Thanks to @ripsaw8080 for insight into CD-DA channel mapping,
@hail-to-the-ryzen for testing and flagging a position-tracking bug,
and @dreamer_ for guidance and code review.
The CD-DA volume and channel mapping loops were moved to generic mixer
calls and no longer require a pre-processing loop:
- Application-controlled CD-DA volume adjustment is now applied using
an existing mixer volume scalar that was previously unused by the
CD-DA code.
- Mapping of CD-DA left and right channels is now applied at the tail
end of the mixer's sample ingest sequence.
The following have been removed:
- The CD-DA callback chunk-wise circular buffer
- The decode buffers in the Opus and MP3 decoders
- The decode buffer and conversion buffers in SDL_Sound
These removals and API changes allow the image player's buffer
to be passed-through ultimately to the audio codec, skipping multiple
intermediate buffers.
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