[pulseaudio-discuss] bluetooth latency gets gradually worse over time

[Arun Raghavan]

On 1 May 2016 at 08:07,  <mudrunka at spoje.net> wrote:
> Hello,
> i have issue with bluetooth speaker. it creates loud pop when it's
> (un)suspended by module-suspend-on-idle. so i proceeded to disable
> suspend-on-idle, but when i leave it on for few hours, the latency gets
> huge. Like 2 seconds or more. I suppose it has something to do with DAC
> clock (or samplerate) in bluetooth speakers being little bit slower than
> nominal. And the error adds up over time resulting in growing latency.
>
> When i manualy reconnect to speaker it gets fixed.
>
> Do you have any idea how to fix this? I think it needs something that will
> reset the stream when no audio is played, pretty much like suspend-on-idle
> does, but without powering the bt device off (which causes pop). it's really
> annoying. sometimes it scares the crap out of me, when speakers are on full
> volume and it pops when i eg. receive IM mesage. :-) also it's probably not
> healthy for the speakers (i use conventional speakers with amp and bt
> receiver).
>
> I know the popping is mostly HW error. But it can be worked around by
> disabling suspend-on-idle, which then causes latency problems (also somehow
> HW related). And i think the latency problem can be somehow fixed in SW by
> restarting the stream or cleaning some buffer that causes the latency...
>
> BTW 2 seconds of latency are quite a lot... Is there even chance, that cheap
> BT device has 2 second buffer? Maybe it's pulse audio that has 2 second
> latency. And it would be easily fixed by not buffering silence. Or by
> deleting this buffer when idle.

That does sound like a large latency. Could you file a bug about that,
and hopefully I'll get some time to test this out to see if it happens
locally too? If we do fix that, it looks like your problem should just
be fixed.

Cheers,
Arun