[pulseaudio-discuss] Pulseaudio latency

Fri Aug 10 05:58:58 UTC 2018

On Wed, Aug 1, 2018 at 12:27 AM Georg Chini <georg at chini.tk> wrote:

> On 31.07.2018 10:22, Harish Gaddameedi wrote:
>
>
> On Tue, Jul 31, 2018 at 12:42 PM Harish Gaddameedi <
> harish.gaddameedi at smartron.com> wrote:
>
>> On Tue, Jul 31, 2018 at 12:11 PM Harish Gaddameedi <
>> harish.gaddameedi at smartron.com> wrote:
>>
>>>
>>>
>>> *Please do not top-post. To me it looks like that is an issue in the
>>> ALSA driver and not related to pulseaudio. The driver must be reporting the
>>> wrong latency. Did you set the loopback latency to*
>>> *300 ms? Default is 200 ms.*
>>>
>>>
>>> Sorry, I use default settings, gmail is doing top posting.
>>> No, i didn't set any loopback latency. I'll check with the alsa driver
>>> and get back to you.
>>>
>>> --
>>> Thanks,
>>> Harish Gaddameedi
>>>
>>
> Hi Georg,
>
> There is one more important point i wanted to discuss, this is which we
> have capture from your reply of clock synchronisation. Can you conform
> whether the system clock and audio clock both are same or different?
>
>
> System clock and audio clock need not be equal. Each sound card has its own
> clock which might not be synchronized with system clock or wall clock.
> Basically, if your sound card claims to run on 44100 Hz, it may be slightly
> more or less if measured in "real" (wall clock) time.
> module-loopback is normally capable of detecting the clock difference and
> adjusts the sink-input sample rate so that the latency remains constant.
> This
> is why you see in the log, that the module is not using 44100 Hz but in
> fact
> some other (in your case lower) sample rate. PA then does re-sampling
> from that rate to your sound card rate.
>
> For the A2DP sink (bluetooth headset or speaker) the system clock is used
> for timing, so for this special case the audio clock matches system clock.
>

Hi Georg,

I have found some cause for the pulseaudio Latency, can you please look
into the below log. During this process of "*alsa-sink.c: Tried rewind, but
was apparently not possible*", the latency is coming.

Fri Aug 10 11:21:28 2018 user.info pulseaudio[4396]: (50087.559|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: Tried rewind, but was apparently
not possible.
Fri Aug 10 11:21:28 2018 user.debug pulseaudio[4396]: (50087.575|   0.015)
[alsa-sink-I2S cx2072x-dsp-0] protocol-native.c: Requesting rewind due to
end of underrun.
Fri Aug 10 11:21:28 2018 user.debug pulseaudio[4396]: (50087.575|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] protocol-native.c: Requesting rewind due to
end of underrun.
Fri Aug 10 11:21:28 2018 user.debug pulseaudio[4396]: (50087.577|   0.001)
[alsa-sink-I2S cx2072x-dsp-0] protocol-native.c: Requesting rewind due to
end of underrun.
Fri Aug 10 11:21:28 2018 user.debug pulseaudio[4396]: (50087.579|   0.002)
[alsa-sink-I2S cx2072x-dsp-0] protocol-native.c: Requesting rewind due to
end of underrun.
Fri Aug 10 11:21:28 2018 user.debug pulseaudio[4396]: (50087.580|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] sink-input.c: Requesting rewind due to
uncorking
Fri Aug 10 11:21:28 2018 user.debug pulseaudio[4396]: (50087.580|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: Requested to rewind 76608 bytes.
Fri Aug 10 11:21:28 2018 user.debug pulseaudio[4396]: (50087.580|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: Limited to 68288 bytes.
Fri Aug 10 11:21:28 2018 user.debug pulseaudio[4396]: (50087.581|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: before: 17072
Fri Aug 10 11:21:28 2018 user.debug pulseaudio[4396]: (50087.581|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: after: 0
Fri Aug 10 11:21:28 2018 user.info pulseaudio[4396]: (50087.581|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: Tried rewind, but was apparently
not possible.
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.231|   2.650)
[alsa-sink-I2S cx2072x-dsp-0] sink-input.c: Requesting rewind due to corking
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.231|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: Requested to rewind 76608 bytes.
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.232|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: Limited to 12992 bytes.
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.232|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: before: 3248
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.232|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: after: 0
Fri Aug 10 11:21:31 2018 user.info pulseaudio[4396]: (50090.232|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: Tried rewind, but was apparently
not possible.
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.241|   0.009)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: hwbuf_unused=0
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.241|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: setting avail_min=18193
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.242|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: Requested to rewind 76608 bytes.
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.242|   0.000)
[pulseaudio] core.c: Hmm, no streams around, trying to vacuum.
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.242|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: Limited to 12992 bytes.
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.242|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: before: 3248
Fri Aug 10 11:21:31 2018 user.debug pulseaudio[4396]: (50090.242|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: after: 0
Fri Aug 10 11:21:31 2018 user.info pulseaudio[4396]: (50090.242|   0.000)
[alsa-sink-I2S cx2072x-dsp-0] alsa-sink.c: Tried rewind, but was apparently
not possible.

*When the below log came, the music played successfully.*

Fri Aug 10 11:21:31 2018 user.info pulseaudio[4396]: (50090.243|   0.000)
[pulseaudio] sink-input.c: Freeing input 445 "Playback Stream"
Fri Aug 10 11:21:31 2018 user.info pulseaudio[4396]: (50090.247|   0.004)
[pulseaudio] client.c: Freed 246 "gstreamer_play"
Fri Aug 10 11:21:31 2018 user.info pulseaudio[4396]: (50090.247|   0.000)
[pulseaudio] protocol-native.c: Connection died.

-- 
Regards,
Harish Gaddameedi
Software Engineer
Mobile: +91- 9246040475
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20180810/104d82d3/attachment-0001.html>