- if (!_first_video) {
- _first_video = pts_seconds;
- }
-
- int frame_finished;
- if (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
- process_video (_frame);
- }
-
- } else if (_audio_stream >= 0 && _packet.stream_index == _audio_stream && _opt->decode_audio && _first_video && _first_video.get() <= pts_seconds) {
-
- /* Note: We only decode audio if we've had our first video packet through, and if it
- was before this packet. Until then audio is thrown away.
- */
-
- if (!_first_audio) {
- _first_audio = pts_seconds;
-
- /* This is our first audio packet, and if we've arrived here we must have had our
- first video packet. Push some silence to make up the gap between our first
- video packet and our first audio.
- */
-
- /* frames of silence that we must push */
- int const s = rint ((_first_audio.get() - _first_video.get()) * audio_sample_rate ());
-
- _log->log (
- String::compose (
- "First video at %1, first audio at %2, pushing %3 frames of silence for %4 channels (%5 bytes per sample)",
- _first_video.get(), _first_audio.get(), s, audio_channels(), bytes_per_audio_sample()
- )
- );
-
- /* hence bytes */
- int const b = s * audio_channels() * bytes_per_audio_sample();
-
- /* XXX: this assumes that it won't be too much, and there are shaky assumptions
- that all sound representations are silent with memset()ed zero data.
- */
- uint8_t silence[b];
- memset (silence, 0, b);
- process_audio (silence, b);
- }
-
- avcodec_get_frame_defaults (_frame);
-
- int frame_finished;
- if (avcodec_decode_audio4 (_audio_codec_context, _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
- );
-
- assert (_audio_codec_context->channels == _film->audio_channels());
- process_audio (_frame->data[0], data_size);
- }
-
- } else if (_subtitle_stream >= 0 && _packet.stream_index == _subtitle_stream && _opt->decode_subtitles && _first_video) {