This fixes the following bug:
- a source might be copied into the same scene or through a nested scene.
The audio level will then increase by +6 dBFS.
An earlier fix [1] dealt with this bug at the scene audio rendering
level, which leaves some edge cases since the fix is not located
directly in the core audio callback.
The current fix consists in:
- tagging individual sources which appear several times in the audio
tree at each tick;
- promote them to root_nodes sources;
- bypass their mixing in scenes and transitions.
Due to being mixed as root_nodes, the audio of duplicated sources
appears only once in the final audio mix.
[1] https://github.com/obsproject/obs-studio/pull/10537
Signed-off-by: pkv <pkv@obsproject.com>
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