Sur d’autres sites (12316)

• How can I learn the effective quality of the h264_nvenc encoder ?

  24 septembre 2020, par pfdint2

  I seek to ascertain the end-product quality of various cq ("constant quality") values for the h264_nvenc video encoder.

  


  To use the h264_nvenc encoder through ffmpeg and with a target quality, I follow the instructions in Nvidia's documentation, last paragraph of the linked anchor.

  


  I specify a Variable Bit Rate rate control mode (rc=vbr_hq) and a target quality (cq=). This should be enough to test various values of cq. The story should end there.

  


  HOWEVER, that only outputs the same perfect quality video of extremely large size for any cq value. (Using cq=1, cq=20, and cq=51 all output a file with the same hash.)

  


  Per documentation, I can also specify a maxBitRate (maxrate=). If I don't specify a maxrate, the documentation indicates :

  


  


  If maxBitRate is not specified, the encoder will use as many bits as needed to achieve the target quality.

  


  


  But that's not the behavior I'm observing. I'm seeing the encoder use as many bits as possible, not as many bits as needed. The resultant video has an overall bitrate of 100Mb/s. Double the source video.

  


  If I do set a maxrate, it is observed by the encoder. But if I have to set the bitrate correctly for every cq value, what is the point of the cq value ? I would just set cq=1 and test various bitrates, which would then only be applicable to a specific video.

  


  Is there some warning or output that notes that the bitrate was insufficient to reach the target quality that I'm not seeing ? That would at least allow me to brute force this.

  


  Or am I misunderstanding the relationship between these settings ?

  


• How to Terminate a Process Normally Created using ProcessBuilder

  21 août, par Bilal Ahmed Yaseen

  I am creating Processes using ProcessBuilder in my Java Application. The created process executes some FFMPEG commands which actually copy the RTSP streams in specified destination media file.

  


  ProcessBuilder builder = new ProcessBuilder("ffmpeg", "-i", RTSP_URL, "-f", fileFormat, destFilePath);
Process processToExecute = builder.start();


  


  I want to close the process before it completes its execution. So, If I run this FFMPEG command directly in windows CMD and then press 'CTRL+C' after 5 seconds then process get terminates with status '2'. And I can play the media file created so far.

  


  So, If I do the same operation in my Java Application using :

  


   process.destroy(); //I call this method after 5 sec


  


  I get the status code '1' which means abnormal termination. I get the status by the following way :

  


   processToExecute.destroy();
 processToExecute.exitValue(); //This return me status '1'


  


  And I can't play the media file and I think this is due to the abnormal termination of the process.

  


  So how I can terminate the process created using ProcessBuilder in the same way we do in CMD with (CTRL+C) so that I may play the created media file ?

  


  I want to terminate process (created using ProcessBuilder) in Java Application with status code of '2' that I get when I terminate process using CMD.

  


  EDIT#01 : --- Sharing Findings

  


  So, when I try to delete that file once app terminates, I get the following error :

  


  The Action Can't be Performed Because File is Opened in FFMPEG.exe


  


  Which means that process is not terminating the command it is executing. That command still has occupied this file that's why I am not getting able to play it. Process gets terminate when I call :

  


   processToExecute.destroy();


  


  But, the task it is performing (that is execution of a command) is still active. Strange !!!!

  


  EDIT#02 : Sharing Ultimate Reason

  


  Actually If I directly press 'CTRL+C' or 'q' in cmd when process is running then it terminates the process successfully and this process is no more visible in the currently executing processes lists.

  


  And Programatically when I call method :

  


  cmd> processToExecute.destroy();


  


  It terminates the process but when I see the list of currently executing processes I can still see them over there.

  


  And same scenario exists If I try to terminate this process using 'taskkill' or 'kill' command in another CMD by specifying their's name or pid that still process terminates abnormally.

  


  P.S. I use the following command to see the running processes :

  


  tasklist


  


  So from this it proves that destroy() method from Application and 'taskkill or kill' command from another CMD is not terminating the process normally that pressing 'CTRL+C' and 'q' does.

  


• How to Terminate a Process Normally Created using ProcessBuilder

  30 janvier 2015, par Bilal Ahmed Yaseen

  I am creating Processes using ProcessBuilder in my Java Application. The created process executes some FFMPEG commands which actually copy the RTSP streams in specified destination media file.

  ProcessBuilder builder = new ProcessBuilder("ffmpeg", "-i", RTSP_URL, "-f", fileFormat, destFilePath);
  
  Process processToExecute = builder.start();

  I want to close the process before it completes its execution. So, If I run this FFMPEG command directly in windows CMD and then press ’CTRL+C’ after 5 seconds then process get terminates with status ’2’. And I can play the media file created so far.

  So, If I do the same operation in my Java Application using :

   process.destroy(); //I call this method after 5 sec

  I get the status code ’1’ which means abnormal termination. I get the status by the following way :

   processToExecute.destroy();
  
   processToExecute.exitValue(); //This return me status '1'

  And I can’t play the media file and I think this is due to the abnormal termination of the process.

  So how I can terminate the process created using ProcessBuilder in the same way we do in CMD with (CTRL+C) so that I may play the created media file ?

  I want to terminate process (created using ProcessBuilder) in Java Application with status code of ’2’ that I get when I terminate process using CMD.

  EDIT#01 : --- Sharing Findings

  So, when I try to delete that file once app terminates, I get the following error :

  The Action Can't be Performed Because File is Opened in FFMPEG.exe

  Which means that process is not terminating the command it is executing. That command still has occupied this file that’s why I am not getting able to play it. Process gets terminate when I call :

   processToExecute.destroy();

  But, the task it is performing (that is execution of a command) is still active. Strange !!!!

  EDIT#02 : Sharing Ultimate Reason

  Actually If I directly press ’CTRL+C’ or ’q’ in cmd when process is running then it terminates the process successfully and this process is no more visible in the currently executing processes lists.

  And Programatically when I call method :

  cmd> processToExecute.destroy();

  It terminates the process but when I see the list of currently executing processes I can still see them over there.

  And same scenario exists If I try to terminate this process using ’taskkill’ or ’kill’ command in another CMD by specifying their’s name or pid that still process terminates abnormally.

  P.S. I use the following command to see the running processes :

  tasklist

  So from this it proves that destroy() method from Application and ’taskkill or kill’ command from another CMD is not terminating the process normally that pressing ’CTRL+C’ and ’q’ does.