Signal PJMEDIA_EVENT_AUD_DEV_ERROR on audio device failures

[Copilot]

Description

Audio device play/record failures were not consistently signaled across implementations. Only WMME and Oboe published PJMEDIA_EVENT_AUD_DEV_ERROR events, and pjsua_ext_snd_dev did not subscribe to these events.

Changes

Added event publishing to audio device backends:

• ALSA (alsa_dev.c): Publish events in playback/capture thread error paths
• PortAudio (pa_dev.c): Publish events in recorder/playback callbacks before returning paAbort
• OpenSL ES (opensl_dev.c): Publish events on callback failures and buffer enqueue errors
• Android JNI (android_jni_dev.c): Publish events in recorder/track callback error paths
• CoreAudio (coreaudio_dev.m): Publish events in input/output renderer callbacks

Made pjsua_ext_snd_dev subscribe to events:

• Subscribe in pjsua_ext_snd_dev_create() after sound device connection
• Unsubscribe in pjsua_ext_snd_dev_destroy() before sound port destruction

All implementations follow the existing pattern from WMME/Oboe:

pjmedia_event_init(&e, PJMEDIA_EVENT_AUD_DEV_ERROR, &timestamp, &stream->base);
e.data.aud_dev_err.dir = PJMEDIA_DIR_PLAYBACK; // or PJMEDIA_DIR_CAPTURE
e.data.aud_dev_err.status = status;
e.data.aud_dev_err.id = device_id;
pjmedia_event_publish(NULL, &stream->base, &e, PJMEDIA_EVENT_PUBLISH_DEFAULT);

Events are only published on actual errors, not during normal shutdown (quit_flag check).

Motivation and Context

Applications using on_media_event() callback receive audio device errors inconsistently depending on which backend is active. This makes error handling unreliable across platforms.

How Has This Been Tested?

• Built successfully on Linux with null audio device
• Verified PJSUA starts without errors: ./pjsua-x86_64-pc-linux-gnu --null-audio --no-cli-console
• Code follows existing WMME/Oboe implementation patterns

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the CODING STYLE of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Signal PJMEDIA_EVENT_AUD_DEV_ERROR upon sound device play/record failure in any audio device</issue_title>
<issue_description>### Describe the feature

Currently WMME (pjmedia/src/pjmedia-audiodev/wmme_dev.c) and Oboe (pjmedia/src/pjmedia-audiodev/oboe_dev.cpp) publish media event PJMEDIA_EVENT_AUD_DEV_ERROR when sound device play/record failures occur. The pjsua-lib then receives the event and forwards it to app via the on_media_event() callback.

However, there are two issues:

1. Not all audio device implementations in pjmedia/src/pjmedia-audiodev publish this event.
2. The extra sound device (pjsua_ext_snd_dev) does not subscribe to the event so it cannot forward it via on_media_event() callback.

Describe alternatives you've considered

No response

Additional context

No response</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Signal PJMEDIA_EVENT_AUD_DEV_ERROR upon sound device play/record failure in any audio device #4753

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