Dear Georg,
thanks for the answers, I really like your 2nd solution.
But the problem is, add a another module-loopback in front speaker
path, which means I need a another
pair of alsa drivers (as alsa-sink.0 and alsa-source.0 in the pic),
that what I have written to the
alsa device, then I can read the data back from the input alsa
device. It`s not a valid solution with our
current hardware.
also another problem is that: we support dynamic switch the sink of
the pa_stream (pa_sink_input_move_to)
we have 3 way to playback current stream:
1. front speaker path only
pa_stream -> alsa-sink.1 -> front-speaker
2. rear speaker path only
pa_stream -> alsa-sink.0 -> alsa-source.0 -> alsa-sink.2 (within a
module-loopback )
3. front and rear speaker combine
pa_stream -> combine-sink -> alsa-sink.1 -> front-speaker
-> alsa-sink.0 -> alsa-source.0 ->
alsa-sink.2 (within a module-loopback )
I`m not sure may be I can add a fake a module-loopback, just memory
copy but wait for a while to simluate the lantency ?
Thanks anyway!
BR,
Lixin
在 2015年05月06日 14:05, Georg Chini 写道:
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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