[pulseaudio-discuss] Timing interval for Bluetooth Wideband speech

[Sathish Narasimman]

Hi Tanu,


On Sat, Mar 17, 2018 at 1:26 AM, Tanu Kaskinen <tanuk at iki.fi> wrote:

> On Thu, 2018-03-15 at 14:49 +0530, Sathish Narasimman wrote:
> > Hi,
> >
> > I would like to know the PulseAudio module that is responsible for
> pushing
> > the audio for every 1 millisecond.
> >
> > For NBS the packets are pushed with 48bytes and 1milli sec interval.
>
> Where does this 1 ms interval come from? The audio that pulseaudio
> writes with SCO is mono, 16-bit, 8000 Hz. With that specification 48
> bytes means 3 ms packets, not 1 ms.
>
> > But for WBS the timing between 2 SCO packets needs to be *7.5 Milli Sec.*
> >
> > *May I know how to change the packet interval between the 2 SCO packets.*
>
> The write_block_size variable in src/modules/bluetooth/module-bluez5-
> device.c controls how big packets pulseaudio writes. That in turn is
> calculated based on write_link_mtu, and that comes from the transport
> acquire() callback. The ofono backend always returns 48 bytes. The
> native backend returns 48 bytes by default, but it can also be
> configured to ask the kernel what the real MTU is.
>
>
I am able to set the MTU to 60 bytes in the and able to make the SCO
connection.
But still, the data rate is maintained as 1 msec.

Do we need to introduce any latency in the PA?
As per core spec 5 , Vol 4 Part B of USB transaction the HCI
packet interval need to be 7.5msec.
Do we need to maintain the rate in PA?



> --
> Tanu
>
> https://liberapay.com/tanuk
> https://www.patreon.com/tanuk
> _______________________________________________
> pulseaudio-discuss mailing list
> pulseaudio-discuss at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20180327/93706609/attachment.html>