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• avformat/gifdec : switch to using gif parser

  20 mai 2023, par Paul B Mahol

  avformat/gifdec : switch to using gif parser
  Update fate test, more correct as last packet is not truncated.
  

  • [DH] libavcodec/gifdec.c
  • [DH] libavformat/gifdec.c
  • [DH] tests/ref/fate/gif-demux

• ffmpeg moving text but only within Y limits

  28 décembre 2022, par Yoav Mor

  I need to add text to a video that will scroll from bottom to top ; I managed to do it with something similar to this :

  


  ffmpeg -i vid.mp4 -vf "drawtext=fontfile=tahoma.ttf:fontsize=20:fontcolor=green:x=(w-text_w)/2+20:y=if(lt(t\,2)\,480\,(h-400-(40*t))):textfile=scroll.txt:bordercolor=white:borderw=1" -c:v libx264 -y -preset ultrafast scrolling.mp4

  


  The original video is 960x540, so the text starts at position y=480 and, after 2 seconds, starts moving up.
That bit works fine, and the text "vanishes" at the top of the frame as it scrolls up.
What I need to achieve is for the text to scroll only within certain Y limits, imagine a virtual box around the text, so it scrolls up only from a certain Y position in the bottom (but not the very bottom) and disappears into a line on the top that isn't the top part of the frame.
Can that be achieved with ffmpeg ?

  


  EDIT : Maybe the trick here should be to put the text on top of a transparent video that's smaller in height, and then within the same command somehow merge this new video that has the text with the original video. Not sure how achieve that though.

  


• 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