h264 bitrate in jit.record

karl krach's icon

since i could not find anything in the documentation: is there any way to adjust the bitrate for h264 encoding when using jit.record (viddll engine)?

thanks for any help!
k

ps. also, what seems weird: when switching to avf engine the same files get much smaller then with viddll (5 min of h264 1280x720@12fps: 775mb with viddll vs. 144mb with avf).

Rob Ramirez's icon

jit.grab helpfile --> VIDDLL Specific --> p dictionary options

let me know if that doesn't get you sorted

karl krach's icon

ah... well hidden... found it, thanks!

two questions left: these numbers are bit or byte per second? would "4000k" result in 4mbit/s = 0.5mbyte/s?

and: is this the maximum bitrate? i'm asking since the files i get vary in size but are usually way smaller then what i would expect. is there also the chance to set a target or minimum bitrate?

k

karl krach's icon

for reference: the bitrate setting ("set b") produces rather odd results but one can also specify max/min bitrates ("set maxrate" or "set minrate") to get more control. in most cases though, the better option is using crf (constant rate factor), which produces better results: eg. "set crf 17", more info here: https://trac.ffmpeg.org/wiki/Encode/H.264