[pulseaudio-discuss] Pulseaudio latency

Harish Gaddameedi harish.gaddameedi at smartron.com
Sun Jul 29 10:44:52 UTC 2018

 Hi Georg,

I was working on simple Openwrt Platform, and Source device is Android
phone Bluetooth with Youtube app 24 hrs live streaming video and alsa
device is speaker, which is hardwired

The 12 hrs testing which i did on pulseaudio-11.1 are without my
modification. The basic modification which i made in the previous
pulseaudio-8.0 is with the idle state of bluez_source card (i.e., card is
vanishing when the song is in the pause state) and did some changes to
buffers of pulseaudio to reduce the latency. But in pulseaudio-11.1 i
didn't do all the changes as i didn't find any initial latency. but
periodic latency after 12hrs still exists. The issue is reproducible with
Gstreamer also.

I haven't worked on microphone scenarios, I'm just working on music player
and speaker.

Let me clear you some test scenarios for better understanding,
Case 1: Android phone as source (bluez_source) and device with internal
speaker (alsa-sink as sink for pulseaudio) -------> delay after 12hrs
Case 2: Device with Gstreamer as source and same device with internal
speaker (pulsesink with alsa card as sink for pulseaudio) ----------> delay
after 12 hrs exists.
Case 3: Device with Gstreamer as source and External Bluetooth speaker
(pulsesink with bluez_sink card) -----------> No delay after 12 hrs.

On Sun, Jul 29, 2018 at 3:09 PM Georg Chini <georg at chini.tk> wrote:

> On 28.07.2018 11:20, Harish Gaddameedi wrote:
> Dear Georg,
> Thanks for reply,
> As you have suggested. I have updated the pulseaudio to the later version
> which is after pulseaudio-10.0 (i.e., pulseaudio-11.1). We have found that
> the delay is still exists after playing any music upto 12hrs. We found like
> the audio and video are completely out of sync with a delay of 4-5 seconds.
> In the change log between pulseaudio-11.1 and pulseaudio-12.2,  i haven't
> seen any updates regarding latency. I hope that the latency will also be
> exist in pulseaudio-12.2 also.
> Thanks,
> Harish Gaddameedi.
> On Fri 27 Jul, 2018, 11:20 AM Georg Chini, <georg at chini.tk> wrote:
>> On 27.07.2018 07:10, Harish Gaddameedi wrote:
>> I'm working on an Application using pulseaudio package using
>> pulseaudio-8.0, made lot of modifications in the pulseaudio to reduce the
>> fluctuation of source card and to reduce the initial latency, I'm
>> successful in doing this process. On 12 hrs testing of audio with alsa-sink
>> module, I'm finding the latency of 4-5 seconds. When testing the same 12hrs
>> in connection with External bluetooth speaker, there is no latency found.
>> After the 12 hrs testing with alsa-sink, latency from Module-loopback is
>> showing as less than 300ms which is fine. but the latency reproducible is
>> upto 4-5seconds. Can anyone give me a quick pointer if you have faced
>> the similar issue?
>> Thanks,
>> Harish Gaddameedi
>> Hi,
>> I would suggest to update to a newer version of PA. Current version is
>> 12.2.
>> Module-loopback did not control the latency very well prior to 10.0. If
>> you
>> have the same issue with a current PA version, this would need more
>> investigation.
>> Regards
>>             Georg
> Hello Harish,
> what kind of alsa device are you using on what platform? What did you
> modify
> within PA? Did you try 11.1 without your modifications? What exactly is
> your setup?
> If you are talking about A/V synchronization, the player may also be the
> cause of
> the issue. Sound card time does not necessarily match system time, so the
> player
> has to take care of the difference. The bluetooth A2DP sink uses the
> system clock
> for timing, that's probably why you don't have the problem there. Does
> something
> similar happen when you loop back your microphone to the ALSA sink?
> I have run module-loopback for days on an Intel platform with standard
> hda-intel
> and USB devices without seeing any delays. Also, in 11.1 there should be
> no need
> to reduce initial latency because module-loopback will adjust quickly to
> the latency
> you requested.
> Regards
>              Georg

Harish Gaddameedi
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