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• Sending 2 streams to FFmpeg from nodejs

  18 août 2019, par Sylens

  I am trying to send 2 ReadableStreams to FFmpeg from nodejs. I have tried using fluent-ffmpeg library to do this, but it only supports sending one stream for processing. Check here

  My problem is :
  I have 2 incoming mono audio streams, I want to send them to ffmpeg to create a stereo stream, which I will then send to google’s speech to text service, to generate a transcription.

  I am successfully receiving both the mono streams to the nodejs server.
  How to utilize FFmpeg to merge them in realtime is still unclear, I could spawn a FFmpeg child process, but I’m not sure how to give 2 ReadableStreams as inputs and get the output as another stream ? FFmpeg supports multiple input streams.

  I can merge the 2 mono streams if they are in two separate files with this code.

  const { spawn } = childProcess;
  
  const ffmpeg = spawn('ffmpeg', [
  
    '-i', this.phoneAudioFile,
  
    '-i', this.micAudioFile,
  
    '-filter_complex', '[0:a][1:a]amerge=inputs=2[a]',
  
    '-map', '[a]',
  
    this.outputLosslessFile,
  
  ]);

  How can I acheive the same using 2 streams instead of 2 files ?

  EDIT

  • The incoming streams both have PCM audio data.
  • This entire process runs on a linux Ubuntu server.
  • The final output must be a wav file.

• FFMPEG- how to set presentation timestamp of a second video while merging a second video side-by-side with a first video

  14 octobre 2020, par Sankalpa Sarkar

  I was trying to merge a second video into a first video, side-by-side in a stacked fashion as a self-interest work. The twist is the video is a recording of a video call, where a second user might join at a later stage than the first user. The cumulative recording of the video call must reflect that the second user joins at a later stage than the first user. For this, I am using this code :

  


  DIFF=$(($start_ts-$BASEts))
DIFFms=`echo "scale=0;$DIFF/1000" | bc`
DIFFs=`echo "scale=4;$DIFF/1000000" | bc`
ffmpeg -i $a.webm -i b.webm -filter_complex \
    "[0]pad=2*iw:1*ih[l];[1]setpts=PTS-STARTPTS+$DIFFs/TB[1v]; [l][1v]overlay=x=W/2[v]; \
    [1]adelay=$DIFFms|$DIFFms[1a]; \
    [0][1a]amix=inputs=2[a]" \
    -map "[v]" -map "[a]" -vcodec libvpx -cpu-used -5 -deadline realtime finalOutput.webm


  


  However, the error being thrown here is :

  


  [Parsed_setpts_1 @ 0x55ada9df1dc0] [Eval @ 0x7ffff35acb60] Undefined constant or missing '(' in '/TB'
[Parsed_setpts_1 @ 0x55ada9df1dc0] Error while parsing expression 'PTS-STARTPTS+/TB'
[AVFilterGraph @ 0x55ada9d6c2a0] Error initializing filter 'setpts' with args 'PTS-STARTPTS+/TB'
Error initializing complex filters.
Invalid argument


  


  It is unable to read the $DIFFs variable at all, is what I figured. Can anybody help me out here ?

  


• Combine .dash video and audio segments to .mp4

  11 décembre 2019, par Mike Stevens

  I was able to download some dash video segments (youtube-dl was apparently blocked from downloading the .mpd and just downloading, concatenating as normal) and was hoping to combine/concatenate them so I could watch in VLC, perhaps using ffmpeg. I was able to download the relevant .mpd and .ismc files, so I have all of the DASH video and audio segments, as well as the .mpd and .ismc downloaded and in one folder.

  The video files are labelled as such

  video=869000.dash
  
  video=869000-0.dash
  
  video=869000-600.dash
  
  video=869000-1200.dash

  and the audio in a similar fashion

  audio=96000.dash
  
  audio=96000-0.dash
  
  audio=96000-96225.dash

  Would anyone know of a way to combine all of these into one watchable video file ? AdobeHDS used to work great for combining fragments, and youtube-dl cleary has some sort of method to do it, but neither works with this particular .mpd. I don’t believe concatenate in ffmpeg will work, when I try to do that, it initializes the first .dash file (audio or video), but stops there.

  When I try to put the .mpd file through ffmpeg, it returns "Failed to open an initialization section in playlist 0". I would’ve assumed this initialization was the video=869000.dash file though (which is the one segment file that ffmpeg does recognize) ?