Question / Help Lossless nvenc capture of Replay Buffer

[Chetyre]

Hello everyone. I'm new to this program, and I was hoping you could help me with some issues I'm having.

I want to be able to use this as a substitute to shadowplay (because i don't like geforce experience), and I heard OBS could record from the buffer to a file. So I downloaded it and did some tests.

Since I have a buttload of memory, I wanted to capture it using the lossless profile and edit anything of interest later. I set it to record the last 10 minutes. All my hotkeys are functioning properly, and file is saving properly. I seem to be able to play normaly without running out of memory.

My problem, however, is that the capture has a lot of artifacts. It is very blocky both during moving and non-moving scenes. Am I doing something wrong, or is lossless capture simply not working properly?

My settings are as follow:

Encoder: Nvidia NVENC
Use CBR unchecked
Quality Balance 0 (I don't really understand this one or if it does anything with the lossless profile)
Max Bitrate 70000 (not sure if it does anything with CBR unchecked)
Use Custom Buffer Size unchecked

in advanced:

NVENC Preset: Lossless
Encoding Profile: high
Keyframe Interval: 0
Use CFR checked
Encode in Full Range checked.


Thanks in advance.

EDIT: Uploaded a log file.

 

[Boildown]

I don't think the NVEnc Lossless preset actually works. Try the High Quality preset instead. Use a custom buffer and set it to 0. Quality Balance is only used for x264 encoding.

 

[Chetyre]

Thanks Boildown. I switched to High Quality with CBR 60000 and it looks acceptable. A silly question though: what does custom buffer actually do? I couldn't figure it out.

Also, colors seem to be too bright. Is there a gamma setting I'm missing?

 

[Boildown]

A default sized buffer is one with its size equal to the bitrate of the stream (30,000 kb/s bitrate would mean a 30,000 kb buffer). A custom buffer is one where you set the value of the buffer manually instead of accepting the default size.

Setting the buffer to 0 has a different effect. According to R1CH, one of the OBS developers, "Setting the buffer size to zero disables the VBV system, allowing x264 to hit any bitrate necessary to achieve the quality (CRF) specified." I think this is the highest quality way to record to disk. Its not good for streaming though, streaming needs a much more consistent bitrate.

I'm not aware of a gamma system. You're sure you didn't set your monitor to be really dim with a high in-game brightness? Something like that could account for it.

 

[FerretBomb]

If you're using NVENC, you want a matched bitrate and buffer.

Only x264 unlocks the bitrate to 'use whatever is needed' mode with a zero-buffer, NVENC doesn't and apparently causes issues if it's set to that.

 

[Boildown]

If you're using NVENC, you want a matched bitrate and buffer.

Only x264 unlocks the bitrate to 'use whatever is needed' mode with a zero-buffer, NVENC doesn't and apparently causes issues if it's set to that.

That's news to me. Pretty sure I've been doing it this way for a long time. But I don't always watch my NVEnc recordings until I go to make a video. What sort of issues are you aware of?