Wsrtjtyk

I stream a video capture via RTP using libx264. For now, I just stream to localhost.
For watching the stream, I use the ffmpeg library. When I set the GOP size greater than 1 (only I frames), I get artefacts on the receiver side . The strange thing is, when I use ffplay, the image is perfect . What am I doing wrong?

Settings for encoding

output_codec_ctx->bit_rate = 5000000;

output_codec_ctx->width = 1920;

output_codec_ctx->height = 1080;

output_codec_ctx->time_base.den = 30; // frames per second

output_codec_ctx->time_base.num = 1;

output_codec_ctx->gop_size = 10; // gop size

output_codec_ctx->max_b_frames = 0; // B frames

output_codec_ctx->pix_fmt = AV_PIX_FMT_YUV420P; // output pixel format

output_codec_ctx->codec_type = AVMEDIA_TYPE_VIDEO;



av_opt_set(output_codec_ctx->priv_data, "preset", "ultrafast", 0);

av_opt_set(output_codec_ctx->priv_data, "tune", "zerolatency", 0);

Code for decoding

AVFormatContext *pFormatCtx;

AVCodecContext *input_codec_ctx;

AVCode *pCodec;

avdevice_register_all(); // for device

avformat_network_init();

pFormatCtx = avformat_alloc_context();

input_codec_ctx = avcodec_alloc_context3(nullptr);

AVDictionary *options = nullptr;

av_dict_set(&options, "protocol_whitelist", "file,udp,rtp", 0);

av_dict_set(&options, "fflags", "nobuffer",0);



avformat_open_input(&pFormatCtx, "rtp://127.0.0.1:49990", nullptr, &options);



avformat_find_stream_info(pFormatCtx, nullptr);

for (uint i = 0; i < pFormatCtx->nb_streams; i++)

 {

   if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)

   {

     videoStream = static_cast<int>(i);

     break;

   }



 }



av_read_play(pFormatCtx);    //play stream

pCodec = avcodec_find_decoder(pFormatCtx->streams[videoStream]->codecpar->codec_id);

AVCodecParameters *codec_param = pFormatCtx->streams[videoStream]->codecpar;

avcodec_parameters_to_context(input_codec_ctx, codec_param);

avcodec_open2(input_codec_ctx, pCodec, nullptr);



AVPacket packet;

AVPacket *pkt  = &packet;

AVFrame *frame;

frame = av_frame_alloc();



av_init_packet(pkt);

pkt->data = nullptr;    // packet data will be allocated by the encoder

pkt->size = 0;



while(true){

    av_read_frame(pFormatCtx,pkt);

    avcodec_send_packet(input_codec_ctx,pkt);

    avcodec_receive_frame(input_codec_ctx,frame);

}

Initialization and stuff omitted. Console output for custom decoding:

NULL @ 0x1fb7b80] Opening 'stream.sdp' for reading

[sdp @ 0x1fb7b80] Format sdp probed with size=2048 and score=50

[sdp @ 0x1fb7b80] video codec set to: h264

[sdp @ 0x1fb7b80] RTP Packetization Mode: 1

[udp @ 0x1f34140] end receive buffer size reported is 131072

[udp @ 0x1fb8e40] end receive buffer size reported is 131072

[sdp @ 0x1fb7b80] setting jitter buffer size to 500



 Success !

[sdp @ 0x1fb7b80] Before avformat_find_stream_info() pos: 181 bytes read:181 seeks:0 nb_streams:1

[AVBSFContext @ 0x1fa5880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[AVBSFContext @ 0x1fa5880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[AVBSFContext @ 0x1fa5880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[AVBSFContext @ 0x1fa5880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[AVBSFContext @ 0x1fa5880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[AVBSFContext @ 0x1fa5880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[AVBSFContext @ 0x1fa5880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[AVBSFContext @ 0x1fa5880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[AVBSFContext @ 0x1fa5880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[AVBSFContext @ 0x1fa5880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] Format yuv420p chosen by get_format().

[h264 @ 0x1fa51c0] Reinit context to 1920x1088, pix_fmt: yuv420p

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 57 packets

[h264 @ 0x1fa51c0] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] Invalid level prefix

[h264 @ 0x1fa51c0] error while decoding MB 2 36

[h264 @ 0x1fa51c0] concealing 3887 DC, 3887 AC, 3887 MV errors in I frame

[h264 @ 0x1fa51c0] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 155 packets

[h264 @ 0x1fa51c0] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] corrupted macroblock 32 41 (total_coeff=-1)

[h264 @ 0x1fa51c0] error while decoding MB 32 41

[h264 @ 0x1fa51c0] concealing 3257 DC, 3257 AC, 3257 MV errors in I frame

[h264 @ 0x1fa51c0] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1fa51c0] nal_unit_type: 5(IDR), nal_ref_idc: 3

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 52 packets

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 51 packets

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 10 packets

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 50 packets

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 52 packets

[sdp @ 0x1fb7b80] All info found

[sdp @ 0x1fb7b80] After avformat_find_stream_info() pos: 181 bytes read:181 seeks:0 frames:28

found video stream 



The number of elements in stream is  1 



[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] Format yuv420p chosen by get_format().

[h264 @ 0x1ee3880] Reinit context to 1920x1088, pix_fmt: yuv420p

[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 256 packets

[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] Invalid level prefix

[h264 @ 0x1ee3880] error while decoding MB 119 41

[h264 @ 0x1ee3880] concealing 3170 DC, 3170 AC, 3170 MV errors in I frame

[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 5 packets

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 4 packets

[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] out of range intra chroma pred mode

[h264 @ 0x1ee3880] error while decoding MB 100 56

[h264 @ 0x1ee3880] corrupted macroblock 84 65 (total_coeff=-1)

[h264 @ 0x1ee3880] error while decoding MB 84 65

[h264 @ 0x1ee3880] concealing 754 DC, 754 AC, 754 MV errors in I frame

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 160 packets

[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] corrupted macroblock 17 36 (total_coeff=-1)

[h264 @ 0x1ee3880] error while decoding MB 17 36

[h264 @ 0x1ee3880] concealing 3872 DC, 3872 AC, 3872 MV errors in I frame

[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[sdp @ 0x1fb7b80] max delay reached. need to consume packet

[sdp @ 0x1fb7b80] RTP: missed 53 packets

[h264 @ 0x1ee3880] nal_unit_type: 7(SPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 8(PPS), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] nal_unit_type: 5(IDR), nal_ref_idc: 3

[h264 @ 0x1ee3880] corrupted macroblock 62 39 (total_coeff=-1)

[h264 @ 0x1ee3880] error while decoding MB 62 39

[h264 @ 0x1ee3880] concealing 3467 DC, 3467 AC, 3467 MV errors in I frame

In the end I solved it by implementing it the same way ffplay does: One thread performs av_read_frame() and pushes the received packets to a packetqueue, and a second thread decodes the packets.

No idea why it does not work in one thread.

You might get an example from the following snippets:

PacketReceiver:

must_abort = false; // class member, externally set to true if abort requested

AVPacket packet;

AVPacket *pkt  = &packet;

int ret;



while (must_abort == false){

    ret = av_read_frame(pFormatCtx,pkt);

    if (ret>=0 && !must_abort){

        queue->putPacket(pkt);

    }

    else{

        qDebug("no packet received");

    }

    QApplication::processEvents();

}

PacketQueue:

class PacketQueue{

public:

void init(){

    abort_request = false;

}

void putPacket(AVPacket *pkt) {



    mutex.lock();

    queue.enqueue(*pkt);

    waitForNewPacket.wakeAll();

    mutex.unlock();

}



int getPacket(AVPacket *pkt){

    int ret;

    mutex.lock();

    forever {

        if (abort_request) {

            ret = -1;

            break;

        }

        if (queue.size() == 0){

            if (waitForNewPacket.wait(&mutex, 1000)){

            }else{

                qDebug("PacketQueue timeout, try again...");

            }

            continue;

        }

        *pkt= queue.dequeue();

        ret = 1;

        break;

    }



    mutex.unlock();

    return ret;

}



void abort(){

    mutex.lock();

    abort_request = true;

    mutex.unlock();

}



bool abort_request;

QQueue<AVPacket> queue;

QMutex mutex;

QWaitCondition waitForNewPacket;

};

Decoder:

AVFrame *frame = av_frame_alloc();

AVFrame *frame_RGB = av_frame_alloc();

struct SwsContext *img_convert_ctx = nullptr;

int ret;

int cnt = 0;

int width_current = 0;

int height_current = 0;



avcodec_flush_buffers(mData->input_codec_ctx);



forever{

    cnt++;

    ret = decodeFrame(frame);

    if (ret < 0 ){

        break;

    }

    if (ret == 0){

        continue;

    }



    // check if height and width have changed

    if (width_current != frame->width || height_current != frame->height){

        av_frame_free(&frame_RGB);

        frame_RGB = av_frame_alloc();

        frame_RGB->width = width_current = frame->width;

        frame_RGB->height = height_current = frame->height;

        frame_RGB->format = AV_PIX_FMT_RGB24;

        av_image_alloc(frame_RGB->data, frame_RGB->linesize, frame_RGB->width, frame_RGB->height, AV_PIX_FMT_RGB24, 32);

        img_convert_ctx = sws_getContext(   frame->width,

                                            frame->height,

                                            static_cast<AVPixelFormat>(frame->format),

                                            frame->width,

                                            frame->height,

                                            AV_PIX_FMT_RGB24,

                                            SWS_BICUBIC,

                                            nullptr, nullptr, nullptr);

    }



    if (img_convert_ctx != nullptr) {

        sws_scale(img_convert_ctx, static_cast<uint8_t const * const  *>(frame->data),

                  frame->linesize, 0, frame->height,

                  frame_RGB->data, frame_RGB->linesize);

        // here is the frame available as RGB in frame_RGB

    }



    av_frame_unref(frame);



}



}



int VideoDecoder::decodeFrame(AVFrame* frame){

int ret = AVERROR(EAGAIN);



forever {

    AVPacket pkt;



    do {

        ret = avcodec_receive_frame(input_codec_ctx, frame);

        if (ret >= 0) {

            //frame->pts = frame->pkt_dts;

            //frame->pts = frame->best_effort_timestamp;

        }



        if (ret == AVERROR_EOF) {

            avcodec_flush_buffers(input_codec_ctx);

            return 0;

        }

        if (ret >= 0)

            return 1;

    } while (ret != AVERROR(EAGAIN));



    if (queue->getPacket(&pkt) < 0)

        return -1;        



    ret = avcodec_send_packet(input_codec_ctx, &pkt);



    if (ret == AVERROR(EAGAIN)) {

        qFatal("Receive_frame and send_packet both returned EAGAIN, which is an API violation.");

    }



    if (pkt.buf->buffer != nullptr){

        av_packet_unref(&pkt);

    }else{

        qDebug() << "Packet cannot be freed, pkt.buf->buffer == NULL!";

    }



}

}