Introduction to low bitrate streaming
As you’ve most likely noticed by now, streaming with a low upload speed makes the stream look really bad and buffer a lot.
That's because encoding and bitrate and closely connected. It's either high bitrate and low encoding power or vice versa.
The benefits of using CPU Encoding
Encoding your streams using your CPU will make them look much better, as CPUs make fewer mistakes than GPUs, but take more power doing so. This means that the encoded video has fewer artefacts and blurring when there’s a lot of movement.
But you really should only encode your streams with your CPU when you have:
sub 1Mbit/s upload speed
a dedicated computer for streaming
a powerful CPU that won't harm game performance too much.
Because the stream's quality means nothing, when the game barely runs. More on this later.
What should my bitrate be?
My upload speed is around 720 kbit/s so to be on the safe side I’ll stream at 670 kbit/s in case there’s some fluctuation in upload speed (there will be) and rescale the stream to 480p so the bits don't have to be so scattered around allowing for better detail. A constantly buffering stream is a no bueno¹
Audio Bitrate:
Under Settings, Output, Audio set the bitrate to something between 96 and 160. Going under 96 is not at all recommended unless you cosplay as a robot and going above 160 is just wasted bits that could’ve been used for video. On Twitch.TV the bitrate above 160 won’t even be transmitted to anyone.
Just so there's no confusion, audio bitrate is in the bitrate you set in the previous section, just reserved for audio.
CPU Encoding Settings
The faster paced the game you play the better you need to encode it to keep it looking OK. But when there isn’t that much changing constantly on the screen you don’t have to stress your CPU that much and encode at a lower quality. You might not even be able to play any fancier fast-paced games at all because the encoding takes up all the CPU power. Play around with the settings to find the sweet spot between the quality and the lag.
I’m using a 4-Core i7 3770. Using the ’slower’ present in PUBG drops my framerate to around 40fps from 100+. This is why you need a powerful, preferably more than 4 core CPU to keep your stream from looking crap.
Why 4+ cores? Games today rarely use more than 4 cores at a time, the cores used by the game will have to do less work as the cores unused will do most of the encoding. This is why AMD’s Ryzen processors are so good for streaming.²
Links for more on this subject
¹ Tom Scott on image compression https://xq.ms/tomscottcompression
² Linus Tech Tips on Ryzen CPUs for streaming https://xq.ms/lttryzen
Conclusion
To have your stream look good and not buffer you need to stream at a bitrate that's a lower than your upload speed and do as much CPU encoding as you can to make those few-hundred kilobits look as good as they are.
The stream's resolution should be around 480p, so the bits don't have to be too scattered around, again, making the image look blurry.
But the encoding isn't everything, when there are only a few hundred thousand 1s and 0s you can't expect to have the output look as crisp as a few million 1s and 0s.
Thanks for reading and happy streaming!