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• Ffmpeg cpp libav randomly uses high cpu and less gpu or uses high gpu and less cpu with hw accel

  29 avril 2024, par cngkyt

  I am using ffmpeg as library with cpp
the integration of library is perfectly done i am using AVFilterGraph as audio resampler and video pixfmt converter.

  


  I cannot share code because it is a complete library and contains too many files but i can assure there is no problem about code but maybe approach.

  


  My whole class is based on the transcode example of ffmpeg
text

  


  The problem is when i run my program that encodes approx 90 streams

  


  it starts with 25% cpu usage 80% gpu encode usage %85 gpu decode usage with 100% sm utilization

  


  or

  


  it starts with 80% cpu usage 45% gpu encode usage 50% gpu decode usage with 60% sm utilization

  


  when it start like second type of utilization videos are perfect
but when it starts like the first type of utilization videos are freezing

  


  my program uses pure gpu for encoding for all streams but using gpu decoding for every 3 cpu deoding
that means i use hwaccel for 1/3 of streams
because my cards are 4070 ti super and they have 2 NVENC 1 NVDEC chips

  


  my program takes udp streams and encode it and outputs udp mpegts

  


  bitrate and quality settings are persistent across streams depending on resolution

  


  i always test on same streams

  


  the problem happens randomly
but if it starts with high cpu and low gpu utilization it goes on like this
when i restart program problem occurs randomly again

  


  what can couse this

  


  just as an info i have experience on c++ more than 25 years

  


  if there is someone who can teach me something i will be happy

  


  thanks for your further helps

  


  i have tried to reproduce it with compiled ffmpeg instead of my libav library usage
same thing happens but not often

  


  i have tried using hevc_cuvid instead of hwacceleration with avcodec_find_decoder_by_name function

  


• FFMPEG stream video to Youtube Live

  13 juin 2022, par BlessedHIT

  I have a mov file and I'm using ffmpeg to stream it to youtube live using the following command,

  


  ffmpeg -re -i "episode.mov" -pix_fmt yuvj420p -x264-params keyint=48:min-keyint=48:scenecut=-1 -b:v 4500k -b:a 128k -ar 44100 -acodec aac -vcodec libx264 -preset medium -crf 28 -threads 4 -f flv "rtmp://a.rtmp.youtube.com/live2/YOUTUBE.LIVESTREAM.KEY"


  


  But im getting the following message on youtube,

  


  YouTube is not receiving enough video to maintain smooth streaming. As such, viewers will experience buffering


  


  My ffmpeg output showed my bitrate being between 800 - 1000 mbps, way lower than what i have specified in my ffmpeg command.

  


  I am using a not so powerful virtual machine, and so i thought this might be why i am not getting the desired bitrate.

  


  To overcome my hardware limitations, I then decided to encode the file for streaming using this command :

  


  ffmpeg -i episode.mov -c:v libx264 -preset medium -b:v 4500k -maxrate 4500k -bufsize 6000k -vf "scale=1280:-1,format=yuv420p" -g 50 -c:a aac -b:a 128k -ac 2 -ar 44100 episode.flv


  


  Then I stream copy the file using :

  


  ffmpeg -re -i episode.flv -c copy -f flv "rtmp://a.rtmp.youtube.com/live2/YOUTUBE.LIVESTREAM.KEY"


  


  And that seems to give me a stream that youtube is happy with.

  


  My question is, is there a way I can rewrite my ffmpeg command to livestream with the desired bitrate without needing to first encode my mov to another file or is adding more memory the only way forward here ?

  


• Audio tracks while merging multiple videos using FFMPEG in Android ?

  23 avril 2016, par Leonti

  I have problem in video processing in Android.

  To merging multiple videos, I’m now using ffmpeg c++ library and JavaCV.

  Here is my code :

  protected Void doInBackground(String... params) {
  
      String firstVideo = params[0];
  
      String secondVideo = params[1];
  
      String outPutVideo = params[2];
  
  
  
      try {
  
          FrameGrabber grabber1 = new FFmpegFrameGrabber(firstVideo);
  
          grabber1.start();
  
          FrameGrabber grabber2 = new FFmpegFrameGrabber(secondVideo);
  
          grabber2.start();
  
          FrameRecorder recorder2 = new FFmpegFrameRecorder(outPutVideo, grabber2.getImageWidth(),
  
                  grabber2.getImageHeight(), grabber1.getAudioChannels());
  
  
  
          recorder2.setVideoCodec(grabber2.getVideoCodec());
  
          recorder2.setFrameRate(grabber2.getFrameRate());
  
          recorder2.setSampleFormat(grabber2.getSampleFormat());
  
          recorder2.setSampleRate(grabber2.getSampleRate());
  
          recorder2.setAudioChannels(2);
  
          recorder2.start();
  
          Frame frame;
  
          int j = 0;
  
  
  
          while ((frame = grabber1.grabFrame()) != null) {
  
              j++;
  
              recorder2.record(frame);
  
          }
  
          while ((frame = grabber2.grabFrame()) != null) {
  
              recorder2.record(frame);
  
          }
  
          recorder2.stop();
  
          grabber2.stop();
  
          grabber1.stop();
  
      } catch (Exception e) {
  
          e.printStackTrace();
  
          success = false;
  
      }
  
      return null;
  
  } 

  First video has no sound, and second video has audio tack.

  Audio of second video starts from start of result video.

  I tried and had search many hours, but cannot find solution. Please give me advise if you have experience !!!