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• `FFmpeg` `segment_time` inserts blank frames at the beginning of segment

  27 août 2017, par asdf

  I am using the following command to cut videos in parts.
  I need parts to be less than passed max_length param, I do not need precise cuts.

  ffmpeg -i input.mov \
  
  -segment_time 20 -f segment -reset_timestamps 1 input_%d.mov

  Every first part video file cut by ffmpeg is not 20s, but 20.5s long. And it has several black frames at the beginning inserted by ffmpeg.

  I don’t mind having 19.5s long parts if that is needed because of keyframes. But I need to get rid of those black frames at the beginning so that videos cut in parts could be concatenated in a single video later without any troubles.

  Could you give me an advice ?

  ---

  Upd :

  There were no black frames in an original video which was 23 seconds long.
  I made a cut setting 12 as a segment length.

  I also had to add -c copy because I would like to keep original quality if that’s possible.

  Leading black frames were added after a cut to part 1 which is 12 seconds long.

  Trailing black frames were added after a cut to part 2 which is 10 seconds long.

  https://www.dropbox.com/sh/zo8evta3w1xho3o/AABpTB3w3CuPa1WcghkSIVfna?dl=0

  The command used was

  ffmpeg -y -i /Users/nt/Desktop/cut/AAL_CrSlowMo_041413_1.mov -c copy -segment_time 12 -f segment -reset_timestamps 1 /Users/nt/Desktop/cut/AAL_CrSlowMo_041413_1_%d.mov

  Here’s output of ffmpeg :
  https://gist.github.com/nmtitov/ad102539f95fa03b95f10a46f8d99663

• Record local audio in a docker container

  17 juillet 2015, par pablo

  How can I record the audio of an application like Firefox inside a docker container with ffmpeg ?
  I’ve found examples how to forward pulseaudio to the host - netflix, skype.

  When I’m trying to use pactl :

  pactl list sources

  Or

  docker exec -it  bash
  
  apt-get install pulseaudio
  
  pactl load-module module-native-protocol-unix auth-anonymous=1 socket=/tmp/.pulse-socket

  I’m getting an error :

  Connection failure: Connection refused
  
  pa_context_connect() failed: Connection refused

  This also fail

  ffmpeg -f pulse -i default /tmp/pulse.wav

• mp4 is not playing on changing the name of mp4 file

  7 juillet 2014, par user2301309

  I am using below code to generate file name-

          File imagefile = new File(path);
  
          int imageCount = 0;
  
          if (!imagefile.exists()) {
  
              imagefile.mkdirs();
  
          }else{
  
              String[] files = imagefile.list();
  
              for(String file : files){
  
                  if(file.contains("mp4")){
  
                      String fileName = file.replace(".mp4","");
  
                      String[] parts = fileName.split("_");
  
                      String count  = parts[parts.length-1].replaceAll("\\D+","");
  
                      int i = Integer.parseInt(count);
  
                      if(i+1>imageCount){
  
                          imageCount = i+1;
  
                      }
  
                  }
  
              }
  
          }
  
          String video_id = "VID"+ "_" + imageCount;
  
          String video_info = (Lat_Lon_CellID.lat+"#"+Lat_Lon_CellID.lon+"#"+Lat_Lon_CellID.datetimestamp+"#"+Home.imei+"#").replaceAll("\\.", "@");
  
          newVideoPath = path + File.separator +video_info+ video_id + ".mp4";

  videofile name generated here is 0@0#0@0#null#354961053417767#VID_0.mp4

  but when i try to play this video, i got error MediaPlayer error (1, -2147483648) while if i change newVideoPath to-

      String video_id = "VID"+ "_" + imageCount;
  
          newVideoPath = path + File.separator + video_id + ".mp4";

  videofile name generated here is VID_0.mp4

  then it plays the video.
  Can anyone tell me that what could be the reason ?