_video_frame;
+       int _this_video_frame;
+       AVFrame* _audio_frame;
 
        std::vector<AudioStream> _audio_streams;
        std::vector<SubtitleStream> _subtitle_streams;