Audio and video stream refactoring

[sauwming]

In order to support additional media, it would be better to refactor the current implementation of audio and video stream since they contains a lot of duplications, which make code maintenance tedious and more prone to bug (such as if you only fix one stream and do not apply to others).

Scope:

• a new structure pjmedia_stream_common is created as a parent of pjmedia_stream and pjmedia_vid_stream
• a new structure pjmedia_stream_info_common which contains members that exist in bothpjmedia_stream_info and pjmedia_vid_stream_info. Note that unlike the streams (pjmedia_stream and pjmedia_vid_stream) which are opaque, the stream info definition is public, so we cannot modify its internal structure.
• common callbacks for RTP and RTCP handling, on_rx_rtp() and on_rx_rtcp(), which will call its specific stream implementation: on_stream_rx_rtp() (currently no specific stream's RTCP handling).
• common group lock handler on_destroy() which will call its specific stream's handler on_stream_destroy().

Notes:

• Filter RTP based on source address early to avoid invalid RTP session update #2713. The PR was only applied to audio stream, but not video stream. Now both will have the same behavior.
• With this refactoring, the setting PJMEDIA_VID_STREAM_CHECK_RTP_PT now MUST have the same value as PJMEDIA_STREAM_CHECK_RTP_PT. If not, we will print a warning message during compilation and automatically set it to be equal.

[wosrediinanatour]

Cool thing! Has https://github.com/pjsip/pjproject/tree/master/pjsip-apps/src/3rdparty_media_sample been tested?

[wosrediinanatour]

Since there is already a vid_stream.h, I would rename this file to aud_stream.h.
Same for C files: audio_stream.c, audio_stream_info.c

Or even better: audio_stream.h and video_stream.h. Or are there issues with file-name length on any platform?

[sauwming]

Unfortunately this will break app that uses pjmedia directly. App that includes <pjmedia/stream.h> will fail to build. I can make stream.h to include aud_stream.h to avoid the build failure, but then the name of the structs and APIs is still pjmedia_stream instead of pjmedia_aud_stream, so I guess we're stuck with the old naming.

[sauwming]

Cool thing! Has https://github.com/pjsip/pjproject/tree/master/pjsip-apps/src/3rdparty_media_sample been tested?

This PR only modifies pjmedia, and it's done without changing any APIs nor how to use the existing streams (audio and video). So pjsua and application won't be affected.

[sauwming]

The latest commit is to fix failed CI tests.

This is caused by the new API pjmedia_stream_info_common_from_sdp() that can return PJ_SUCCESS, indicating that the SDP is actually valid and as per the specification, that the stream info is initialized, but there's no further processing required. An example of such case is that when the media port is zero.

So, I have to modify the new API to add one more parameter as an output param.