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• avformat/omadec : only compute timestamps based on bitrate if its set

  7 février 2015, par Michael Niedermayer

  avformat/omadec : only compute timestamps based on bitrate if its set
  Fixes division by zero
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavformat/omadec.c

• FFMPEG segment audio stream based on silence

  2 août 2024, par Christian Seyoum

  I have a websocket connection that gets a stream of audio. I am piping the stream to FFMPEG and using it to segemnt the audio in real time. Currenlty the audio does get segemented but all the segemented audio is 10 seconds long rather than being segmented when silence is detected. I am using node.js typescript :

  


  var proc = cp.spawn(ffmpeg, [
      '-f', 's16le',       // Input format: signed 16-bit little-endian PCM
    '-ar', '8000',       // Sample rate: 8000 Hz
    '-ac', '1',          // Audio channels: 1 (mono)
    '-i', '-',  '-af',
      'silencedetect=noise=-18dB:d=0.1', '-f',
      'segment', 
      '-segment_time', '10',
    '-reset_timestamps', '1',
      `${fileNameSubStringPath}_%03d.wav`
    ]);


  


  I have tried changing the silencedetect values and the segment time. But notthing seems to work.

  


  Is there a better way to segment audio based on silence ?

  


• Extracting frame out of video based on time in seconds

  20 avril 2024, par Vicky

  I'm developing a web-based video editing tool where users can pause a video and draw circles or lines on it using canvas. When a user pauses the video, I retrieve the current playback time in seconds using the HTML5 video.currentTime property. I then send this time value along with the shape details to the server. On the server-side, we use FFmpeg to extract the specific paused frame from the video. The issue I'm encountering is a frame mismatch between the one displayed in the browser and the one generated in the backend using FFmpeg.

  


  I've experimented with various approaches for this process.

  


  Extracting frame based on time. Example : in this case time is 3.360 second.

  


  


  ffmpeg -i input.mp4 -ss 00:00:03.360 -frames:v 1 frame.jpg

  


  


  Converting time to frame number using the following logic : Math.round(video.currentTime * fps)

  


  


  ffmpeg -i input.mp4 -vf "select=eq(n,101)" -vsync vfr frame.jpg

  


  


  


  ffmpeg -i input .mp4 -vf "select='lt(t,3.360)lt(3.360-t,1/31.019)',setpts=N/(31.019TB)" -vsync 0 frame.jpg

  


  


  The challenge I'm facing is that sometimes the frame I see in the browser at the pause time doesn't match the one generated in the backend using FFmpeg. How can I solve this problem ? If it's an issue with currentTime, are there any other approaches I can try ?