Nothing compares to ffmpeg. It's the industry leader and lots of software (including all stream software if I'm not mistaken) use ffmpeg in some way. I don't think Kumari supports RGB formats, so you'll always get the big quality loss that comes from YUV420. Although you do need YUV420 to submit HQ/MQ/LQ to SDA, it's better to have pure lossless recordings with a native pixel format so you can get better encodings after the fact, as well as submit IQ or XQ videos with RGB. You can always encode to YUV420 from an RGB recording.
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