[pulseaudio-discuss] need help with audio sync

[Georg Chini]

On 06.05.2015 04:17, golden wrote:
>
> Dear PulseAudio folks,
>
>       
>       We are using PulseAudio in our automotive project, the progress is pretty good so far.
>       I need some help for solving the sync problems between two speakers.
>      The pic below is the data flow of the two speakers:
>
>
>
>
>     without any syncing method, what we hear from the front-speaker is 
> ahead of the rear-speaker (real-spear is slower for sure), our goal is 
> that make the rear-speaker almost sync with (or catch up) the front 
> speaker.
>
Hi,

with your manipulation of the audio and with module-loopback you 
introduce quite a lot of latency into the
first path. Maybe you can simply set the latency of alsa-sink.1 larger 
than that of alsa-sink.0, not sure if this works.
Otherwise I would suggest to make the paths look more or less 
equivalent, that would mean putting a
module-loopback into the front speaker path.

You could also try and use my (not yet reviewed) patches for 
module-loopback at
http://thread.gmane.org/gmane.comp.audio.pulseaudio.general/22956
which allow a better control over the latency introduced by the module.
If you use the patches and have a module-loopback in both paths you 
should be able to fully synchronize
them by adjusting the latencies of the two modules.

Regards
             Georg
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