Re: Determinate EDR speed

["Gix, Brian" <brian.gix@intel.com>]

Hi Pali,

On Fri, 2019-10-11 at 10:27 +0200, Pali Rohár wrote:
> Hello!
> 
> I would like to ask, how can userspace application which uses bluez DBus
> API determinate EDR speed of remote bluetooth device?
> 
> Particularly, I'm interested in detection if bluetooth headset supports
> EDR 2 Mbps or EDR 3 Mbps speed and based on this decide which SBC
> parameters would be used for encoding audio via SBC codec.

There are a variety of things that can affect real-time throughput, and I think even EDR 2 vs 3 might
dynamically change to fit the current conditions.  If you have the ability to have fine control of the SBC
parameters, I think the *best* way to adjust for throughput is to choose what sample rate and subands you
want, and then squeeze or expand the bitpool to fit your throughput. (bitpool is something that can be
dynamically adjusted, I believe, without re-negotiation).

Howeverever, the real question is how to tell what the instantaneous realtime throughput is...  which is
certainly affected by support for EDR2 vs EDR3, but is also affected by distance, RSSI, environmental RF, and
what the other L2CAP channels on the connection are carrying (AVRCP for example).

I don't think a simple boolean for EDR2 and/or EDR3, especially in user space, is going to give you the level
of information you need.

> 
> Is there any bluez API for it?
>