CPU feature for (Twitch) streaming

[kafeaulait]

Hi guys, this thread is less about build recommendation and more of a general knowledge inquiry. If there is an existing repository of information about game streaming in general, I'd appreciate being pointed there as well!

 

The question is:

Quote

What feature(s) should one look for in a CPU for the specific use case of [Game Streaming], i.e. 1080p or 1440p @ 60fps gaming + live streaming.

 

A couple possibilities I've thought of with my existing knowledge on the subject:

 

• Using GPU encoding: With the GTX 1000-series and RX 400-series GPUs offering excellent performance at affordable prices, hardware-accelerated encoders seem to be commonplace for a minimal performance hit. This means the CPU choice isn't likely to make much of a difference. True/False? Why?
• Using CPU encoding: I've heard in passing that CPU encoding can make the stream look better (even though anecdotally I have not had much success with my Ivybridge i5 from 2012). 
  • Is this worth it in some cases? How? What are the considerations?
  • What would be some specs to consider in the CPU for this use case? Thread count? Core count? Single core clock speed? Cache? Some obscure video encoding technology nobody has made a big deal about?

Feel free to elaborate on more extreme use cases (e.g. 4k/8k at 144fps gaming) as well if they are relevant.

[Sakkura]

GPU encoding is a thing, but it is less flexible than CPU (software) encoding. The latter can be set to whatever bitrate, codec, and quality you like. GPU encoding is fixed-function hardware.

 

If you do use GPU encoding, the CPU itself doesn't matter much.

 

If you use CPU encoding, multithreaded performance matters. And that's essentially the product of IPC, clock frequency, and core count (multiplied by another 1.3 or so for hyperthreading). More cores and hyperthreading helps, but so does faster individual cores.

[Tosa]

Processors with integrated graphics can also do hardware encoding without any performance loss. And you can choose the bitrate with hardware encoding, and hardware encoding supports a few codecses. 

 

Anyway, if you want to stream to twitch, forget 1440p and even 1080p at 60 fps: you're not allowed to go beyond 3500kbps, which is enough for 720p 30fps, and you'll still get noticeably lowered quality in some cases. 

[kafeaulait]

10 minutes ago, Tosa said:

Anyway, if you want to stream to twitch, forget 1440p and even 1080p at 60 fps: you're not allowed to go beyond 3500kbps, which is enough for 720p 30fps, and you'll still get noticeably lowered quality. 

I'd prefer to avoid solutions that hinge on existing technologies, as the facts change constantly. Not only is it not true that Twitch enforces a hard cap of 3500 kbps (in fact, it is their advised maximum for technical reasons), but it also does not translate well to other existing services, future technology, or similar use cases (local recording).

Edited February 1, 2017 by kafeaulait
Wrong link