Add cross-platform support and fix logging issues

[davegullo]

Changes

• Make hang library import cross-platform in CMakeLists.txt (supports .dylib on macOS, .so on Unix/Linux, .dll on Windows)
• Fix printf format specifiers for int64_t using PRId64 macro
• Fix ConfigureVideoTrack logging bug (video_width was missing)

Building

Built on Ubuntu 24.04.3 LTS

#!/bin/bash
cmake --preset ubuntu-x86_64
cmake --build --preset ubuntu-x86_64
cp build_x86_64/obs-moq.so ~/.config/obs-studio/plugins/obs-moq/bin/64bit/obs-moq.so

Caveats

Trying to build with ENABLE_FRONTEND_API fails with this message (even though libobs-dev is installed via sudo apt install -y libobs-dev )

CMake Error in CMakeLists.txt:
  IMPORTED_LOCATION or IMPORTED_IMPLIB not set for imported target
  "OBS::obs-frontend-api" configuration "RelWithDebInfo".

The workaround instead of using the UI to setup your service is to just put it here:

$ cat ~/.config/obs-studio/basic/profiles/Untitled/service.json
   {
       "type": "moq_service",
       "settings": {
           "server": "https://my-foo-service:4443",
           "key": "obs-test/obs-test"
       }
   }

Make sure you have the latest moq relay built, and then if you have built hang-gst you can watch it with:

#!/bin/bash
gst-launch-1.0 \
  hangsrc url=https://my-foo-service:4443/obs-test broadcast=obs-test ! \
  h264parse ! \
  nvh264dec ! \
  nv3dsink

... or pick your favorite method.

[emilsas]

Thanks for the PR! LGTM, there are some conflicts to fix before merging.

[davegullo]

NOTE, converted this to a draft, as there are a few open and unresolved items.

Currently, this happens when building:

In file included from /root/src/obs-moq/src/moq-output.h:5,
                 from /root/src/obs-moq/src/moq-output.cpp:4:
/root/src/obs-moq/src/moq-output.cpp: In member function 'void MoQOutput::ConfigureVideoTrack()':
/root/src/obs-moq/src/moq-output.cpp:146:49: error: 'obs_data_get_json_pretty_with_defaults' was not declared in this scope
  146 |         LOG_DEBUG("Video encoder settings: %s", obs_data_get_json_pretty_with_defaults(settings));
      |                                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/root/src/obs-moq/src/logger.h:4:68: note: in definition of macro 'LOG'
    4 | #define LOG(level, format, ...) blog(level, "[obs-moq] " format, ##__VA_ARGS__)
      |                                                                    ^~~~~~~~~~~
/root/src/obs-moq/src/moq-output.cpp:146:9: note: in expansion of macro 'LOG_DEBUG'
  146 |         LOG_DEBUG("Video encoder settings: %s", obs_data_get_json_pretty_with_defaults(settings));
      |         ^~~~~~~~~
/root/src/obs-moq/src/moq-output.cpp: In member function 'void MoQOutput::ConfigureAudioTrack()':
/root/src/obs-moq/src/moq-output.cpp:173:49: error: 'obs_data_get_json_pretty_with_defaults' was not declared in this scope
  173 |         LOG_DEBUG("Audio encoder settings: %s", obs_data_get_json_pretty_with_defaults(settings));
      |                                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/root/src/obs-moq/src/logger.h:4:68: note: in definition of macro 'LOG'
    4 | #define LOG(level, format, ...) blog(level, "[obs-moq] " format, ##__VA_ARGS__)
      |                                                                    ^~~~~~~~~~~
/root/src/obs-moq/src/moq-output.cpp:173:9: note: in expansion of macro 'LOG_DEBUG'
  173 |         LOG_DEBUG("Audio encoder settings: %s", obs_data_get_json_pretty_with_defaults(settings));
      |         ^~~~~~~~~

Therefore this is why this patch exists:
https://github.com/qualabs/obs-moq/pull/4/files#diff-6fa2e928ec9e97965c6bf1c68ee9142e31d4b0761e04ea74ec7d351987ef90ebR173

Once this PR is applied, it builds. But then when running, we get this at runtime in the OBS logs:

error: os_dlopen(/home/ubuntu/.config/obs-studio/plugins/obs-moq/bin/64bit/obs-moq.so->/home/ubuntu/.config/obs-studio/plugins/obs-moq/bin/64bit/obs-moq.so): /home/ubuntu/.config/obs-studio/plugins/obs-moq/bin/64bit/obs-moq.so: undefined symbol: hang_write_audio_packet_from_c

I believe this is an open issue, so I'm waiting for this to be resolved before moving forward with more testing.