[pulseaudio-discuss] bluetooth latencies

[Tanu Kaskinen]

On Mon, 2017-01-30 at 17:35 +0100, Georg Chini wrote:
> Hello,
> 
> in module-bluez5-device.c and module-bluez4-device.c, latencies for
> bluetooth are defined as follows:
> 
> #define FIXED_LATENCY_PLAYBACK_A2DP (25 * PA_USEC_PER_MSEC)
> #define FIXED_LATENCY_PLAYBACK_SCO (125 * PA_USEC_PER_MSEC)
> #define FIXED_LATENCY_RECORD_A2DP   (25 * PA_USEC_PER_MSEC)
> #define FIXED_LATENCY_RECORD_SCO    (25 * PA_USEC_PER_MSEC)
> 
> Is the fixed latency for SCO playback a mistake? Both headsets I own
> report around 28 ms actual latency for the SCO sink, so I cannot
> understand why the fixed latency is set to 125 ms. Should I send a
> patch to correct it?

I don't know how Lennart came up with these numbers. How did you get
the latency report from the headset? AFAIK, the reason why these
constants exist is that we don't have a way to query the latency with
bluetooth, and reporting some latency is likely more accurate than
reporting zero latency.

-- 
Tanu

https://www.patreon.com/tanuk