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• ffmpeg dash Segment offset

  18 mars 2019, par inkubux

  I’m trying to integrate live-transcoding like "plex" or "emby" with my application.

  I am able to serve dash content over to shaka-player or dash.js but only in ’live-mode’. But I want to enable seeking through the player.

  I looked at plex and to enable this they create their own mpd file with duration so the player will have a full seekbar.

  However when seeking the player will ask for a segment number eg : 449. I need to stop ffmpeg and restart with an offset (-ss &lt;<segment>>)</segment>, but ffmpeg will just restart a transcode session from segment 0 with an initial segment.

  What I want is to tell ffmpeg to start at a seekpoint but only output from segment number and now-on.

  When playing with hls and mpegts, I can tell ffmpeg to output at a certain segment : with the option -segment_start_number but this is not available for dash. And plex use their own transcoder based of ffmpeg with the option -skip_to_segment

  I tried to ’hack’ around by keeping a manual offset on my web-server, even if I serve the "supposed" right segment after the seek point dash.js and shaka-player can’t recover the stream.. VLC on the other habd is able to (probably more tolerent) to errors in segments.

  Is the supposed right segment after a seek in dash (contains the initial segment) or only the segment.

  Is ffmpeg able to start segmenting dash as a supposed segment (for seek and resume)

  The same technique works in hls with forced key frames and a custom m3u8 (with all the "predicted" segments) but calculating the right segment length and the right bandwidth is much harder and hackish and dash is more tolerant to variation.

  I would really like to be able to seek through my live transcoding video.

  For reference here is a custom mpd file I serve to enable "seeking" :

  <mpd xmlns="urn:mpeg:dash:schema:mpd:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="static" suggestedpresentationdelay="PT1S" mediapresentationduration="PT49M2.920S" maxsegmentduration="PT2S" minbuffertime="PT10S">
  
      <period start="PT0S" duration="PT49M2.920S">
  
          <adaptationset segmentalignment="true">
  
              <segmenttemplate timescale="1" duration="1" initialization="$RepresentationID$/initial.mp4" media="$RepresentationID$/$Number$.m4s" startnumber="1">
  
              </segmenttemplate>
  
              <representation mimetype="video/mp4" codecs="avc1.640029" bandwidth="3766000" width="1920" height="1080">
  
              </representation>
  
          </adaptationset>
  
          <adaptationset segmentalignment="true">
  
              <segmenttemplate timescale="1" duration="1" initialization="$RepresentationID$/initial.mp4" media="$RepresentationID$/$Number$.m4s" startnumber="1">
  
              </segmenttemplate>
  
              <representation mimetype="audio/mp4" codecs="mp4a.40.2" bandwidth="188000" audiosamplingrate="48000">
  
                  <audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="6"></audiochannelconfiguration>
  
              </representation>
  
          </adaptationset>
  
      </period>
  
  </mpd>

  And here is the ffmpeg command to pull it off :

  ffmpeg -ss 0 -i movie.mkv -y -acodec aac -vcodec libx264 -f dash -min_seg_duration 1000000 -individual_header_trailer 0 -pix_fmt yuv420p -vf scale=trunc(min(max(iw\,ih*dar)\,1920)/2)*2:trunc(ow/dar/2)*2 -bsf:v h264_mp4toannexb -profile:v high -level 4.1 -map_chapters -1 -map_metadata -1 -preset veryfast -movflags frag_keyframe+empty_moov -use_template 1 -use_timeline 0 -remove_at_exit 1 -crf 23 -bufsize 7532k -maxrate 3766k -start_at_zero -threads 0 -force_key_frames expr:if(isnan(prev_forced_t),eq(t,t),gte(t,prev_forced_t+1)) -init_seg_name $RepresentationID$/0_initial.mp4 -media_seg_name $RepresentationID$/0_$Number$.m4s /transcoding_temp/Z1GVWEc/index.mpd

  The media_seg_name is where I prepend the custom seek_point let’s say I want to seek to segment 1233 the template would be :

  -media_seg_name $RepresentationID$/1233_$Number$.m4s

  and the segments would be 1233_1 1233_2 1233_* So I can serve the right segment after seek. but the player does not recover and still downloading subsequent segments. I guess since a new initial segment is generated and I somehow miss headers for continuous playback after seek but I’m probably wrong.

  Thanks for your help

• What is substitute for ffmpeg video filter "between" for audio filter

  18 janvier 2018, par Hekimen

  i want make a short video preview from long video with audio, but i have problem to select audio stream segments on specific timestamps.
  I am using this option for segmenting video

  -filter_complex "[0:v]select='between(t,216,220.5)+between(t,432,436.5)+between(t,648,652.5)+between(t,864,868.5)+between(t,1080,1084.5)+between(t,1296,1300.5)+between(t,1512,1516.5)+between(t,1728,1732.5)+between(t,1944,1948.5)+between(t,2160,2164.5)'[outv]"

  and my question is how this option rewrite for audio stream, because when i use just -filter without selecting any stream then i get error : Cannot connect video filter to audio input

  I am using this ffmpeg version :

  ffmpeg version 3.3.3-static http://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 6.4.0 (Debian 6.4.0-2) 20170724
  configuration : —enable-gpl —enable-version3 —enable-static —disable-debug —disable-ffplay —disable-indev=sndio —disable-outdev=sndio —cc=gcc-6 —enable-fontconfig —enable-frei0r —e
  nable-gnutls —enable-gray —enable-libass —enable-libfreetype —enable-libfribidi —enable-libmp3lame —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-libopus —enable-librtm
  p —enable-libsoxr —enable-libspeex —enable-libtheora —enable-libvidstab —enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx —enable-libwebp —enable-libx264 —enable-libxvid
  libavutil      55. 58.100 / 55. 58.100
  libavcodec     57. 89.100 / 57. 89.100
  libavformat    57. 71.100 / 57. 71.100
  libavdevice    57.  6.100 / 57.  6.100
  libavfilter     6. 82.100 /  6. 82.100
  libswscale      4.  6.100 /  4.  6.100
  libswresample   2.  7.100 /  2.  7.100
  libpostproc    54.  5.100 / 54.  5.100
  

• java.io.IOException : Error running exec() Working Directory : null Environment : null

  16 janvier 2018, par Muhammad Hamza Shahid

  I am using WritingMinds/ffmpeg-android-java in application.

  here is my code

  loadFFmpeg();
  
  String cmd="ffmpeg -i /storage/emulated/0/media/audio/a.mp3 -i  /storage/emulated/0/recording.3gp -filter_complex \"[0:a][1:a]amerge=inputs=2[aout]\" -map \"[aout]\" " + outputFile;
  
  executeFFmpeg(cmd.split(" "));

  and

  private void loadFFmpeg() {
  
      FFmpeg ffmpeg = FFmpeg.getInstance(MainActivity.this.getApplicationContext());
  
      try {
  
          ffmpeg.loadBinary(new LoadBinaryResponseHandler() {
  
  
  
              @Override
  
              public void onStart() {}
  
  
  
              @Override
  
              public void onFailure() {}
  
  
  
              @Override
  
              public void onSuccess() {}
  
  
  
              @Override
  
              public void onFinish() {}
  
          });
  
      } catch (FFmpegNotSupportedException e) {
  
          // Handle if FFmpeg is not supported by device
  
      }
  
  }
  
  
  
  private void executeFFmpeg(String[] cmd)
  
  {
  
      /*String workFolder = getApplicationContext().getFilesDir() + "/ffmpeg";
  
      String environment = Environment.getExternalStorageDirectory().getAbsolutePath();
  
      Map map = new HashMap();
  
      map.put("Working Directory", workFolder);
  
      map.put("Environment",environment);*/
  
      FFmpeg ffmpeg = FFmpeg.getInstance(MainActivity.this.getApplicationContext());
  
      try {
  
          // to execute "ffmpeg -version" command you just need to pass "-version"
  
          ffmpeg.execute(cmd, new ExecuteBinaryResponseHandler() {
  
  
  
              @Override
  
              public void onStart() {}
  
  
  
              @Override
  
              public void onProgress(String message) {}
  
  
  
              @Override
  
              public void onFailure(String message) {}
  
  
  
              @Override
  
              public void onSuccess(String message) {}
  
  
  
              @Override
  
              public void onFinish() {
  
                  stop.setEnabled(false);
  
                  play.setEnabled(true);
  
              }
  
          });
  
      } catch (FFmpegCommandAlreadyRunningException e) {
  
          // Handle if FFmpeg is already running
  
      }
  
  }

  but I am getting following error

  6784-6962/com.flipartstudio.playandrecord E/FFmpeg : Exception while trying to run : [Ljava.lang.String ;@41803270
  java.io.IOException : Error running exec(). Command : [/data/data/com.flipartstudio.playandrecord/files/ffmpeg, /system/bin/ls, -l, /data/data/com.example.foo/files/ffmpeg] Working Directory : null Environment : null
  at java.lang.ProcessManager.exec(ProcessManager.java:211)
  at java.lang.Runtime.exec(Runtime.java:168)
  at java.lang.Runtime.exec(Runtime.java:123)
  at com.github.hiteshsondhi88.libffmpeg.ShellCommand.run(ShellCommand.java:10)
  at com.github.hiteshsondhi88.libffmpeg.FFmpegExecuteAsyncTask.doInBackground(FFmpegExecuteAsyncTask.java:38)
  at com.github.hiteshsondhi88.libffmpeg.FFmpegExecuteAsyncTask.doInBackground(FFmpegExecuteAsyncTask.java:10)
  at android.os.AsyncTask$2.call(AsyncTask.java:287)
  at java.util.concurrent.FutureTask.run(FutureTask.java:234)
  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
  at java.lang.Thread.run(Thread.java:856)
  Caused by : java.io.IOException : No such file or directory
  at java.lang.ProcessManager.exec(Native Method)
  at java.lang.ProcessManager.exec(ProcessManager.java:209)
  at java.lang.Runtime.exec(Runtime.java:168) 
  at java.lang.Runtime.exec(Runtime.java:123) 
  at com.github.hiteshsondhi88.libffmpeg.ShellCommand.run(ShellCommand.java:10) 
  at com.github.hiteshsondhi88.libffmpeg.FFmpegExecuteAsyncTask.doInBackground(FFmpegExecuteAsyncTask.java:38) 
  at com.github.hiteshsondhi88.libffmpeg.FFmpegExecuteAsyncTask.doInBackground(FFmpegExecuteAsyncTask.java:10) 
  at android.os.AsyncTask$2.call(AsyncTask.java:287) 
  at java.util.concurrent.FutureTask.run(FutureTask.java:234) 
  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) 
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) 
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) 
  at java.lang.Thread.run(Thread.java:856) 

  I have also added