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• ffmpeg and docker result in averror_invaliddata

  1er août 2018, par Wayne

  I am running ffmpeg within a docker container, and I am having a problem.

  I have a wittled-down debug program (listing below) that simply opens (and reads) a test.mp4 I open the file with fopen(), read and print the first 32 bytes. The values agree and are correct whether running in docker or locally. (ie. the file is accessible and readable in the docker container) However, when it gets to avformat_open_input() :

  Running locally : Works just fine. (and the real program fully decodes it)

  Running in docker container : The call to avformat_open_input() fails with AVERROR_INVALIDDATA. This is with test.mp4 in the docker directory.

  I’m a bit lost at this point. I appreciate any ideas.

  test program listing : =========================================

  #include 
  
  extern "C" {
  
  #include <libavformat></libavformat>avformat.h>
  
  }
  
  
  
  int main (int argc, char **argv)
  
  {
  
      int erc=0;
  
      AVFormatContext* srcFmtCtx = NULL;
  
      const char* srcFile = "test.mp4";
  
  
  
      // Simple read/echo
  
      FILE *f = fopen(srcFile, "rb");
  
      printf("fopen() %s  0x%lx\n", srcFile, (unsigned long)f);
  
      for (int i=0; i&lt;4; i++) {
  
          long val;
  
          erc = fread(&amp;val, 1, sizeof(long), f); 
  
          printf("[%d]0x%lx ", i, val);
  
      }   
  
      printf("\n");
  
      fclose(f);
  
  
  
      // Open source with ffmpeg libavformat utils
  
      printf("avformat_open_input(): %s\n", srcFile);
  
      if ((erc = avformat_open_input(&amp;srcFmtCtx, srcFile, NULL, NULL)) &lt; 0) {
  
          printf("avformat_open_input(): Returned AvError: %d\n", erc);
  
          exit(1);
  
      }   
  
      printf("avformat_open_input(): Returned normally\n");
  
      avformat_close_input(&amp;srcFmtCtx);
  
  }

• ffmpeg no re-encode upload finishes too early

  15 octobre 2022, par Amine Tbaik

  I have a pre-encoded video according to youtube recommendations, and I set ffmpeg to upload it without another re-encode. after 20 seconds youtube says the stream ended.
  
while I can see in my terminal that ffmpeg is still running and sending up data.
  
my ffmpeg command is :

  


  ffmpeg -i video.flv -vcodec copy -acodec copy -f flv "rtmp://a.rtmp.youtube.com/live2/my_key"


  


  my understanding is the upload happens so fast (I have 1Gbps fiber internet) while ffmpeg processor is still running in the background on my terminal.
  
is that the case ? is there anything I can do about it or to fix this ?

  


• Parallel video transcoding using hardware acceleration

  26 août 2021, par igrinis

  I'm trying to simultaneously transcode multiple videos using ffmpeg. I do see substantial speed gain when using GPU on a single video file. When transcoding a single file the GPU load is quite low (about 15%), so I thought that I could run several processes in parallel. But running even two transcoding tasks in parallel takes almost 2x time. Why parallelization does not work ?

  


  I'm using AWS g4dn.2xlarge instance with Tesla T4 GPU and running a simple command like

  


  ffmpeg -hwaccel cuvid -c:v h264_cuvid -y -i src.mkv -c:v h264_nvenc -b:v 300k out.mp4


  


  Any help/insights on how to accelerate massive video transcoding is greatly appreciated.