YUV to RGB Pixel Format

[streampunk]

YUV to RGB Pixel Format

[scriptorian]

Hi,
Thanks for your interest in beamcoder.

My understanding is that vp8 is exclusively an 8-bit 4:2:0 format and it is likely that the FFmpeg vp8 decoder will deliver data as 3 separate buffers for Y, U and V with the U & V buffers each being 1/4 the size of the Y buffer. For the conversion you could look in the Streampunk/nodencl project where you will find a colourMaths.js file in the scratch folder with a function that you could use to generate a set of matrix coefficients and a matrixMultiply function that would do the right thing on YUV source data if you are not too worried about the knotty details of white points and gamma functions.

However I think an easier way to progress this could be to use a bit more of beamcoder to do the conversion for you. Using the streaming helpers that would be something like the below, with scale, spec, colorspace etc values set as you require:

async function run() {
  const urls = [ 'file:/Users/ianrothmann/Downloads/RT76057bde97adbd0537bcdb89037c9034.mkv' ];
  const spec = { start: 0, end: 10 };

  const params = {
    video: [
      {
        sources: [
          { url: urls[0], ms: spec, streamIndex: 0 }
        ],
        filterSpec: '[in0:v] scale=1280:720, colorspace=all=bt709 [out0:v]',
        streams: [
          { name: 'rawvideo', time_base: [1, 90000],
            codecpar: {
              width: 1280, height: 720, format: 'rgb24', color_space: 'bt709',
              sample_aspect_ratio: [1, 1]
            }
          }
        ]
      }
    ],
    out: {
      formatName: 'rawvideo',
      url: 'file:temp.raw'
    }
  };

  await beamcoder.makeSources(params);
  const beamStreams = await beamcoder.makeStreams(params);

  await beamStreams.run();
}

console.log('Running');
let start = Date.now();
run()
  .then(() => console.log(`Finished ${Date.now() - start}ms`))
  .catch(console.error);

I hope this helps!