[pulseaudio-discuss] A2DP - Bluetooth source to alsa sink audio routing

Cristina Cristea doina.cristina at gmail.com
Tue Feb 22 05:19:04 PST 2011

Hi guys,

First of all, sorry if this problem has been discussed before. I'm new 
on this list and haven't seen it on the archives.

Shortly, I'm experiencing small underruns when playing music from the 
phone to my computer through bluetooth. At about every 5-6 minutes, the 
music stops  for 1-2 sec. and these messages are showed by pulseaudio:

D: protocol-native.c: Underrun on 'lt-pacat', 0 bytes in queue.
D: protocol-native.c: Requesting rewind due to end of underrun.
D: alsa-sink.c: Requested to rewind 65536 bytes.
D: alsa-sink.c: Limited to 44400 bytes.
D: alsa-sink.c: before: 11100
D: alsa-sink.c: after: 11100
D: alsa-sink.c: Rewound 44400 bytes.src-sinc-best-quality
D: sink.c: Processing rewind...
D: sink-input.c: Have to rewind 44400 bytes on render memblockq.
D: source.c: Processing rewind...

I am using pacat and paplay apps as follows: parec -r --format s16le 
--channels 2 --rate 44100 | paplay -p

I also tried to redirect audio with module-loopback module: load-module 
module-loopback source=bluez_source.00_23_76_E3_F3_C5 
The results are still dissatisfactory:
-the CPU load is about 60%

-every 10 seconds, module-loopback is changing the sample rate which is 
not so pleasant for the listener:
I: module-loopback.c: Loopback overall latency is 56.37 ms + 493.72 ms + 
135.29 ms = 685.38 ms
I: module-loopback.c: Should buffer 23552 bytes, buffered at minimum 
24288 bytes
I: module-loopback.c: Old rate 44167 Hz, new rate 44118 Hz

-underruns are still showing and pulseaudio displays:
I: module-loopback.c: Coud not peek into queue

I'm running a meego and have this sound card:
0 [MID            ]: HDA-Intel - HDA Intel MID
                       HDA Intel MID at 0xd2c00000 irq 16

I'm not sure if this is a bluez or pulseaudio issue. I have tried my 
bluetooth and a bluetooth dongle and there is no difference.

My question is: is there a better way to route audio in this case? One 
that could synchronize better the bluetooth and the sound card?


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