Add PJSUA2 AudioMediaAiPort wrapper for AI media port

[nanangizz]

Summary

Wraps the experimental pjmedia_ai_port (from PR #4866) as a PJSUA2 AudioMedia subclass, enabling C++/Java/Python/C# applications to use the AI media port through the high-level API.

Ref: #4523

Usage

AudioMediaAiPort ai;
ai.createPort();
ai.connect("wss://api.openai.com/v1/realtime?model=...", apiKey);

// Route call audio to/from AI
callMedia.startTransmit(ai);
ai.startTransmit(callMedia);

// Later
ai.disconnect();

Events (connected, transcript, etc.) are delivered via the virtual onEvent() callback, which can be overridden in C++ or target languages via SWIG directors.

Design

• Uses pjsua's SIP endpoint ioqueue and timer heap for WebSocket I/O — no separate worker thread, pjsua's existing worker threads handle polling
• Uses pjmedia_ai_event_type enum directly (no wrapper enum)
• Destructor nulls the user_data back-pointer under grp_lock to prevent use-after-free from in-flight callbacks
• Wrapper pool lifetime tied to grp_lock destroy handler to prevent premature release

Limitations

These are known limitations for reference in future improvements:

• No SSL/TLS parameter configuration (e.g. certificate verification, client certs, cipher suites). The C API supports ssl_param but it is not yet exposed in the PJSUA2 wrapper.
• No way to customize the OpenAI session configuration (voice, instructions, modalities) — currently hardcoded in the backend
• No isConnected() / getState() query method — connection state can only be inferred from onEvent() callbacks
• No JSON persistence (readObject/writeObject) for AiMediaPortParam

Changes

File	Description
pjsip/include/pjsua2/media.hpp	AiMediaEvent, AiMediaPortParam, AudioMediaAiPort class
pjsip/src/pjsua2/media.cpp	Implementation (~120 lines)
pjmedia/include/pjmedia/ai_port.h	Add pjmedia_ai_port_set_user_data()
pjmedia/src/pjmedia/ai_port.c	Implement set_user_data()
pjmedia/include/pjmedia.h	Add ai_port.h to umbrella header
pjsip-apps/src/swig/pjsua2.i	Add director feature for AudioMediaAiPort
pjsip-apps/src/swig/symbols.lst	Add pjmedia_ai_event_type
pjsip-apps/src/swig/symbols.i	Regenerated with importsym2.py
pjsip-apps/src/swig/python/test.py	Python SWIG test for AI port lifecycle + optional OpenAI connection

Test plan

• Build verified on Linux (zero warnings)
• Build on Windows/MSVC (Release-Static, C++ lib clean)
• Python SWIG test: create, conf bridge register, destroy (WSL)
• Python SWIG test with OpenAI connection (requires API key + audio device)

Co-Authored-By: Claude Code

[Copilot]

Pull request overview

This PR exposes the experimental pjmedia_ai_port (AI WebSocket media port) through PJSUA2 by adding an AudioMedia subclass, enabling higher-level language bindings (C++/Java/Python/C#) to connect conference-bridge audio to an AI backend (OpenAI Realtime) and receive events via callbacks.

Changes:

• Add AudioMediaAiPort (PJSUA2) plus AiMediaEvent/AiMediaPortParam types and implement create/connect/disconnect with an OpenAI backend.
• Add pjmedia_ai_port_set_user_data() to support safely clearing the back-pointer during teardown.
• Update SWIG interface/symbol exports so AudioMediaAiPort is director-enabled and pjmedia_ai_event_type is available to bindings.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
pjsip/include/pjsua2/media.hpp	Adds the new PJSUA2 wrapper class and associated parameter/event structs.
pjsip/src/pjsua2/media.cpp	Implements the wrapper, event callback bridging, and teardown logic.
pjmedia/include/pjmedia/ai_port.h	Exposes a new public setter for AI port user data.
pjmedia/src/pjmedia/ai_port.c	Implements the new user-data setter function.
pjmedia/include/pjmedia.h	Pulls ai_port.h into the PJMEDIA umbrella header.
pjsip-apps/src/swig/pjsua2.i	Enables SWIG directors for AudioMediaAiPort callbacks.
pjsip-apps/src/swig/symbols.lst	Exports pjmedia_ai_event_type for SWIG symbol generation.
pjsip-apps/src/swig/symbols.i	Regenerated SWIG symbols to include pjmedia_ai_event_type (and related enum updates).

---

You can also share your feedback on Copilot code review. Take the survey.