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• Create mp4 file from raw h264 using a pipe instead of files

  16 avril 2019, par Charlie Burns

  I have a raw h264 file that I can display with VLC, on a mac :

  open -a VLC file.h264

  I can convert this to mp4 with the command line

  ffmpeg -f h264 -i file.h264 -c:v copy file.mp4

  But what I really want to do is something like :

  cat file.h264 | ffmpeg > file.mp4

  Reason being that the input is coming over a socket and I want to convert it and send it to a video tag in an html file on the fly.

  An alternative solution would be a way to display the raw h264 in a web page without converting it to mp4 first.

  The input is coming in frame by frame, the first four bytes are 0,0,0,1. My understanding is that this h264 Annex B format.

  I know nothing about video formats, I would grateful to be pointed in a direction to look.

  Should I look into writing code using libavcodec like this quuesion or is there an off-the-shelf solution ?

  H.264 muxed to MP4 using libavformat not playing back

  Thanks !

• Java execute ffmpeg commands with (pipe) "... -f nut - | ffmpeg -i - ..." just hangs

  18 mars 2019, par user3776738

  I can’t get this to run,because java just waits for ffmpeg. But ffmpeg doesn’t give an input- nor an error stream. It just runs, but doing nothing.

  The output of "System.out.println("command :.." insert into bash just runs fine as expected.So there is nothing wrong with the ffmpeg syntax.

  Here’s the code.

  package mypackage;
  
  
  
  import java.awt.image.BufferedImage;
  
  import java.io.BufferedReader;
  
  import java.io.IOException;
  
  import java.io.InputStreamReader;
  
  import javax.imageio.ImageIO;
  
  
  
  /**
  
   *
  
   * @author test
  
   */
  
  public class ffmpeg_hang {
  
  
  
          /**
  
       * @param args the command line arguments
  
       */
  
      public static void main(String[] args) throws IOException, InterruptedException {
  
          String INPUT_FILE="/path/to/media";
  
          String FFMPEG_PATH="/path/to/ffmpegFolder/";
  
  
  
              for(int i=0;(i+4)<40;i+=4){                
  
              String[] ffmpeg_pipe = new String[]{
  
                  FFMPEG_PATH + "ffmpeg_4.1.1",
  
                  "-ss",(i+""),"-t", "4",             
  
                  "-i", INPUT_FILE,                                        
  
                  "-ac", "1", "-acodec", "pcm_s16le", "-ar", "16000", 
  
                  "-f","nut","-","|",
  
                  FFMPEG_PATH + "ffmpeg_4.1.1",
  
                  "-i","-",
  
                  "-lavfi", "showspectrumpic=s=128x75:legend=disabled:saturation=0:stop=8000",
  
                  "-f","image2pipe","pipe:1"};
  
  
  
              System.out.println("command: "+String.join(" ", ffmpeg_pipe));
  
  
  
              Process p;
  
              //ffmpe wav->pipe->spectrogra->pipe->java
  
              p = Runtime.getRuntime().exec(ffmpeg_pipe);
  
  
  
  
  
              StringBuilder Boxbuffer = new StringBuilder();
  
              BufferedReader reader = new BufferedReader(new InputStreamReader(p.getErrorStream()));
  
              String line = "";
  
  
  
              while ((line = reader.readLine()) != null) {
  
                  Boxbuffer.append(line);
  
              }
  
  
  
  
  
              System.out.println("ffmpeg errors->> "+Boxbuffer.toString());
  
              p.waitFor();
  
  
  
  
  
              BufferedImage image = ImageIO.read(p.getInputStream());
  
              //do stuff with image
  
              }
  
  
  
      }
  
  
  
  }

• Streaming video over named PIPE with limited "channel" bandwidth

  13 mars 2019, par fmagno

  I have a video container vid.mp4 that I want to play with ffplay through a named PIPE and be able to tweak the maximum bandwidth allowed by the "channel". Follows what I did :

  1. Create a named PIPE :

  mkfifo pipe_in

  2. Send the container to the pipe with a limited bandwidth (150kB/s) with the help of pipe viewer pv :

  cat vid.mp4 | pv -L 150k > pipe_in

  3. Play the video with ffplay :

  ffplay cache:./pipe_in

  My expectation : To watch the video come through immediately but slowly given the bandwidth constraint.

  What really happens : The video begins to show at normal speed only when command 2. finishes running.

  Thank you in advance !