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• ffpmeg - how to detect if video crop is completed ?

  30 septembre 2021, par Radespy

  Thanks in advance.

  


  I'm trying to crop a .mp4 video using an ffmpeg binary (within the context of an electron-react-app).

  


  (The binary is run in a child process using execFile() and outputs to a temp folder which is later deleted)

  


  ffmpeg varies considerably in the time it takes to complete the creation of a cropped video file (1sec to 18sec) depending on the computer (mac vs Windows).

  


  I need to read the cropped video file.

  


  I've set up an event listener in the Main process of electron

  


  
if (!monitorCroppedFile) {
        console.log(`${croppedFilePath} doesn't exist`);
      } else {
        console.log(`${croppedFilePath} exists !`)
        ...readFile...;


  


  Once monitorCroppedFile = true I read it using fs.readfile().

  


  The problem is that ffmpeg initally creates the cropped file path but it sometimes takes ages to complete the process of cropping.

  


  This results in the read file often being blank (as the read is triggered on detecting the file path of the cropped file).

  


  I've tried using -preset ultrafast in the ffmpeg arguments but this only improves things on Windows marginally.

  


  The problem doesn't occur on Macs.

  


  Can anybody suggest a possible solution ? Is there a way to detect when the crop is fully completed ?

  


  Many thanks.

  


• Issue with creating Video files from Binary files

  22 septembre 2022, par user20057686

  We have a bunch of binary files that represent Video data.
This is how the binary files were created :

  


  

  1. Used MediaRecorder from a React application to capture the browser window.
To capture the screen stream we used (Navigator.)MediaDevices.getDisplayMedia() API

  


  2. Each video is recorded for 1-second duration

  


  3. This data is then encoded with base64 and sent through a websocket. The server decodes the base64 string and stores the binary data in a file (without any extension)

  


  


  So we now have a bunch of binary files each containing 1 second worth of video data.

  


  The issue is, we are not able to convert all the binary files back to a single video.

  


  


  1. We tried using ffmpeg

     


     copy /b * merged.

     


     ffmpeg -i merged merged.mp4

     


  


  


  Basically first merging all the binary files and converting to mp4. It didn't work. The resulting video duration is not equal to the (number_of_files) in seconds.

  


  


  2. We also tried converting individual chunks with ffmpeg but we get the below error :

     


     [h264 @ 000001522dc74b80] [error] non-existing PPS 0 referenced
[h264 @ 000001522dc74b80] [error] non-existing PPS 0 referenced
[h264 @ 000001522dc74b80] [error] decode_slice_header error
[h264 @ 000001522dc74b80] [error] no frame !
I can provide the complete logs if needed.

     


  


  3. Next thing we tried was to use MoviePy library in Python. We programmatically concatenated the files and saved them as WebM and imported it into MoviePy as a Video.

     


  


  


  In all the above approaches, we couldn't get the full video.

  


• Range input breaks ffmpeg when seeking in Chromium

  14 janvier, par Tania Rascia

  I'm getting the following error erratically when I seek with the range input in a React app, which renders the input unusable until refresh :

  


  PIPELINE_ERROR_READ: FFmpegDemuxer: demuxer seek failed

  


  The only occurrence of this error I can find online is in the Chromium source code. <— linked file goes directly to the line where the error exists.

  &#xA;

  I can't replicate the error in Firefox.

  &#xA;

  


  &#xA;

  Nothing out of the ordinary is going on with the input.

  &#xA;

  const handleScrub = (event) => {
  const newTime = event.target.valueAsNumber

  setProgress(newTime)
  audioRef.current.currentTime = newTime
}


  &#xA;

  It happens if you click around really fast on the range. Here is an example of the source code, but the error doesn't happen with an .ogg file, only a signed .flac file.

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