[pulseaudio-discuss] bluetooth latencies

[Georg Chini]

On 30.01.2017 18:37, Alexander E. Patrakov wrote:
> I am not a bluetooth expert, but: is this a different latency? Maybe
> the situation is that the headset has its own 28-ms buffer, and
> PulseAudio adds 25 or 125 ms on top of that?

What do you mean by different latency? The values are passed
to pulse via pa_{sink, source}_set_fixed_latency_within_thread()
(plus one write block size). So pulse reports 128 ms fixed latency
for the SCO sink, while the current latency is around 28 ms.

>
> 2017-01-30 21:35 GMT+05:00 Georg Chini <georg at chini.tk>:
>> 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?
>>
>> Regards
>>               Georg
>>
>> _______________________________________________
>> pulseaudio-discuss mailing list
>> pulseaudio-discuss at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
>
>