Author Topic: Option to set Q-Scale Max and Min values for CBR  (Read 2678 times)


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Option to set Q-Scale Max and Min values for CBR
« on: August 01, 2012, 02:16:33 PM »
CBR is much safer than Q-Scale, however it sometimes uses very high quality Q-scales on scenes that don't require it.  For example, for casual home/holiday movies I may decide I don't ever want to go better than Q-scale -8 or -4.  (For clarity, negative Q-scales are less compressed and higher quality than positive ones.)  This would save space on the card and also on my HDD later (and forever), and increase the 4GB recording time limit.

Of course, the CBR setting can be reduced, e.g. to 0.6x, but this will result in noticeably poor quality in complex scenes.  An obvious approach would be to use the specific Q-scale value all the time, but the option of the proposed Q-scale-limited CBR would avoid the dangers of suddenly stopping recording if Q-scale -8 Is used all the time.

Yesterday I briefly tested Q-scale -8 on a stationary scene, just moving the camera side to slide and it choked several times, despite using a just-formatted 45MB/s (300x) SanDisk UHS-1 SD card.  (Which, for clarity, is 4.5x faster than a Class 10 card.)

This could also be useful for people with class 4 or class 6 cards, because CBR 1.0 limited to Q-scale -8 may work much more safely.