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• FFmpeg - How do I set audio language and subtitles when converting videos ?

  7 mai 2022, par mereMolf

  I have a handful of mkv video files that happen to have English and Japanese audio tracks along with english subtitles. I want to convert them all to webm files and keep only the Japanese audio with English subtitles.

  


  How do I do that ?

  


  Specifically, I use QWinFF, a GUI frontend to FFmpeg.
Under the Advanced options, I use the following parameters

  


  -f webm -vcodec libvpx -g 120 -level 216 -profile:v 0 -qmax 25 -qmin 10 -rc_buf_aggressivity 0.95 -vb 480k -acodec libvorbis -aq 90


  


  Any help would be appreciated.
Thanks.

  


• Stream map '0:a:0' matches no streams

  6 décembre 2019, par Сергей Барахтенко

  To encode a video using FFMPEG the following command is used :

  /usr/bin/ffmpeg -i INPUT.MP4 
  
  -preset veryfast -r 25 -g 75 -threads 4 -sc_threshold 0 
  
  -map 0:v:0 -map 0:a:0 
  
  -filter:v:0 scale=h=240:w=-2  
  
  -minrate:v:0 75k  
  
  -maxrate:v:0 218k  
  
  -bufsize:v:0 300k 
  
  -b:v:0 150k  -c:a aac -b:a 128k -ac 2 
  
  -var_stream_map "v:0,a:0" 
  
  -master_pl_name master.m3u8 
  
  -f hls -hls_time 3 -segment_time 6 
  
  -hls_list_size 0 -segment_format mpegts 
  
  -hls_segment_filename /res-%v/segment-%d.ts  OUTPUT.M3U8  1> log.txt 2>&1 

  In general, despite such a huge command, it copes with the task with a bang

  But there is one little BUT :

  If you run this command on a video WITHOUT audio, there will be an error :

  Stream map '0:a:0' matches no streams. To ignore this, add a trailing '?' to the map.

  Yes, I understand that the command tells me that the audio stream was not found. And to ignore this, you need to add a trailing question mark to the map

  But only I can’t understand where ? to which place ?

  I will be glad to any advice or suggestion

  Thanks in advance

• make webbased ffmpeg-live transcoder on linux for multiple streams

  11 juillet 2017, par Dlniya Dlzar

  Hi I am planning to make webbased ffmpeg-live transcoder on linux for multiple streams .
  Using ffmpeg and ngnix-rtmp is the basic that i found and planning to do it
  my plan is (Web interface for adding and modifying streams (name ,input,output..)
  in database , database i mean (json file). and execute ffmpeg command depend on the JSON file (now one more thing i want to do , is to monitor streams based on
  nginx-rtmp-module/stat.xsl
  git https://github.com/arut/nginx-rtmp-module/blob/master/stat.xsl
  and restart streams if there is problem , like no audio or picture
  whats is best structure to do it ?? which language is good to do the proccess
  is there any missing knowledges ?? is there any other better way in your mind ??