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• Silence "string-plus-int" warning shown by clang.

  6 janvier 2020, par Carl Eugen Hoyos

  Silence "string-plus-int" warning shown by clang.
  libswscale/utils.c:89:42 : warning : adding 'unsigned long' to a string does not append to the string [-Wstring-plus-int]
  

  • [DH] libavcodec/utils.c
  • [DH] libavdevice/avdevice.c
  • [DH] libavfilter/avfilter.c
  • [DH] libavformat/utils.c
  • [DH] libavutil/utils.c
  • [DH] libpostproc/postprocess.c
  • [DH] libswresample/swresample.c
  • [DH] libswscale/utils.c

• 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.

• 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();
  
  }