[pulseaudio-discuss] audio video out of sync

Thomas Martitz kugel at rockbox.org
Tue Feb 18 03:08:27 PST 2014

Am 18.02.2014 10:06, schrieb Tanu Kaskinen:
> On Tue, 2014-02-18 at 11:04 +0200, Tanu Kaskinen wrote:
>> On Tue, 2014-02-18 at 04:51 +0100, Malte Gell wrote:
>>> Am 16.02.2014 12:24, schrieb Tanu Kaskinen:
>>>> On the topic of audio/video sync, synchronization requires accurate
>>>> latency information. PulseAudio doesn't have that information. If the
>>>> audio lags by a constant amount all the time, then you can work around
>>>> the problem by configuring the latency offset with e.g. pavucontrol.
>>> Thanks for the explanation.
>>> The audio lags do not occur all the time, they occur after some time,
>>> often audio totally quits, when waiting a while audio comes back again.
>>> /var/log/messages gets flooded with these errors:
>>> [bluetooth] module-bluetooth-device.c: Skipping 412706 us (= 72800
>>> bytes) in audio stream
>>> [bluetooth] module-bluetooth-device.c: Skipping 465700 us (= 82148
>>> bytes) in audio stream
>>> [bluetooth] module-bluetooth-device.c: Skipping 154683 us (= 27284
>>> bytes) in audio stream
>>> [bluetooth] module-bluetooth-device.c: Skipping 126688 us (= 22344
>>> bytes) in audio stream
>>> [bluetooth] module-bluetooth-device.c: Skipping 70714 us (= 12472 bytes)
>>> in audio stream
>>> Do these message give a hint where the problems come from?
>> The messages indicate that the kernel is accepting audio from PulseAudio
>> slower than what is required for smooth playback. I would guess that the
>> problem is interference in the radio signal that prevents reliable
>> communication.
> I forgot to mention - these messages do not give any hints about why the
> latency is increasing, that is, which buffer is getting bigger.

Doesn't this also appear for network streams, where each network-induced 
skip adds to the stream latency without any kind of recovery. I.e. PA 
never decreases the buffers again so that it can easily reach a couple 
of seconds?

Best regards

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