T3i and Magic Lantern Bitrate

[NorBro]

So I have seen some posts about using ML to boost the bit rate, but I hear talks about qscale or something?

In the newest version of ML, you can choose numbers....From .1x - 3.0x.

1.0x is the default. I have had success recording up to 2.3x with a Class 10 SDHC. Anything after that stops recording because the card isn't fast enough.

Regardless, what do you guys think about this? Does it really work? And how does it work?

I did notice that the files recorded at 2.0x were up to 70 Mbits/s.

Thoughts?

Thank you.

 

[M. Gilden]

The benefit of adjusting the bitrate is arguable. The sensor and encoder can only resolve a limited amount of data, and the default bitrate doesn't seem to be a bottleneck.

Turning up the bitrate results in larger files, but not necessarily a clearer picture.

 

[c3hammer]

I don't think it's arguable

It doesn't do anything to image quality IMHO. I've tested it a bunch up to about 100mbps and no matter how I look at, edit, grade or zoom into the image I can't find any perceptable difference. The files are huge for sure, but side by side testing with motion and heavy grading show ZERO improvement in my experience.

It appears that the way Canon lines skips and goes to H.264 takes place before the increase in bit rate and thus provides very little to no benifit.

Cheers,
Pete

 

[M. Gilden]

The Qscale value is useful, however, in the opposite direction. The question is how LOW can you set it before you can notice a decrease in image quality.
Smaller file sizes means longer shooting time (in case the 12-15 min limit to 4GB is too shot for you) as well as more space on the card.