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• avformat/dhav : Do not evaluate avio_size() multiple times

  6 juin, par Michael Niedermayer

  avformat/dhav : Do not evaluate avio_size() multiple times
  Code like FFMIN(MAX_DURATION_BUFFER_SIZE, avio_size(s->pb)) is not safe
  
  as FFMIN() is a macro and avio_size() is thus evaluated multiple
  
  times
  Reviewed-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/dhav.c

• Reverse video and loop 2 times ffmpeg

  13 septembre 2019, par Shahal

  I need to reverse the input video and concat it then the loop the output video twice.
  I was able to achieve reversing and concat it with original video using

  ffmpeg -i input.mkv -filter_complex "[0:v]reverse,fifo[r];[0:v][r] concat=n=2:v=1 [v]" -map "[v]" output.mkv

  But i want to stream_loop it 3 times. And also i like to know, if there’s any better ways to do it. The video will be a small one(4 seconds max.) and without audio.

• Combining multiple pcm files with different starting times

  18 juillet 2021, par BelMat

  How do I combine multiples pcm files, with different starting times and compress it into wav with ffpmeg.js.

  


  I know I can :

  


  Transform pcm to wav

  


  ffmpeg -f s16le -ac 2 -ar 44.1k -i file.pcm file.wav


  


  Merge files with different starting times :

  


  ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4 -i 4.mp3
  -filter_complex "[2]adelay=10000|10000[s2];[3:a][1:a][s2]amix=3[a]"
  -map 0:v -map "[a]" -c:v copy result.mp4


  


  but how would I combine all of this inside JS, plus getting the files with FS (Node) and the starting time from the file name ?

  


  This is a small snippet where I tried to do all of this :

  


  function MakeAudioFile(){
    const audios = fs.readdirSync('./sound/').filter(file => file.endsWith(".pcm"));
    let result = ffmpeg({
        MEMFS: [],
        arguments: ["-f", "s16le", "-ac", "2", "--ar", "44.1k"],
    });
    audios.forEach(file =>{
        result.arguments.push('-i')
        result.arguments.push(file)
        result.MEMFS.push(fs.readFileSync(`./sound/${file}.pcm`))
    })
}


  


  But didn't get the expected result and had no idea on how to also add the starting time