Try to improve refetching of last frame and seek backwards.

diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index 27009114c3e34492046ae4ec497018fd3287c9a3..c77cb71c0ac9ca465415f17b43556c720e6c16f2 100644 (file)
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -264,8 +264,22 @@ void
 FFmpegDecoder::seek (VideoContent::Frame frame, bool accurate)
 {
        double const time_base = av_q2d (_format_context->streams[_video_stream]->time_base);
-       int64_t const vt = frame / (_ffmpeg_content->video_frame_rate() * time_base);
-       av_seek_frame (_format_context, _video_stream, vt, AVSEEK_FLAG_BACKWARD);
+
+       /* If we are doing an accurate seek, our initial shot will be 5 frames (5 being
+          a number plucked from the air) earlier than we want to end up.  The loop below
+          will hopefully then step through to where we want to be.
+       */
+       int initial = frame;
+       if (accurate) {
+               initial -= 5;
+       }
+
+       /* Initial seek time in the stream's timebase */
+       int64_t const initial_vt = initial / (_ffmpeg_content->video_frame_rate() * time_base);
+       /* Wanted final seek time in the stream's timebase */
+       int64_t const final_vt = frame / (_ffmpeg_content->video_frame_rate() * time_base);
+       
+       av_seek_frame (_format_context, _video_stream, initial_vt, AVSEEK_FLAG_BACKWARD);
 
        avcodec_flush_buffers (video_codec_context());
        if (_subtitle_codec_context) {
@@ -293,7 +307,7 @@ FFmpegDecoder::seek (VideoContent::Frame frame, bool accurate)
                                int const r = avcodec_decode_video2 (video_codec_context(), _frame, &finished, &_packet);
                                if (r >= 0 && finished) {
                                        int64_t const bet = av_frame_get_best_effort_timestamp (_frame);
-                                       if (bet >= vt) {
+                                       if (bet >= final_vt) {
                                                _video_position = rint (
                                                        (bet * time_base + _pts_offset) * _ffmpeg_content->video_frame_rate()
                                                        );

diff --git a/src/wx/film_viewer.cc b/src/wx/film_viewer.cc
index 2cc63aea4da7d0e5185c010b9485fd893cadfc8c..ab53a9d154c48f21a2ae03db46890aed986f71e5 100644 (file)
--- a/src/wx/film_viewer.cc
+++ b/src/wx/film_viewer.cc
@@ -141,8 +141,12 @@ FilmViewer::fetch_current_frame_again ()
        }
 
        Time const t = _film->video_frames_to_time (1);
-       
-       _player->seek (_player->video_position() - t * 1.5, true);
+
+       /* This 2.5 is, in theory: 1 to get back to the same frame, 1 more
+          because we are about to call fetch_next_frame(), and 0.5 for luck.
+       */
+          
+       _player->seek (_player->video_position() - t * 2.5, true);
        fetch_next_frame ();
 }