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• avformat/mpeg : Don't copy or leak string in AVBPrint

  4 décembre 2019, par Andreas Rheinhardt

  avformat/mpeg : Don't copy or leak string in AVBPrint
  vobsub_read_header() uses an AVBPrint to write a string and up until
  
  now, it collected the string stored in the AVBPrint via
  
  av_bprint_finalize(), which might involve an allocation and copy of the
  
  string. But this is unnecessary, as the lifetime of the returned string
  
  does not exceed the lifetime of the AVBPrint. So use the string in the
  
  AVBPrint directly.
  This also makes it possible to easily fix a memleak : In certain error
  
  situations, the string stored in the AVBPrint would not be freed (if it
  
  was dynamically allocated). This has been fixed, too.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/mpeg.c

• How to send a string to ffmpeg's input in Java

  19 décembre 2019, par jdauthre

  I am quite new to java, and try as I might, I can’t find any examples to help me. I am running ffmpeg as a process and parsing the stderr to get various bits of data - all of which is working fine, but I want to send a "q\n" command to ffmpeg’s input from a gui menu item to gracefully quit it whilst it is running when necessary. So all I want to do is send a string programmatically to ffmpeg, the equivalent of sending q return from terminal. Thanks in advance
  edit here is the relevant (simplified) section of the code

   private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                 Thread thread = new Thread() {
  
  
  
  public void run()
  
  BufferedReader error_reader,input_reader;
  
  InputStreamReader error_isr,input_isr;
  
  
  
  String ffmpeg_command = "ffmpeg " + overwrite + " -i " + "\"" + currentfilestring + "\"" + " " + stream + " " + test + " " + findsilence + " " + videocodec + " -b:v " + videoqual + " " + audiocodec + " -ac 2  -ab " + audioqual + " " + res + " " + aspectratio + " " + framerate + " " + "\"" + destdir + destfile + "\"";
  
  System.out.println(ffmpeg_command);
  
  try {
  
  OutputStream stdout;
  
  InputStream stdin;
  
  InputStream stderr;
  
  String errorstr,inputstr;
  
  //Run the ffmpeg
  
  Process ffmpeg = Runtime.getRuntime().exec(ffmpeg_command, null, new File(userDir));
  
  
  
  //Get stdin,stderr + stdout                     
  
  stdin = ffmpeg.getInputStream();
  
  stderr = ffmpeg.getErrorStream();
  
  stdout = ffmpeg.getOutputStream();
  
  stdout.write("\r\n".getBytes());   
  
  stdout.flush();
  
  stdout.close();
  
  
  
  error_isr = new InputStreamReader(stderr);
  
  error_reader = new BufferedReader(error_isr);
  
  
  
  input_reader = new BufferedReader(input_isr);
  
  while (!error_reader.ready()) {
  
  }
  
  while ((errorstr = error_reader.readLine()) != null) {
  
  
  
  if(stopconv =="yes"){
  
                              //-------------------------------------------------------------------------------------
  
                                 // TRYING TO INPUT "q\n" TO FFMPEG HERE
  
                 //-------------------------------------------------------------------------------------
  
   }
  
  
  
   error_isr.close();
  
   error_reader.close();
  
   stdin.close();
  
   stderr.close();
  
   jProgressBar1.setValue(0);
  
  
  
   ffmpeg.destroy();
  
  
  
   } catch (Exception e) {
  
   e.printStackTrace();
  
                          }
  
  };
  
  thread.start();
  
  }                             

• Python, FFMPEG : Redirecting output of FFMPEG subprocess call to a string

  31 décembre 2019, par user1452030

  I’ve managed to run an FFMPEG command using the subprocess module as shown below :

  output = subprocess.check_output(command, shell=True)

  This works fine, but it prints the verbose FFMPEG output to console. The program I’m writing is supposed to run for hundreds/thousands of files in a batch and I don’t want detailed outputs for every file processed, unless the user chooses to do so. Can I redirect the console outputs and errors to strings, so that I can decide when I should and shouldn’t print them ?

  This might be lame, but I tried the following snippet :

  outputBuffer = BytesIO()
  
  output = subprocess.check_output(command, shell=True, stdout=outputBuffer)

  But it gave me the following error :

  ValueError: stdout argument not allowed, it will be overridden.

  I saw other examples where the POpen interface was used, but given that I’m not communicating with the external command as it is running, and that I need to run this for a large number of items, I’d prefer something simpler, if possible.

  Thanks in advance !

  Note : I’ve found lots of questions in this broad topic, but I couldn’t find anything perfectly relevant to my situation.