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From: "Gix, Brian" <brian.gix@intel.com>
To: "pali.rohar@gmail.com" <pali.rohar@gmail.com>
Cc: "iam@valdikss.org.ru" <iam@valdikss.org.ru>,
	"linux-bluetooth@vger.kernel.org"
	<linux-bluetooth@vger.kernel.org>
Subject: Re: Determinate EDR speed
Date: Fri, 11 Oct 2019 19:05:56 +0000
Message-ID: <64060b6a2bc9aee7b7eef0347ee3bafe3fddd18b.camel@intel.com> (raw)
In-Reply-To: <fea0a8efd80c4c444f56d4f3902aeae4f4f9de32.camel@intel.com>

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?
> > > > 

  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-11  8:27 Pali Rohár
2019-10-11 18:15 ` Gix, Brian
2019-10-11 18:35   ` Pali Rohár
2019-10-11 19:00     ` Gix, Brian
2019-10-11 19:05       ` Gix, Brian [this message]
2019-10-11 20:04         ` Pali Rohár
2019-10-12  7:23           ` Luiz Augusto von Dentz
2019-10-13  7:36             ` Pali Rohár
2019-10-13  8:45               ` Luiz Augusto von Dentz
2019-10-13  9:39                 ` Pali Rohár
2019-10-13  9:49                   ` Luiz Augusto von Dentz
2019-10-16 19:06                   ` Marcel Holtmann
2019-10-16 19:13                     ` Pali Rohár
2019-10-19 19:47                       ` Marcel Holtmann
2019-10-16 19:05           ` Marcel Holtmann

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