What is replay buffer?
Replay Buffer
Replay buffer allows you to save the last X seconds of Video and Audio to your disk on the press of a button.
This functions very similarly to NVDIA's Shadowplay and AMD's ReLive, and other programs that have a replay feature.
The main advantage of using Replay Buffer over these other alternatives is that Replay Buffer uses RAM as a temp storage. It does this rather than constantly writing to a drive (typically the temp folder in C:), which can burn up SSD writes.
Follow the instructions to install OBS Studio.
Here we'll go through all the settings necessary for both general recording and replay buffer.
First, start with the Recording tab, we'll be skipping over the Stream tab for this tutorial.
Leave Type on Standard.
Set Recording Path to somewhere.
Set Recoding Format to mp4, if you use multiple audio tracks (recommended). You can use MKV, but I wouldn't recommend OBS's built in remux function. Look into FFMPEG for remuxing.
Skip Audio Track for now, we'll return to this.
This gets a little complicated. Refer to Differences in Encoders.
DO NOT SET RESCALE OUTPUT HERE. THIS CAN FUCK YOU UP. DON'T DO IT.
For Rate Control, select CQP and set it to 20-21 (Lower = better quality). This results in large file size, but superb quality. Refer to Rate Control for the other options.
Preset should be set to either Max Quality or Low-latency Quality, whichever gives you the best results.
Profile should be set to high, but if you have issues use main. (High decodes better, but encoding can be worse sometimes).
GPU should be always 0, unless you have a spare GPU, but even then its typically not worth doing. Explanation
Leave B-Frames on 2, you generally shouldn't touch this unless you REALLY know what you're doing.
Now, on the Audio tab, set all the tracks to be 160 for their bitrate.
As for the Replay Buffer tab, check the box for enabling it.
Set Maximum Memory from 1GB (1024MB) to 4GB (4096) depending on how long your buffer is, and your rate control.
As for the Audio section in settings, there is very little to configure here.
Set Devices as necessary, disable devices you do not actively use.
Everything else is fine as default.
Now in the Video category in settings, there's only a few options but they are the most important.
Output (Scaled) Resolution should be set to your native res.
Downscale Filter can be anything, since we aren't descaling. For performance reasons, set this to bicubic.
In order to use Replay Buffer, there's only one option that is necessary here.
You can set hotkeys for Start Replay Buffer and Stop Replay Buffer, but they are unnecessary as you can start and stop it from the UI.
Once you have the Scene selected you want to record, simply start the replay buffer with the Start Replay Buffer button in the bottom right of the main UI.
You can stop the replay buffer with the Stop Replay Buffer button once it is active.
Press the Save Replay hotkey anytime you want to save your buffer of Maximum Replay Time.
There are 5 options for encoding, some might not be available to you.
- AMD VCE Encoders
- Intel QuickSync
- Nvidia NVENC
- Nvidia NVENC (New)
- x264
NVIDIA cards might have two options, or just one.
If your card is 1000 series or below, you'll want to stick to the old encoder, I found issues with encoding on new on a 1080.
If you have a 2000 series card, the new encoder will be your new best friend. Only use old if you have to.
For AMD make sure you have the AMD OBS plugin (may not be included).
Intel integrated chips can try to use QuickSync.
If no other options are available to you, you'll have to use x264.
There are 4 options for rate Control
- VBR
- CBR
- CQP
- Lossless
VBR - Variable Bitrate: Chooses a variable bitrate based on two parameters, an average birate and a max birate. Decent quality, but can have inconsistent filesize.
CBR - Constant Bitrate: Uses a user-set bitrate to encode with. Good quality, allows for controlling filesize at the cost of quality.
CQP - Constant Quantization Parameter: it chooses a variable bitrate based on the QP and content being recorded, but is much better (faster, higher quality) than VBR.
Lossless: No rate control, meaning very little compression. Massive file size, no quality loss from source.
Why shouldn't I set my second GPU in OBS?
Unless you have a SLI (NV Link) or XFIRE, this would have to transfer the B-Frames for encoding from one GPU across the PCI lanes to the CPU and back to the other GPU. Any processing power here would be lost to the transfer time.