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• Output video segments via a pipe using FFmpeg

  6 janvier 2019, par Joey Morani

  My Node.js app uses FFmpeg to capture video of a DirectShow device and then output segments for live streaming (HLS). At the moment I’m outputting the segments to files, however if I could output them via a pipe it would allow me to efficiently send the segment via a websocket instead of hosting a HTTP server.

  I’ve tried using this command :

  ffmpeg -y -f dshow -i video=FFsource:audio=Stereo Mix (Realtek High
  Definition Audio) -vcodec libvpx -acodec libvorbis -threads 0 -b:v
  3300k -cpu-used 5 -keyint_min 150 -g 150 -map 0 -flags:v
  +global_header -f segment -

  However it gives the error "Could not write header for output file #0 (incorrect codec parameters ?) : Muxer not found". This commands works for outputting to files (by replacing ’-’ with ’seg_%03d.webm’).

  Does FFmpeg not support pipes for segmented video, or is there something wrong with the command ? Thanks.

• An efficient way to use Windows Named Pipe for IPC

  26 juillet 2020, par Ehsan5

  I am using jna module to connect two processes that both perform FFMPEG commands. Send SDTOUT of FFMPEG command on the server side to NampedPipe and receive STDIN from that NampedPipe for other FFMPEG command on the Client side.

  


  this is how I capture STDOUT and send into the pipe in server Side :

  


  InputStream out = inputProcess.getInputStream();
byte[] buffer = new byte[maxBufferSize];
while (inputProcess.isAlive()) {
     int no = out.available();
     if (no > 0 && no > maxBufferSize) {
        int n = out.read(buffer, 0,maxBufferSize);
        IntByReference lpNumberOfBytesWritten = new IntByReference(maxBufferSize);
        Kernel32.INSTANCE.WriteFile(pipe, buffer, buffer.length, lpNumberOfBytesWritten, null);
     }
}


  


  And this is how I capture STDIN and feed it to the Client Side :

  


  OutputStream in = outputProcess.getOutputStream();
while (pipeOpenValue >= 1 && outputProcess.isAlive() && ServerIdState) {
      // read from pipe
      resp = Kernel32.INSTANCE.ReadFile(handle, readBuffer,readBuffer.length, lpNumberOfBytesRead, null);
      // Write to StdIn inputProcess
      if (outputProcess != null) {
          in.write(readBuffer);
          in.flush();
      }
      // check pipe status
      Kernel32.INSTANCE.GetNamedPipeHandleState(handle, null,PipeOpenStatus, null, null, null, 2048);
      pipeOpenValue = PipeOpenStatus.getValue();
      WinDef.ULONGByReference ServerId = new WinDef.ULONGByReference();
      ServerIdState = Kernel32.INSTANCE.GetNamedPipeServerProcessId(handle, ServerId);
}


  


  But I faced two problems :

  


  

  1. High CPU usage due to iterating two loops in Server and Client. (find by profiling resources by VisualVM)

  


  2. Slower operation than just connecting two FFMPEG command with regular | in command prompt. Speed depends on buffer size but large buffer size blocks operation and small buffer size reduce speed further.

  


  


  Questions :

  


  

  1. Is there any way not to send and receive in chunks of bytes ? Just stream STDOUT to the Namedpipe and capture it in Client. (Eliminate two Loops)

  


  2. If I cant use NampedPipe, is there any other way to Connect two FFMPEG process that runs in different java modules but in the same machine ?

  


  


  Thanks

  


• fftools/ffmpeg_demux : prefer fd over pipe for seek support

  14 décembre 2022, par Zhao Zhili

  fftools/ffmpeg_demux : prefer fd over pipe for seek support
  Signed-off-by : Zhao Zhili <zhilizhao@tencent.com>
  

  • [DH] fftools/ffmpeg_demux.c