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Audio channels randomly reversed #4314

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frdskn opened this issue Feb 18, 2025 · 1 comment
Open

Audio channels randomly reversed #4314

frdskn opened this issue Feb 18, 2025 · 1 comment

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@frdskn
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frdskn commented Feb 18, 2025

Describe the bug

Upon PJSUA initialization and audio output selection, the channels of a stereo output can randomly be reversed.

Steps to reproduce

I am using a stereo output as two independent mono channels.

With the ALSA configuration:

pcm.chanA {
        type plug
        slave.pcm {
                type dshare
                ipc_key 123456
                slave.pcm "hw:0,0"
                slave.channels 2
                bindings.0 0
        }
}

pcm.chanB {
        type plug
        slave.pcm {
                type dshare
                ipc_key 123456
                slave.pcm "hw:0,0"
                slave.channels 2
               bindings.0 1
        }

... Run for instance speaker-test -D chanA -t sine -f 440 in the background then perform a default pjsua_create(), pjsua_init() (except for pjsua_media_config.channel_count=2, which is mandatory in this context), pjsua_start() sequence, followed by a pjsua_set_snd_dev() to direct the audio output to "chanB".

PJSIP version

2.15

Context

PJSUA lib used for VoIP only, on a custom board built around an ARM-based system-on-chip (Atmel/microchip SAMA5) and a Wolfson/Cirrus Logic WM8904 audio codec, which is supported by a platform-specific driver. Operating system is based on Linux 6.6 kernel and Debian 12

The test program (logs below) initialize pjsua as described above, invokes pjsua_set_snd_dev(), waits for 1 second, then performs pjsua_destroy(). Reversal chance is roughly 1 out of 5, and can happen when channels were already reversed (thus getting back to normal). If I remove pjsua_set_snd_dev() the problem doesn't happen.

The program which uses the second audio channel doesn't matter. It can be speaker-test or mpg123. Also AFAICT running speaker-test and mpg123 each on their channel doesn't cause a similar issue.

Log, call stack, etc

14:39:34.205 os_core_unix.c !pjlib 2.15 for POSIX initialized
14:39:34.209          pjlib  .select() I/O Queue created (0x256d98)
14:39:34.210 sip_endpoint.c  .Module "mod-msg-print" registered
14:39:34.211   pjsua_core.c  .PJSUA state changed: NULL --> CREATED
14:39:34.212 sip_endpoint.c  .Module "mod-pjsua-log" registered
14:39:34.212 sip_endpoint.c  .Module "mod-tsx-layer" registered
14:39:34.212 sip_endpoint.c  .Module "mod-stateful-util" registered
14:39:34.213 sip_endpoint.c  .Module "mod-ua" registered
14:39:34.213 sip_endpoint.c  .Module "mod-100rel" registered
14:39:34.213 sip_endpoint.c  .Module "mod-pjsua" registered
14:39:34.213 sip_endpoint.c  .Module "mod-invite" registered
14:39:34.311     alsa_dev.c  ..ALSA driver found 8 devices
14:39:34.312     alsa_dev.c  ..ALSA initialized
14:39:34.313          pjlib  ..select() I/O Queue created (0x28001c)
14:39:34.329 sip_endpoint.c  .Module "mod-evsub" registered
14:39:34.329 sip_endpoint.c  .Module "mod-presence" registered
14:39:34.330 sip_endpoint.c  .Module "mod-dlg_even" registered
14:39:34.330 sip_endpoint.c  .Module "mod-mwi" registered
14:39:34.330 sip_endpoint.c  .Module "mod-refer" registered
14:39:34.331 sip_endpoint.c  .Module "mod-pjsua-pres" registered
14:39:34.332 sip_endpoint.c  .Module "mod-pjsua-im" registered
14:39:34.332 sip_endpoint.c  .Module "mod-pjsua-options" registered
14:39:34.333   pjsua_core.c  .1 SIP worker threads created
14:39:34.334   pjsua_core.c  .pjsua version 2.15 for Linux-6.6.23/armv7l/glibc-2.21 initialized
14:39:34.335   pjsua_core.c  .PJSUA state changed: CREATED --> INIT
14:39:34.339   pjsua_core.c  SIP UDP socket reachable at 172.16.133.11:5060
14:39:34.340    udp0x259370  SIP UDP transport started, published address is 172.16.133.11:5060
14:39:34.341   pjsua_core.c  PJSUA state changed: INIT --> STARTING
14:39:34.342 sip_endpoint.c  .Module "mod-unsolicited-mwi" registered
14:39:34.343   pjsua_core.c  .PJSUA state changed: STARTING --> RUNNING
14:39:34.344    pjsua_aud.c  Set sound device: capture=-1, playback=0, mode=0, use_default_settings=0
14:39:34.345    pjsua_aud.c  .Opening sound device (speaker + mic) PCM@16000/2/20ms
14:39:34.362     ec0x25a548  ..Echo suppressor created, clock_rate=16000, channel=2, samples per frame=640, tail length=200 ms, latency=91 ms
14:39:34.363   sound_port.c  ..Sound port uses native clock
14:39:35.370   pjsua_core.c !Shutting down, flags=0...
14:39:35.370   pjsua_core.c  PJSUA state changed: RUNNING --> CLOSING
14:39:35.384   pjsua_call.c !.Hangup all calls..
14:39:35.384   pjsua_pres.c  .Shutting down presence..
14:39:36.394   pjsua_core.c !.Destroying...
14:39:36.394 sip_transport.  .Transport udp0x259370 shutting down, force=0
14:39:36.394  pjsua_media.c  .Shutting down media..
14:39:36.396     ec0x25a548 !Underflow, buf_cnt=0, will generate 1 frame
14:39:36.402     ec0x25a548  Underflow, buf_cnt=0, will generate 1 frame
14:39:36.407    pjsua_aud.c !...Closing chanB sound playback device and hw:CARD=socketA5,DEV=0 sound capture device
14:39:36.450   conference.c  ...Stop any transmission to port 0 (hw:CARD=socketA5,DEV=0)
14:39:36.450   conference.c  ...Stop any transmission from port 0 (hw:CARD=socketA5,DEV=0)
14:39:36.451   conference.c  ...Removed port 0 (hw:CARD=socketA5,DEV=0), port count=0
14:39:36.452 sip_transactio  .Stopping transaction layer module
14:39:36.452 sip_transactio  .Stopped transaction layer module
14:39:36.453 sip_endpoint.c  .Module "mod-unsolicited-mwi" unregistered
14:39:36.453 sip_endpoint.c  .Module "mod-pjsua-options" unregistered
14:39:36.453 sip_endpoint.c  .Module "mod-pjsua-im" unregistered
14:39:36.454 sip_endpoint.c  .Module "mod-pjsua-pres" unregistered
14:39:36.454 sip_endpoint.c  .Module "mod-pjsua" unregistered
14:39:36.454 sip_endpoint.c  .Module "mod-stateful-util" unregistered
14:39:36.454 sip_endpoint.c  .Module "mod-refer" unregistered
14:39:36.455 sip_endpoint.c  .Module "mod-mwi" unregistered
14:39:36.455 sip_endpoint.c  .Module "mod-dlg_even" unregistered
14:39:36.456 sip_endpoint.c  .Module "mod-presence" unregistered
14:39:36.456 sip_endpoint.c  .Module "mod-evsub" unregistered
14:39:36.456 sip_endpoint.c  .Module "mod-invite" unregistered
14:39:36.457 sip_endpoint.c  .Module "mod-100rel" unregistered
14:39:36.457 sip_endpoint.c  .Module "mod-ua" unregistered
14:39:36.457 sip_transactio  .Transaction layer module destroyed
14:39:36.457 sip_endpoint.c  .Module "mod-tsx-layer" unregistered
14:39:36.457 sip_endpoint.c  .Module "mod-msg-print" unregistered
14:39:36.457 sip_endpoint.c  .Module "mod-pjsua-log" unregistered
14:39:36.459    udp0x259370  .SIP UDP transport destroyed
14:39:36.460        timer.c  .Dumping timer heap:
14:39:36.460        timer.c  .  Cur size: 0 entries, max: 3070
14:39:36.461 sip_endpoint.c  .Endpoint 0x26af1c destroyed
14:39:36.462   pjsua_core.c  .PJSUA state changed: CLOSING --> NULL
14:39:36.462   pjsua_core.c  .PJSUA destroyed...
@sauwming
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Quite frankly, I'm also not sure why this issue could happen. We only use standard ALSA API calls in alsa_dev, such as snd_pcm_open(), snd_pcm_writei(), etc. So perhaps you could take a look deeper at pjmedia-audiodev/alsa_dev.c to isolate what caused the issue.

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@sauwming @frdskn