In and attempt to make my recordings more digestible for video editors I'm trying to re-encode my files to DNxHR, after a few hiccups I got solid output with this command:
ffmpeg -ss 00:08:20 -i \\ASEXYCAPTUREPC\Users\djcim\Videos\Main\Magewell\Mage00.ts -map 0 -c:v dnxhd `
-profile:v dnxhr_hq -b:v 250M -acodec copy -ss 00:00:10 -t 00:00:20 `
S:\Videos\SavedClips\COD\Magewell\Test_Mage.mov
However it doesn't seem like it's taking my specified bitrate, when I probe the file with ffprobe:
ffprobe -i [input file] -show_streams
it says bit_rate=1739980800 which comes out to 1700M if I'm not misaken, far above the 250M I want.
Not sure if this is the only factor but the result is huge files, around 12GB a minute while the source file itself is 10 minutes long but only 15GB.
The source file is also encoded / recorded using FFmpeg and has a resolution / frame rate of 3440x1440 @ 100FPS with a 250MB bitrate.
Any ideas? Really hoping to get these files much smaller.
The DNx encoders don't accept bespoke ratecontrol. The quantization parameters are fixed. Output bitrate is a function of frame size, framerate and pixel format.