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Fix invalid starting PTS value, preventing blank 1st frames on some t…
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…humbnailing and video players.
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@jonoomph
jonoomph committed Jun 25, 2021
1 parent 09eb807 commit bdf6e9f
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Showing 2 changed files with 56 additions and 55 deletions.
109 changes: 55 additions & 54 deletions src/FFmpegWriter.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,10 @@ FFmpegWriter::FFmpegWriter(const std::string& path) :
info.has_audio = false;
info.has_video = false;

// Init timestamps
write_video_count = 0;
write_audio_count = 0;

// Initialize FFMpeg, and register all formats and codecs
AV_REGISTER_ALL

Expand Down Expand Up @@ -910,60 +914,63 @@ void FFmpegWriter::flush_encoders() {
}

// FLUSH AUDIO ENCODER
if (info.has_audio)
for (;;) {

// Increment PTS (in samples and scaled to the codec's timebase)
// for some reason, it requires me to multiply channels X 2
write_audio_count += av_rescale_q(audio_input_position / (audio_codec_ctx->channels * av_get_bytes_per_sample(AV_SAMPLE_FMT_S16)), av_make_q(1, info.sample_rate), audio_codec_ctx->time_base);

AVPacket pkt;
av_init_packet(&pkt);
pkt.data = NULL;
pkt.size = 0;
pkt.pts = pkt.dts = write_audio_count;
if (info.has_audio) {
for (;;) {
AVPacket pkt;
av_init_packet(&pkt);
pkt.data = NULL;
pkt.size = 0;
pkt.pts = pkt.dts = write_audio_count;

/* encode the image */
int error_code = 0;
int got_packet = 0;
/* encode the image */
int error_code = 0;
int got_packet = 0;
#if IS_FFMPEG_3_2
error_code = avcodec_send_frame(audio_codec_ctx, NULL);
error_code = avcodec_send_frame(audio_codec_ctx, NULL);
#else
error_code = avcodec_encode_audio2(audio_codec_ctx, &pkt, NULL, &got_packet);
error_code = avcodec_encode_audio2(audio_codec_ctx, &pkt, NULL, &got_packet);
#endif
if (error_code < 0) {
ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::flush_encoders ERROR [" + (std::string)av_err2str(error_code) + "]", "error_code", error_code);
}
if (!got_packet) {
break;
}
if (error_code < 0) {
ZmqLogger::Instance()->AppendDebugMethod(
"FFmpegWriter::flush_encoders ERROR [" + (std::string) av_err2str(error_code) + "]",
"error_code", error_code);
}
if (!got_packet) {
break;
}

// Since the PTS can change during encoding, set the value again. This seems like a huge hack,
// but it fixes lots of PTS related issues when I do this.
pkt.pts = pkt.dts = write_audio_count;
// Since the PTS can change during encoding, set the value again. This seems like a huge hack,
// but it fixes lots of PTS related issues when I do this.
pkt.pts = pkt.dts = write_audio_count;

// Scale the PTS to the audio stream timebase (which is sometimes different than the codec's timebase)
if (pkt.pts != AV_NOPTS_VALUE)
pkt.pts = av_rescale_q(pkt.pts, audio_codec_ctx->time_base, audio_st->time_base);
if (pkt.dts != AV_NOPTS_VALUE)
pkt.dts = av_rescale_q(pkt.dts, audio_codec_ctx->time_base, audio_st->time_base);
if (pkt.duration > 0)
pkt.duration = av_rescale_q(pkt.duration, audio_codec_ctx->time_base, audio_st->time_base);
// Scale the PTS to the audio stream timebase (which is sometimes different than the codec's timebase)
if (pkt.pts != AV_NOPTS_VALUE)
pkt.pts = av_rescale_q(pkt.pts, audio_codec_ctx->time_base, audio_st->time_base);
if (pkt.dts != AV_NOPTS_VALUE)
pkt.dts = av_rescale_q(pkt.dts, audio_codec_ctx->time_base, audio_st->time_base);
if (pkt.duration > 0)
pkt.duration = av_rescale_q(pkt.duration, audio_codec_ctx->time_base, audio_st->time_base);

// set stream
pkt.stream_index = audio_st->index;
pkt.flags |= AV_PKT_FLAG_KEY;
// set stream
pkt.stream_index = audio_st->index;
pkt.flags |= AV_PKT_FLAG_KEY;

// Write packet
error_code = av_interleaved_write_frame(oc, &pkt);
if (error_code < 0) {
ZmqLogger::Instance()->AppendDebugMethod("FFmpegWriter::flush_encoders ERROR [" + (std::string)av_err2str(error_code) + "]", "error_code", error_code);
}
// Write packet
error_code = av_interleaved_write_frame(oc, &pkt);
if (error_code < 0) {
ZmqLogger::Instance()->AppendDebugMethod(
"FFmpegWriter::flush_encoders ERROR [" + (std::string) av_err2str(error_code) + "]",
"error_code", error_code);
}

// deallocate memory for packet
AV_FREE_PACKET(&pkt);
}
// deallocate memory for packet
AV_FREE_PACKET(&pkt);
}

// Increment PTS (in samples and scaled to the codec's timebase)
// for some reason, it requires me to multiply channels X 2
write_audio_count += av_rescale_q(audio_input_position / (audio_codec_ctx->channels * av_get_bytes_per_sample(AV_SAMPLE_FMT_S16)), av_make_q(1, info.sample_rate), audio_codec_ctx->time_base);
}

}

Expand Down Expand Up @@ -2042,8 +2049,7 @@ bool FFmpegWriter::write_video_packet(std::shared_ptr<Frame> frame, AVFrame *fra
pkt.data = (uint8_t *) frame_final->data;
pkt.size = sizeof(AVPicture);

// Increment PTS (in frames and scaled to the codec's timebase)
write_video_count += av_rescale_q(1, av_make_q(info.fps.den, info.fps.num), video_codec_ctx->time_base);
// Set PTS (in frames and scaled to the codec's timebase)
pkt.pts = write_video_count;

/* write the compressed frame in the media file */
Expand All @@ -2065,9 +2071,6 @@ bool FFmpegWriter::write_video_packet(std::shared_ptr<Frame> frame, AVFrame *fra
pkt.size = 0;
pkt.pts = pkt.dts = AV_NOPTS_VALUE;

// Increment PTS (in frames and scaled to the codec's timebase)
write_video_count += av_rescale_q(1, av_make_q(info.fps.den, info.fps.num), video_codec_ctx->time_base);

// Assign the initial AVFrame PTS from the frame counter
frame_final->pts = write_video_count;
#if USE_HW_ACCEL
Expand Down Expand Up @@ -2142,11 +2145,6 @@ bool FFmpegWriter::write_video_packet(std::shared_ptr<Frame> frame, AVFrame *fra

/* if zero size, it means the image was buffered */
if (error_code == 0 && got_packet_ptr) {

// Since the PTS can change during encoding, set the value again. This seems like a huge hack,
// but it fixes lots of PTS related issues when I do this.
//pkt.pts = pkt.dts = write_video_count;

// set the timestamp
if (pkt.pts != AV_NOPTS_VALUE)
pkt.pts = av_rescale_q(pkt.pts, video_codec_ctx->time_base, video_st->time_base);
Expand Down Expand Up @@ -2176,6 +2174,9 @@ bool FFmpegWriter::write_video_packet(std::shared_ptr<Frame> frame, AVFrame *fra
#endif // USE_HW_ACCEL
}

// Increment PTS (in frames and scaled to the codec's timebase)
write_video_count += av_rescale_q(1, av_make_q(info.fps.den, info.fps.num), video_codec_ctx->time_base);

// Success
return true;
}
Expand Down
2 changes: 1 addition & 1 deletion src/QtPlayer.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -119,7 +119,7 @@ namespace openshot

void QtPlayer::Play()
{
// Set mode to playing, and speed to normal
// Set mode to playing, and speed to normal
mode = PLAYBACK_PLAY;
Speed(1);

Expand Down

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