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• OpenCV write jpeg buffer into Popen object

  5 novembre 2017, par M Leonard

  I am doing some image operations on a numpy array via OpenCV. These images are then being baked out to jpeg, then ingested into FFMPEG to make a video. However, baking it out to a file is not very efficient. I would like to stream this directly into FFMPEG. In theory, it would look something like this :

  p = Popen(['/usr/local/bin/ffmpeg', '-s', '1920x1080',
  
                     '-pix_fmt', 'yuvj420p',
  
                     '-y',
  
                     '-f', 'image2pipe',
  
                     '-vcodec', 'mjpeg',
  
                     '-r', self.fps,
  
                     '-i', '-',
  
                     '-r', self.fps,
  
                     '-f', 'mp4',
  
                     '-vcodec', 'libx264',
  
                     '-preset', 'fast',
  
                     # '-crf', '26',
  
                     'output/{}.mp4'.format(self.animation_name)], stdin=PIPE)
  
  
  
  image_resize = cv.resize(self.original_image, (0, 0), fx=zoom, fy=zoom)
  
  M = np.float32([[1, 0, x_total], [0, 1, y_total]])
  
  image_offset = cv.warpAffine(image_resize, M, (self.original_image_width, self.original_image_width))
  
  image = image_offset[0:self.output_raster_height, 0:self.output_raster_width].copy()    
  
  cv.imwrite(p.stdin, image) # this doesn't actually work, but that's the idea...

  I’ve been able to achieve this with Pillow using this setup :

  p = Popen(['/usr/local/bin/ffmpeg', '-s', '1920x1080',
  
                     '-pix_fmt', 'yuvj420p',
  
                     '-y',
  
                     '-f', 'image2pipe',
  
                     '-vcodec', 'mjpeg',
  
                     '-r', self.fps,
  
                     '-i', '-',
  
                     '-r', self.fps,
  
                     '-f', 'mp4',
  
                     '-vcodec', 'libx264',
  
                     '-preset', 'fast',
  
                     # '-crf', '26',
  
                     'output/{}.mp4'.format(self.animation_name)], stdin=PIPE)
  
  
  
  image_resize = self.original_image.resize((resize_width, resize_height), resample=PIL.Image.BICUBIC)
  
  image_offset = ImageChops.offset(image_resize, xoffset=int(x_total), yoffset=int(y_total))
  
  image = image_offset.crop((0, 0, self.output_raster_width, self.output_raster_height))
  
  
  
  image.save(p.stdin, 'JPEG')

  So, my question is :

  How would I write an OpenCV Jpeg buffer into the p.stdin object like it’s being done in the Pillow version ?

• Sending Blobs from a Chrome Extension to a Node.js Process without WebSockets [closed]

  29 octobre 2023, par Matrix 404

  Question :
I have a Puppeteer script that runs a Chrome extension, which opens a webpage. The extension records that tab and sends the recorded blobs to the main Node.js process using WebSockets. The main process then streams these blobs to an RTMP server.

  


  I'm looking for an alternative method to send blobs to the main process without using WebSockets. Additionally, I want to know if it's possible to stream these blobs directly from the browser using FFmpeg wasm.

  


  Details :

  


  


  1. My current setup : Puppeteer script -> Chrome extension (recording) -> WebSockets -> Node.js process -> RTMP server.

     


  


  2. I'm exploring options to eliminate the use of WebSockets while maintaining the ability to send recorded blobs from the Chrome extension to the Node.js process efficiently.

     


  


  3. Is it possible to use FFmpeg wasm to stream blobs directly from the browser to an RTMP server ? If so, how can this be achieved ?

     


  


  


  Additional Information :

  


  

  • The technology stack I'm using includes Puppeteer, Chrome extension, Node.js, and FFmpeg.

  


  • Any code snippets, examples, or recommended libraries are greatly appreciated.

  


  


  Constraints :

  


  

  • Compatibility with modern browsers and reasonable performance are essential.

  


  • Ideally, the solution should work in a headless Chrome instance.

  


  


  Thank you for your assistance in finding an efficient solution to this problem !

  


  

  • The technology stack I'm using includes Puppeteer, Chrome extension, Node.js, and FFmpeg.

  


  • Any code snippets, examples, or recommended libraries are greatly appreciated.

  


  


• dnxhd : interleave AC levels and flags

  14 octobre 2015, par Christophe Gisquet

  dnxhd : interleave AC levels and flags
  This allows more efficient access to the array as the level and flags
  
  are contiguous. Around 4% faster coefficient decoding.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/dnxhddata.c
  • [DH] libavcodec/dnxhddata.h
  • [DH] libavcodec/dnxhddec.c
  • [DH] libavcodec/dnxhdenc.c