Constant QP rendering- setting the quantization parameter

gmr wrote on 3/24/2018, 12:24 PM

I see that the Magix/NVENC encoder has a setting for Constant QP as its rate control, which is great. However, the default quantization parameter seems to be set a little high, and I can't see any way to adjust it. I was guessing that maybe the VBR drop-downs were doing double duty, but that doesn't seem to be the case. Is there a place I can adjust the parameter to get a higher quality render?

Comments

Musicvid wrote on 3/26/2018, 10:24 PM

Full user control over nvenc paarameters can be found in ffmpeg.

There are some very good reasons not to include them in a consumer product, because 99% will do something really silly and then blame the software. In the case of QP, the Q factor may have been optimized to mask the intrinsic damage done by hardware encoding.

gmr wrote on 3/26/2018, 10:50 PM

I think we're talking past each other- I'd like to set a lower parameter, which is higher quality...I haven't bothered to make some short comparison renders, but it looks like it's in the low-mid 20's, and I can see the hardware-encoder blockiness at whatever it's set at. I like using around 18, which is when it gets about visually indistinguishable for what I use.

Musicvid wrote on 3/27/2018, 3:32 AM

Yes, I didn't know those numbers worked the same as cq/crf in x264/x265, with which I am abundantly familiar.

Ffmpeg is a free download and exposes all the internal settings I understand, so you should be able to play to your heart's content. Handbrake supports Intel qsv, but not nvenc yet because their coders are volunteers working on their own time.

Musicvid wrote on 3/27/2018, 8:19 AM

Didn't take much digging to find this. It is looking more likely to make it's way into Vegas Pro, since Studio's marketing presence more or less appeals to kids, soccer moms, and the occasional hobbyist.

https://developer.nvidia.com/nvidia-video-codec-sdk

If you would reframe your question as an advanced feature request for Vegas Pro, I bet someone from Magix would take notice and reply.