4.8 KiB
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 1 -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