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I am trying to write a program that takes a video of someone's face, extracts the RGB values, and then uses the color change (imperceptible to the human eye) to map onto heart rate. When I use a logitech C270 HD WEBCAM recording .avi video files, my program works really well because the RGB data is very rich with little noise.

When I switch to using my macbook webcam or an iphone/ipad camera, the RGB data looses its richness and becomes more noisy (lower signal to noise ratio). Why is this? I would think apple cameras would be similar or better quality than the $40 logitech.

The biggest difference I see is that the logitech .avi files run 184410 kb/s and the mac .mov or .mp4 files are ~7000 kb/s.

I know for sure the logitech files are uncompressed. I'm pretty sure that the apple mov or mp4 files are uncompressed (I didn't do any compressing, but maybe its done automatically on the device?).

Any ideas how I can get my mac or iphone/pad to match the quality (interms of kb/s) of the logitech?

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  • If they're mp4s they're compressed, probably with h.264. Pretty unlikely that the logitech is uncompressed too—720p uncompressed video data rate is ≈500mb/s. So both compressed, but the difference as you said is the data rate. Also this: tidbits.com/2020/04/08/…
    – stib
    Feb 17, 2021 at 23:29
  • Thanks, this is helpful. I see that all mp4's are compressed. Is it possible to record uncompressed or > 150000 kb/S video on any smartphone or tablet? edit: this seems like a separate issue, will start new post.
    – connor449
    Feb 18, 2021 at 16:30

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