[pulseaudio-discuss] need help with audio sync

[golden]

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:




  below is the pactl list modules information :

    uid=0 gid=0 at nutshell:/ # pactl list sinks
Using shared memory pool with 1024 slots of size 64.0 KiB each, total 
size is 64.0 MiB, maximum usable slot size is 65496
Trying to connect to /tmp/pulse/native...
SHM possible: yes
Protocol version: remote 30, local 30
Negotiated SHM: yes
Sink #0
     State: RUNNING
     Name: audioio.5
     Description: (null)
     Driver: module-audioio-sink.c
     Sample Specification: s16le 2ch 48000Hz
     Channel Map: front-left,front-right
     Owner Module: 3
     Mute: no
     Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 
100% / 0.00 dB
             balance 0.00
     Base Volume: 65536 / 100% / 0.00 dB
     Monitor Source: audioio.5.monitor
     Latency: 0 usec, configured 128000 usec
     Flags: HARDWARE DECIBEL_VOLUME LATENCY
     Properties:
         device.icon_name = "audio-card"
     Formats:
         pcm

Sink #4
     State: RUNNING
     Name: audioio.0
     Description: (null)
     Driver: module-audioio-sink.c
     Sample Specification: s16le 2ch 48000Hz
     Channel Map: front-left,front-right
     Owner Module: 8
     Mute: no
     Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 
100% / 0.00 dB
             balance 0.00
     Base Volume: 65536 / 100% / 0.00 dB
     Monitor Source: audioio.0.monitor
     Latency: 0 usec, configured 128000 usec
     Flags: HARDWARE DECIBEL_VOLUME LATENCY
     Properties:
         device.icon_name = "audio-card"
     Formats:
         pcm

Sink #5
     State: RUNNING
     Name: audioio.1
     Description: (null)
     Driver: module-audioio-sink.c
     Sample Specification: s16le 2ch 48000Hz
     Channel Map: front-left,front-right
     Owner Module: 9
     Mute: no
     Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 
100% / 0.00 dB
             balance 0.00
     Base Volume: 65536 / 100% / 0.00 dB
     Monitor Source: audioio.1.monitor
     Latency: 228454 usec, configured 250000 usec
     Flags: HARDWARE DECIBEL_VOLUME LATENCY
     Properties:
         device.icon_name = "audio-card"
     Formats:
         pcm

Sink #6
     State: RUNNING
     Name: audioio.6
     Description:  audioio.0, audioio.1
     Driver: module-iauto-combine-sink.c
     Sample Specification: s16le 2ch 48000Hz
     Channel Map: front-left,front-right
     Owner Module: 7
     Mute: no
     Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 
100% / 0.00 dB
             balance 0.00
     Base Volume: 65536 / 100% / 0.00 dB
     Monitor Source: audioio.6.monitor
     Latency: 130235 usec, configured 250000 usec
     Flags: DECIBEL_VOLUME LATENCY
     Properties:
         device.class = "filter"
         combine.slaves = "audioio.0,audioio.1"
         device.description = " audioio.0, audioio.1"
         device.icon_name = "audio-card"
     Formats:
         pcm


     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.

  so my question is how, is there any good way to solve it in our 
existing framework ?

  Thanks! (sorry for my bad explanation since English is not my native 
language)



BR,
Lixin
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