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• SVT-AV1 : After encoding the video seeking is very bad in any video player (even HTML5)

  18 juin 2020, par Viktor Machnik

  i am using SVT-AV1 and FFMPEG to encode Videos into the AV1 video and opus audio codec (.webm), it works fine, except that the video seeking do not work really (extremly bad). When i seek, the CPU useage jumps up and it takes up to minutes until the seeking process finishes.

  



  Here is how i encode the videos :

  



  

  1. Convert any video into yuv : ffmpeg -i  -preset veryslow -level 6.2 .yuv

  


  2. First AV1 run svt-av1 -i '.yuv' -w  -h  --fps  --rc 0 -q 30 --preset 8 -b '.\output1.ivf' --output-stat-file '.\stat_file.stat' --keyint 1 --enable-restoration-filtering 1

  


  3. Second AV1 run svt-av1 -i '.yuv' -w  -h  --fps  --rc 0 -q 30 --preset 3 -b '.\output.ivf' --input-stat-file '.\stat_file.stat' --keyint 1 --enable-restoration-filtering 1

  


  4. Get source video audio in opus codec ffmpeg -i  -c:a libopus -vn -preset veryslow -level 6.2 output.ogg

  


  5. Get final .webm video ffmpeg -i output.ivf -i output.ogg -c copy output.webm

  


  



  I have allready tryed to play with the —keyin option, also just letting it away and use the encoder default, but the results are always the same. (--keyin 1 seems to work better than without this option, but also very very bad)

  



  What am i doing wrong ?

  



  Extras : I am using Windows 10 with downloaded version of SVT-AV1 and FFMPEG (I just renamed the SVT-AV1 Encoder .exe file to be svt-av1.exe). Used CPU is Ryzen 9 3900X

  


• Why android video player that based on ffmpeg can't sync video' time and audio's time ?

  6 juillet 2021, par ZSpirytus

  Background

  


  Recently, I use ffmpeg to write my first Android video player. But video channel's time is faster than audio channel's time about 2 3 times.

  


  Question

  


  Why android video player audio and video is out of sync ? Video is about faster than audio 2 3 times. Thanks for your reading and answers.

  


  Code

  


  In short, I use PacketDispatcher to read AVPacket from http hlv source :

  


  void PacketDispatcher::RealDispatch() {
    while (GetStatus() != DISPATCHER_STOP) {
        ...

        AVPacket *av_packet = av_packet_alloc();
        int ret = av_read_frame(av_format_context, av_packet);

        // PacketDispatcher is who read the AVPacket from http hlv source 
        // and dispatch to decoder by its stream index.
        decoder_map[av_packet->stream_index]->Push(av_packet);
    }
}


  


  And then, Decoder written by Producer-Consumer Pattern, Decoder maintain a queue that store all the AVPacket received from PacketDispatcher. The code like this :

  


  // write to the queue
void BaseDecoder::Push(AVPacket *av_packet) {
    ...
    av_packet_queue.push(av_packet);
    ...
}

// real decode logic
void BaseDecoder::RealDecode() {
    ...
    while (true) {
        // read frame from codec
        AVFrame *av_frame = av_frame_alloc();
        ret = avcodec_receive_frame(av_codec_ctx, av_frame);

        void *decode_result = DecodeFrame(av_frame);
        // send to render
        m_render->Render(decode_result);
    }
}


  


  And then, I do rendering logic in Render. Render also written by Producer-Consumer Pattern, it maintain a queue that store AVFrame received from Decoder, the code like this :

  


  // write AVFrame
void BaseRender::Render(void *frame_data) {
    ...
    frame_queue.push(frame_data);
    ...
}

// render to surface or Open SL
void BaseRender::RealRender() {
    if (m_render_synchronizer && m_render_synchronizer->Sync(frame_data)) {
        continue;
    }
}


  


  Finally, the synchronizer will decide to sleep time or drop video frame according to the frame pts, frame pts is :

  


  frame_data->pts = av_frame->best_effort_timestamp * av_q2d(GetTimeBase());


  


  Also, video extra delay is :

  


  frame_data->video_extra_delay = av_frame->repeat_pict * 1.0 / fps * 2.0;


  


  RenderSynchronizer code like this :

  


  bool RenderSynchronizer::Sync(void *frame_data) {&#xA;    auto base_frame_data = static_cast<baseframedata>(frame_data);&#xA;    if (base_frame_data->media_type == AVMEDIA_TYPE_AUDIO) {&#xA;        audio_pts = pcm_data->pts;&#xA;        return false;&#xA;    } else if (base_frame_data->media_type == AVMEDIA_TYPE_VIDEO) {&#xA;        video_pts = rgba_data->pts;&#xA;        return ReceiveVideoFrame(static_cast<rgbadata>(frame_data));&#xA;    }&#xA;    return false;&#xA;}&#xA;&#xA;bool RenderSynchronizer::ReceiveVideoFrame(RGBAData *rgba_data) {&#xA;    if (audio_pts &lt;= 0 || video_pts &lt;= 0) {&#xA;        return false;&#xA;    }&#xA;&#xA;    double diff = video_pts - audio_pts;&#xA;    if (diff > 0) {&#xA;        if (diff > 1) {&#xA;            av_usleep((unsigned int) (rgba_data->extra_delay * 1000000.0));&#xA;        } else {&#xA;            av_usleep((unsigned int) ((diff &#x2B; rgba_data->extra_delay) * 1000000.0));&#xA;        }&#xA;        return false;&#xA;    } else if (diff &lt; 0) {&#xA;        LOGD(TAG, "drop video frame");&#xA;        return true;&#xA;    } else {&#xA;        return false;&#xA;    }&#xA;}&#xA;</rgbadata></baseframedata>

  


• Getting color mismatch while converting from NV12 raw data to H264 using FFMPEG

  29 janvier 2019, par Harshil Makwana

  I am trying to convert NV12 raw data to H264 using hw encoder of FFMPEG.

  to pass raw data to encoder I am passing AVFrame struct using below logic :

      uint8_t * buf;
  
      buf = (uint8_t *)dequeue();
  
      frame->data[0] = buf;
  
      frame->data[1] = buf + size;
  
      frame->data[2] = buf + size;
  
      frame->pts = frameCount;
  
      frameCount++;

  but using this logic, I am getting, color mismatched H264 data,

  Can someone tell me , How to pass buffer to AVFrame data ?

  Thanks in Advance,
  Harshil