+ int const r = avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet);
+ if (r >= 0 && frame_finished) {
+
+ if (r != _packet.size) {
+ _film->log()->log (String::compose ("Used only %1 bytes of %2 in packet", r, _packet.size));
+ }
+
+ /* Where we are in the output, in seconds */
+ double const out_pts_seconds = video_frame() / frames_per_second();
+
+ /* Where we are in the source, in seconds */
+ double const source_pts_seconds = av_q2d (_format_context->streams[_packet.stream_index]->time_base)
+ * av_frame_get_best_effort_timestamp(_frame);
+
+ _film->log()->log (
+ String::compose ("Source video frame ready; source at %1, output at %2", source_pts_seconds, out_pts_seconds),
+ Log::VERBOSE
+ );
+
+ if (!_first_video) {
+ _first_video = source_pts_seconds;
+ }
+
+ /* Difference between where we are and where we should be */
+ double const delta = source_pts_seconds - _first_video.get() - out_pts_seconds;
+ double const one_frame = 1 / frames_per_second();
+
+ /* 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) {
+ repeat_last_video ();
+ _film->log()->log (
+ String::compose (
+ "Extra video frame inserted at %1s; source frame %2, source PTS %3 (at %4 fps)",
+ out_pts_seconds, video_frame(), source_pts_seconds, frames_per_second()
+ )
+ );
+ }
+ }
+
+ if (delta > -one_frame) {
+ /* Process this frame */
+ filter_and_emit_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));
+ }