On Fri, 2019-10-11 at 19:00 +0000, Gix, Brian wrote: > Hi Pali, > > On Fri, 2019-10-11 at 20:35 +0200, Pali Rohár wrote: > > Currently bluez API, method Acquire() already inform called application > > what is socket MTU for input and output. So from this information it is > > possible to detect if device supports EDR 3 or not. > > > > But it is too late to have this information. I need to send SBC > > parameters to bluez first when doing A2DP negotiation, this is early > > steps before Acquire() is called. > > This seems to be the kind of information which is fixed, for the life of the pairing. > > What if you assumed the lower speed the first time you connected, determined the > speed during the first streaming, and then either immediately renegotiate (caching the identifying > information > of the SNK), or just cache the information for future connections. > > Or the reverse, and assume fast, but immediately adjust down if you aren't getting what you hoped for. > > In any case, this would be a "Device Setup" glitch which you could note as a routine part of pairing in the > documentation. Or, Stream "Silence" the first time you connect, in order to determine throughput. It would add 1-2 seconds to your connection time perhaps, but would be less noticable to the user. > > > Therefore I'm asking for some way how to get information if device > > supports EDR 2 or EDR 3. This is basically requirement for proper > > implementation of SBC in high quality mode. So if there are not such API > > yet, could it be exported from kernel to userspace and bluetoothd > > daemon? > > > > See these two articles for more details about SBC and its high quality: > > > > https://habr.com/en/post/456182/ > > http://soundexpert.org/articles/-/blogs/audio-quality-of-sbc-xq-bluetooth-audio-codec > > > > > > Is there any bluez API for it? > > > >
