2.3 KiB
This example is adapted from PsyQ's sample : psyq/psx/sample/sound/CDVOL, main.c,v 1.14 1997/05/02 13:05:21 by ayako.
It was edited to fix typos, have a hopefully better code organization with hopefully more usefull variable names.
What it does is demonstrate how to transfer data from the PSX 's SPU to main memory in order to analyze / process the audio signal and dostuff accordingly.
In this instance, it's used to determine the coordinates of a few primitives to display a VU-meter.
This technique is known to be used in certain games for lipsynching or audio visualization ( Crash team racing, Hercules, Vib Ribbon ...).
pcsx-redux : no animation
Pcsx-redux does not yet support these specific SPU buffers nor triggerring IRQ from them so as of 11-2021 this example doesn't work in this particular emulator.
If looking for an alternative, check duckstation out.
PsyQ's SpuReadDecodedData() doc errata
The main function for transferring data from the SPU to the RAM is SpuReadDecodedData(), and is documented in LibRef47.pdf, p1054.
The table on this page (Table 15-2) contains erroneous data and should read :
The correct address ranges for the SPU buffer is :
| Map (bytes) | Data contents |
|---|---|
| 0x000 - 0x3ff | CD Left channel |
| 0x400 - 0x7ff | CD Right channel |
| 0x800 - 0xbff | Voice 1 |
| 0xC00 - 0xfff | Voice 3 |
Compiling
You need mkpsxiso in your $PATH to generate a PSX disk image. Typing
make
in a terminal will compile and generate the bin/cue files.
Typing
make cleansub
will clean the current directory
More on CDDA
See the hello_cdda example in this repo.
Docs and links
Original psyq example : psyq/psx/sample/sound/CDVOL, main.c,v 1.14 1997/05/02 13:05:21 by ayako
Music credits
Track 1 : Beach Party by Kevin MacLeod Link: https://incompetech.filmmusic.io/song/3429-beach-party License: https://filmmusic.io/standard-license
Track 2: Funk Game Loop by Kevin MacLeod Link: https://incompetech.filmmusic.io/song/3787-funk-game-loop License: https://filmmusic.io/standard-license