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• ffmpeg inside chrome extansion

  16 août 2021, par Denis Dombrovski

  hello I am trying to use the ffmpegwasm/ffmpeg.wasm library inside chrome extension
the library is loaded inside react component that is located inside an iframe

  


  the problem is when I try to load I got an error that I cannot download the core files

  


  I tried to use the example library for chrome extension but also got an error "Uncaught (in promise) ReferenceError : SharedArrayBuffer is not defined error. "

  


  the files are web_accessible_resources inside the manifest

  


  I am using manifest version 3

  


• How to write mp4 video file with H264 codec ?

  21 mai 2017, par kramer65

  On OSX I can record from my webcam and write a video file with the following simple script :

  import cv2
  
  camera = cv2.VideoCapture(0)
  
  
  
  # Define the codec and create VideoWriter object to save the video
  
  fourcc = cv2.VideoWriter_fourcc(*'XVID')
  
  video_writer = cv2.VideoWriter('output.avi', fourcc, 25.0, (640, 480))
  
  
  
  while True:
  
      try:
  
          (grabbed, frame) = camera.read()  # grab the current frame
  
          frame = cv2.resize(frame, (640, 480))  # resize the frame
  
          video_writer.write(frame)  # Write the video to the file system
  
  
  
      except KeyboardInterrupt:
  
          camera.release()
  
          break

  The resulting avi file is quite big though. I want a smaller file, preferably an mp4. So I changed the filename to output.mp4 and the fourcc codec to H264. That writes a video file which works, but gives me the following error :

  $ python write_video_file.py 
  
  OpenCV: FFMPEG: tag 0x34363248/'H264' is not supported with codec id 28 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x00000021/'!???'

  Since I thought I’m missing the H264 codec in ffmpeg I decided to uninstall ffmpeg and opencv and reinstall them again with H264 support. For this I used the following commands :

  # First ffmpeg
  
  brew install ffmpeg --with-fdk-aac --with-libvidstab --with-openh264 \
  
        --with-openjpeg  --with-openssl --with-tools --with-webp --with-x265 --with-zeromq
  
  # then opencv3
  
  brew tap homebrew/science
  
  brew install opencv3 --with-contrib --with-ffmpeg --with-tbb

  After this I ran the script again, using the following combinations :

  • output.mp4 with H264
  • output.mp4 with X264

  Unfortunately I still get the OpenCV warnings/errors. The file is readable, but it still annoys me that I get these errors. Does anybody have any idea how I can make OpenCV write mp4 video file with the H264 codec ?

  All tips are welcome !

• How to write mp4 video file with H264 codec ?

  20 octobre 2017, par kramer65

  On OSX I can record from my webcam and write a video file with the following simple script :

  import cv2
  
  camera = cv2.VideoCapture(0)
  
  
  
  # Define the codec and create VideoWriter object to save the video
  
  fourcc = cv2.VideoWriter_fourcc(*'XVID')
  
  video_writer = cv2.VideoWriter('output.avi', fourcc, 25.0, (640, 480))
  
  
  
  while True:
  
      try:
  
          (grabbed, frame) = camera.read()  # grab the current frame
  
          frame = cv2.resize(frame, (640, 480))  # resize the frame
  
          video_writer.write(frame)  # Write the video to the file system
  
  
  
      except KeyboardInterrupt:
  
          camera.release()
  
          break

  The resulting avi file is quite big though. I want a smaller file, preferably an mp4. So I changed the filename to output.mp4 and the fourcc codec to H264. That writes a video file which works, but gives me the following error :

  $ python write_video_file.py 
  
  OpenCV: FFMPEG: tag 0x34363248/'H264' is not supported with codec id 28 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x00000021/'!???'

  Since I thought I’m missing the H264 codec in ffmpeg I decided to uninstall ffmpeg and opencv and reinstall them again with H264 support. For this I used the following commands :

  # First ffmpeg
  
  brew install ffmpeg --with-fdk-aac --with-libvidstab --with-openh264 \
  
        --with-openjpeg  --with-openssl --with-tools --with-webp --with-x265 --with-zeromq
  
  # then opencv3
  
  brew tap homebrew/science
  
  brew install opencv3 --with-contrib --with-ffmpeg --with-tbb

  After this I ran the script again, using the following combinations :

  • output.mp4 with H264
  • output.mp4 with X264

  Unfortunately I still get the OpenCV warnings/errors. The file is readable, but it still annoys me that I get these errors. Does anybody have any idea how I can make OpenCV write mp4 video file with the H264 codec ?

  All tips are welcome !