nolibgs_hello_worlds/hello_multi_xa/README.md

Multi XA samples playback

Use an interleaved XA file to store multiple sound effects and use pre-calculated offset to play them back.
Use up, down, left, right, triangle, cross, circle, square to play various samples.

If this seems complicated, first study the simple XA playback example : https://github.com/ABelliqueux/nolibgs_hello_worlds/tree/main/hello_xa

You need mkpsxiso in your $PATH to generate a PSX disk image. You also need ffmpeg, psxavenc and xainterleave.

Compile

This will compile and build an iso image :

make

Clean directory

make cleansub

Producing an interleaved XA sound bank

Sound to WAV conversion with ffmpeg

ffmpeg -i input.mp3 -acodec pcm_s16le -ac 2 -ar 44100 output.wav

WAV to XA conversion

See further down how you should adapt the -F and -C parameters.

psxavenc -f 37800 -t xa -b 4 -c 2 -F 1 -C 0 input.wav output.xa

XA to multi XA track

You can use a concatenation tool to build your tracks like so :

cat track1.xa track2.xa track3.xa > channelX.xa

On windows, use :

copy track1.xa+track2.xa+track3.xa channelX.xa

XA to interleaved XA

Use xainterleave as instructed here : https://github.com/ABelliqueux/nolibgs_hello_worlds/wiki/XA#interleaving-xa-files

Multi XA specifics

Silence file

You should use a silent XA file to intersperse between your samples, so that you have a margin of error to avoid pops and noises.I.e:

cat track1.xa silence.xa track3.xa silence.xa track4.xa  > channelX.xa

XA file size and vertical density

An interleaved XA (4 or 8 channels) file will have the size of its largest channel multiplied by the number of channels.
Therefore, you should try to obtain a vertical density on all channels for your sample, i.e :

That :

channel 0   sample1.xa
channel 1   sample2.xa
channel 2   sample3.xa
channel 3   sample4.xa

instead of :

channel 0   sample1.xa sample2.xa sample2.xa sample4.xa
channel 1   
channel 2   
channel 3   

You should use your longest sample as a base duration, and create the other channels to obtain a similar duration, i.e :

channel 0   <------------- sample1.xa ---------------> <-- silence.xa --> <-sample2.xa ->
channel 1   <-- sample3.xa --> <-- silence.xa --> < -------- sample4.xa ----------->

Calculating sample's start and end offsets

Using the size of your XA sample file, you can find it's size in sector like so :

(size/2336)-1 * 8

For example, file with size 84096B is (((84096/2336) == 36) - 1 == 35) * 8 == 280.

First sample's start will then be 0, and end 280. The following sample's start position will have an offset of 8, hence 288, etc.

Example

These are the calculations for the files on 4 channels

// channel 1
// name       size  start end
5_come.xa    18688  0      56
5_sile_h.xa  23360  64     136     
5_erro.xa    44384  144    288
 
// channel 2
6_cuek.xa    32704  0      104
6_sile_h.xa  23360  112    184
6_hehe.xa    56064  196    380
6_sile_h.xa  23360  388    460
6_wron.xa    53728  468    644

// channel 3
7_m4a1.xa    84096  0      280
7_sile_h.xa  23360  288    360 
7_punch.xa   16352  368    416

// channel 4
8_yooo.xa    114464 0      384

and the corresponding structure in code :

XAbank soundBank = {
        8, // index
        0, // file offset
        {
            // channel 5
            // id   size   file  channel start end cursor
            {   0,  18688,   0,     5,     0,   56,  -1 }, 
            // Ommit the silence.xa file
            {   1,  44384,   0,     5 ,   144,  288, -1 }, 
            // channel 6                 
            {   2,  32704,   0,     6 ,   0,   104, -1  }, 
            // Ommit the silence.xa file
            {   3,  56064,   0,     6 ,   196, 380, -1  }, 
            // Ommit the silence.xa file
            {   4,  53728,   0,     6 ,   468, 644, -1  }, 
            // channel 7                               
            {   5,  84096,   0,     7 ,   0,   260, -1  }, 
            // Ommit the silence.xa file
            {   6,  16352,   0,     7 ,   368, 440, -1  }, 
            // channel 8                               
            {  7,  114464,   0,     8 ,   0,   384, -1  }
        }
};

Tools, sources and documentation

See the wiki for general informations, tools and sources about the XA format : https://github.com/ABelliqueux/nolibgs_hello_worlds/wiki/XA

Sound credits

All the sound effects come from https://www.myinstants.com and are :

comedy_pop_finger_in_mouth_001(1).mp3
cuek.swf.mp3
erro.mp3
m4a1_single-kibblesbob-8540445.mp3
punch.mp3
wrong-answer-sound-effect.mp3
yooooooooooooooooooooooooo_4.mp3
hehehehhehehehhehehheheehehe.mp3