3 ms·

Does anyone have any idea why this camera is limited to 1080p30 when playing video? After all, 1080p30 is only 0.5Gbps, and with the CM4's 4 MIPI lanes at 1Gbp

• hatsunearu 5y ago
  >1080p30 is only 0.5Gbps You sure about that? It should be 1920 * 1080 * 3 subpixels * 8 bits * 30 fps = just under 1.5Gbps I assume they use chroma subsampling to make it work
  • michaelt 5y ago
    Yeah, I'm pretty sure. The sensor will have a Bayer pattern [1] and the data will go across the bus in Bayer format. The processor will then perform debayering. So no need to multiply by 3 channels per pixel :) While many image sensors will perform debayering for you if you want, doing so means you need 3x the bandwidth for not much benefit, so very few people do it. [1] https://en.wikipedia.org/wiki/Bayer_filter https://en.wikipedia.org/wiki/Bayer_filter
    • jandrese 5y ago
      So you are working in monochrome? Even after you have applied the Bayer filter you still need 24 bits per pixel do you not?
      • michaelt 5y ago
        No - go check out that Wikipedia link about Bayer filters. For the vast majority of cameras, if you buy a "4 megapixel" image sensor, you get 1 million red pixels, 2 million green pixels, and 1 million blue pixels. When you load the image into your image editor and see 3 colours per pixel, 2 of the 3 are interpolated from neighbouring pixels.