Repeating ffmpeg stream (libavcodec/libavformat) - c++

Question

I am using the various APIs from ffmpeg to draw videos in my application. So far this works very well. Since I also have gifs I want to do looping without having to load the file over and over again.
In my code the decoder loop looks like this:
AVPacket packet = {};
av_init_packet(&packet);
while (mIsRunning) {
int error = av_read_frame(mContext, &packet);
if (error == AVERROR_EOF) {
if(mRepeat) {
logger.info("EOF-repeat");
auto stream = mContext->streams[mVideoStream];
av_seek_frame(mContext, mVideoStream, 0, 0);
continue;
}
if (mReadVideo) {
avcodec_send_packet(mVideoCodec, nullptr);
}
if (mReadAudio) {
avcodec_send_packet(mAudioCodec, nullptr);
}
break;
}
if (error < 0) {
char err[AV_ERROR_MAX_STRING_SIZE];
av_make_error_string(err, AV_ERROR_MAX_STRING_SIZE, error);
logger.error("Failed to read next frame from stream: ", err);
throw std::runtime_error("Stream reading failed");
}
if (packet.stream_index == mVideoStream && mReadVideo) {
int32 err;
{
std::lock_guard<std::mutex> l(mVideoLock);
err = avcodec_send_packet(mVideoCodec, &packet);
}
mImageEvent.notify_all();
while (err == AVERROR(EAGAIN) && mIsRunning) {
{
std::unique_lock<std::mutex> l(mReaderLock);
mReaderEvent.wait(l);
}
{
std::lock_guard<std::mutex> l(mVideoLock);
err = avcodec_send_packet(mVideoCodec, &packet);
}
}
}
av_packet_unref(&packet);
}
Reading a video to the end works perfectly well and if I dont set mRepeat to true it properly EOFs and stops parsing. However when I use looping the following happens:
The video ends
AVERROR_EOF happens at av_read_frame
EOF-repeat is printed
A random frame is read from the stream (and rendered)
AVERROR_EOF happens at av_read_frame
EOF-repeat is printed
A random frame is read from the stream (and rendered)
...
You can imagine it like I have a gif of a spinning globe and after one full turn it just starts randomly jumping around, sometimes for a fraction of a second correctly, sometimes backwards and sometimes just randomly everywhere.
I have also tried several versions with avformat_seek_file what other way would there be to reset everything to the beginning and start from scratch again?

Answer 1

I figured out that I also need to reset my IO context to the beginning:
if(mRepeat) {
auto stream = mContext->streams[mVideoStream];
avio_seek(mContext->pb, 0, SEEK_SET);
avformat_seek_file(mContext, mVideoStream, 0, 0, stream->duration, 0);
continue;
}
Now the video properly loops forever :)