-maxrate and -bufsize settings for streaming off USB with hardware decoder?

[Shaocaholica]

I'm running some tests for streaming 4k@24fps H.264 video off of a USB2 drive and being decoded by a hardware decoder that can handle (on paper) 120,000kbit max. To give myself some headroom I'm setting -maxrate to 95,000k (which is already pretty damn high) but I'm not sure what I should use for -bufsize given that I'll be streaming from USB. Is there some good method to derive -bufsize given my maxrate and interface practical rate (USB2, ~280,000k real world max).

Right now I'm just playing with:

-maxrate 95000k -bufsize 150000k

[Asmodian]

I would think -bufsize should be set based on your desired startup time and/or memory available in the hardware decoder? As I understand VBV it is only -maxrate that would be influenced by the USB2 speed.

[Blue_MiSfit]

The general best practice is to use at least a second of buffer - ideally more. Some situations require much less - like low latency scenarios and picky hardware, but you can usually get away with a second or two.

More than 2-3 seconds is diminishing returns in most cases IMO.