Recording/Streaming – Choose your bitrate

Local Recording

For a local recording we have two options. First of all we can just “un-limit” the bitrate. That way the encoder will just use as much bitrate as he wants to. Since we are not streaming right away, we do not have to worry about our upload speed or similar stuff. But before we would upload the files later to youtube we would probably want to re-encode them to a slightly smaller bitrate. So our second option would be selecting a maximum bitrate to limit the encoder options a bit. Be aware this can possibly in the worst case degrade your quality significantly.

Let us first take a look at the settings to “un-limit” the bitrate:

Encoding Advanced Options
Use CBR: Disabled
Bitrate: 1000
Use custom buffer size: Enabled
Buffer size: 0
Use custom x264 parameters: Enabled
Custom x264 parameters: crf=X

Where X is anywhere from 0-25, lower being higher quality and slightly higher CPU usage. A good place to start is in the range of 15 – 20. Setting CRF to 0 enables lossless recording which will result in a very high file size and also high CPU requirements while possibly introducing compatibility issues! For compatibility with various editing software, it is also recommended to enable CFR (advanced options) and again do not use CRF 0 as it uses “High 444” mode which a lot of editing software (and some video players) cannot handle.

If your upload speed is very limited or you do not plan on editing the files before upload anyway, you can also just set a slightly more fixed variable bitrate. Now in this case you have to make sure to use enough bitrate for every scenario that could happen. (For example very long high movement action on the screen, that normally uses a ton of bitrate to look very good)
In my bitrate tests for the Online Streaming part of this guide (see below) I noticed that even the most demanding game looks good, on a bitrate of around 16mbit or more. Quality calculations speak of a 95% similarity to the original. So you only loose a very small amount of details in the whole picture. The settings would look like this:

Encoding
Use CBR: Disabled
Quality Balance: 10
Bitrate: 20000(or more)
Use custom buffer size: Disabled

Online Streaming

If you plan to do livestreaming, the first thing you will have to do is a speedtest. You have to know your possible upload speeds as it sets a starting point for us. Of course we will also have to take into consideration that our computer might not be powerful enough to livestream at our desired settings. But with your upload speed we can take a look at the possible options. 

Bitrate_Streamen

Of course these are just rough guidelines to start with. For most current services (Twitch, Youtube, etc.) you will want to activate CBR (Constant Bitrate) in your Streaming Software. And then start testing. Lower bitrates are better for a bigger amount of possible viewers. Higher bitrates are better for a good quality but will require better hardware and internet connections of your users. Keep an eye on your system´s CPU usage. If you have enough free processing power available you can look into tweaking your cpu-preset. But do this step by step (veryfast -> fast, then fast -> faster, etc.) and check that your Software still runs smooth and has some free room.

A “slower” preset adds more compression to the video, which will produce a better looking image but at an increased CPU usage. And thats about it, you will have to test a bit, and might encounter problems, or even bugs in a software. Dont let those things stop you and as always, be sure to add a comment if you have a question or annotation.

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