64 lines
2.3 KiB
Markdown
64 lines
2.3 KiB
Markdown
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`.
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It was edited to fix typos, have a hopefully better code organization with hopefully more usefull variable names.
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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.
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In this instance, it's used to determine the coordinates of a few primitives to display a [VU-meter](https://en.wikipedia.org/wiki/VU_meter).
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This technique is known to be used in certain games for lipsynching or audio visualization ( Crash team racing, Hercules, Vib Ribbon ...).
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## pcsx-redux : no animation
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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.
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If looking for an alternative, check [duckstation](https://www.duckstation.org/) out.
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## PsyQ's SpuReadDecodedData() doc errata
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The main function for transferring data from the SPU to the RAM is `SpuReadDecodedData()`, and is documented in **LibRef47.pdf, p1054**.
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The table on this page (Table 15-2) contains erroneous data and should read :
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The correct address ranges for the SPU buffer is :
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| Map (bytes) | Data contents |
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|-------------|---------------|
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| 0x000 - 0x3ff | CD Left channel |
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| 0x400 - 0x7ff | CD Right channel |
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| 0x800 - 0xbff | Voice 1 |
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| 0xC00 - 0xfff | Voice 3 |
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## Compiling
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You need [mkpsxiso](https://github.com/Lameguy64/mkpsxiso) in your $PATH to generate a PSX disk image.
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Typing
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```bash
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make
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```
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in a terminal will compile and generate the bin/cue files.
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Typing
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```bash
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make cleansub
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```
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will clean the current directory
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## More on CDDA
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See the [hello_cdda](https://github.com/ABelliqueux/nolibgs_hello_worlds/tree/main/hello_cdda) example in this repo.
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## Docs and links
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Original psyq example : `psyq/psx/sample/sound/CDVOL, main.c,v 1.14 1997/05/02 13:05:21 by ayako`
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## Music credits
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Track 1 :
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Beach Party by Kevin MacLeod
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Link: https://incompetech.filmmusic.io/song/3429-beach-party
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License: https://filmmusic.io/standard-license
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Track 2:
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Funk Game Loop by Kevin MacLeod
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Link: https://incompetech.filmmusic.io/song/3787-funk-game-loop
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License: https://filmmusic.io/standard-license
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