Why does Canon 600D/T3i video quality drop dramatically once it's recorded — in comparison to what I see in Live-View w/ Digital Zoom?

Question

I have a low-light situation with a lot of small details and diagonal lines. When I look at the scene with digital zoom in Live View mode I see some grain but I see all the details and can clearly read the small print. Once I record the same scene in 1080p (I also tried to increase the bitrate with ML firmware) everything gets blurry, aberrations pop up (green/blue flickering edges), lines get broken, and it looks like upscaled 480p. Why does this quality drop happens and is there a way to minimize it if not get rid of it?

Answer 1

This has to do with Data Rate. T3i does not utilize a high resolution data rate codec. Meaning that you can see it, but the camera will only compress at the quality level available to itself from its designated codecs. Codecs meaning software compression. If you were to use for example a Sony A6000 in its XAVC-S setting. It would give a HUGE FILE! But the image would be almost identical to what you see. Usually it shows more in palyback than what you actually see on the screen.