mirror of
https://github.com/irmen/prog8.git
synced 2024-11-27 03:50:27 +00:00
205 lines
6.3 KiB
Lua
205 lines
6.3 KiB
Lua
%import textio
|
|
%import floats
|
|
%option no_sysinit
|
|
%zeropage basicsafe
|
|
|
|
;
|
|
; IMA ADPCM decoding and playback example.
|
|
; https://wiki.multimedia.cx/index.php/IMA_ADPCM
|
|
; https://wiki.multimedia.cx/index.php/Microsoft_IMA_ADPCM
|
|
;
|
|
; IMA ADPCM encodes two 16-bit PCM audio samples in 1 byte (1 word per nibble)
|
|
; thus compressing the audio data by a factor of 4.
|
|
; The encoding precision is about 13 bits per sample so it's a lossy compression scheme.
|
|
;
|
|
; NOTE: this program requires 16 bits MONO audio, and 256 byte encoded block size!
|
|
; HOW TO CREATE SUCH IMA-ADPCM ENCODED AUDIO? Use sox or ffmpeg:
|
|
; $ sox --guard source.mp3 -r 8000 -c 1 -e ima-adpcm out.wav trim 01:27.50 00:09
|
|
; $ ffmpeg -i source.mp3 -ss 00:01:27.50 -to 00:01:36.50 -ar 8000 -ac 1 -c:a adpcm_ima_wav -block_size 256 -map_metadata -1 -bitexact out.wav
|
|
;
|
|
; THEN use a tool to read the raw audio frame data from that resulting out.wav and save it as 'adpcm-mono.bin'.
|
|
;
|
|
|
|
main {
|
|
|
|
ubyte num_adpcm_blocks
|
|
ubyte adpcm_blocks_left
|
|
uword @requirezp nibblesptr
|
|
|
|
sub start() {
|
|
uword adpcm_size = &audiodata.adpcm_data_end - &audiodata.adpcm_data
|
|
num_adpcm_blocks = (adpcm_size / 256) as ubyte ; NOTE: THE ADPCM DATA NEEDS TO BE ENCODED IN 256-byte BLOCKS !
|
|
|
|
txt.print_uw(adpcm_size)
|
|
txt.print(" adpcm data size = ")
|
|
txt.print_ub(num_adpcm_blocks)
|
|
txt.print(" blocks\n(b)enchmark or (p)layback? ")
|
|
|
|
when c64.CHRIN() {
|
|
'b' -> benchmark()
|
|
'p' -> playback()
|
|
}
|
|
}
|
|
|
|
sub benchmark() {
|
|
nibblesptr = &audiodata.adpcm_data
|
|
|
|
txt.print("\ndecoding all blocks...\n")
|
|
c64.SETTIM(0,0,0)
|
|
repeat num_adpcm_blocks {
|
|
adpcm.init(peekw(nibblesptr), @(nibblesptr+2))
|
|
nibblesptr += 4
|
|
repeat 252 {
|
|
ubyte @zp nibble = @(nibblesptr)
|
|
adpcm.decode_nibble(nibble & 15) ; first word
|
|
adpcm.decode_nibble(nibble>>4) ; second word
|
|
nibblesptr++
|
|
}
|
|
}
|
|
float duration_secs = (c64.RDTIM16() as float) / 60.0
|
|
float words_per_second = 505.0 * (num_adpcm_blocks as float) / duration_secs
|
|
txt.print_uw(words_per_second as uword)
|
|
txt.print(" words/sec\n")
|
|
}
|
|
|
|
sub playback() {
|
|
nibblesptr = &audiodata.adpcm_data
|
|
adpcm_blocks_left = num_adpcm_blocks
|
|
|
|
cx16.VERA_AUDIO_CTRL = %10101111 ; mono 16 bit
|
|
cx16.VERA_AUDIO_RATE = 0 ; halt playback
|
|
repeat 1024 {
|
|
cx16.VERA_AUDIO_DATA = 0
|
|
}
|
|
|
|
sys.set_irqd()
|
|
cx16.CINV = &irq_handler
|
|
cx16.VERA_IEN = %00001000 ; enable AFLOW
|
|
sys.clear_irqd()
|
|
|
|
cx16.VERA_AUDIO_RATE = 21 ; start playback at ~8000 hz
|
|
|
|
float rate = (cx16.VERA_AUDIO_RATE as float) * (25e6 / 65536.0)
|
|
txt.print("\naudio via irq at ")
|
|
txt.print_uw(rate as uword)
|
|
txt.print(" hz mono\n")
|
|
|
|
repeat {
|
|
; audio will play via the IRQ.
|
|
}
|
|
|
|
; not reached:
|
|
; cx16.VERA_AUDIO_CTRL = %00100000
|
|
; cx16.VERA_AUDIO_RATE = 0
|
|
; txt.print("audio off.\n")
|
|
}
|
|
|
|
sub irq_handler() {
|
|
if cx16.VERA_ISR & %00001000 {
|
|
; AFLOW irq.
|
|
;; cx16.vpoke(1,$fa0c, $a0) ; paint a screen color
|
|
|
|
; refill the fifo buffer with two decoded adpcm blocks (252 nibbles -> 1008 bytes per block)
|
|
repeat 2 {
|
|
adpcm.init(peekw(nibblesptr), @(nibblesptr+2))
|
|
nibblesptr += 4
|
|
repeat 252 {
|
|
ubyte @zp nibble = @(nibblesptr)
|
|
adpcm.decode_nibble(nibble & 15) ; first word
|
|
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict)
|
|
cx16.VERA_AUDIO_DATA = msb(adpcm.predict)
|
|
adpcm.decode_nibble(nibble>>4) ; second word
|
|
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict)
|
|
cx16.VERA_AUDIO_DATA = msb(adpcm.predict)
|
|
nibblesptr++
|
|
}
|
|
|
|
adpcm_blocks_left--
|
|
if adpcm_blocks_left==0 {
|
|
; restart adpcm data from the beginning
|
|
nibblesptr = &audiodata.adpcm_data
|
|
adpcm_blocks_left = num_adpcm_blocks
|
|
}
|
|
}
|
|
|
|
} else {
|
|
; TODO not AFLOW, handle other IRQ
|
|
}
|
|
|
|
;; cx16.vpoke(1,$fa0c, 0) ; back to other screen color
|
|
|
|
%asm {{
|
|
ply
|
|
plx
|
|
pla
|
|
rti
|
|
}}
|
|
}
|
|
|
|
}
|
|
|
|
adpcm {
|
|
|
|
; IMA ADPCM decoder.
|
|
; https://wiki.multimedia.cx/index.php/IMA_ADPCM
|
|
; https://wiki.multimedia.cx/index.php/Microsoft_IMA_ADPCM
|
|
|
|
ubyte[] t_index = [ -1, -1, -1, -1, 2, 4, 6, 8, -1, -1, -1, -1, 2, 4, 6, 8]
|
|
uword[] t_step = [
|
|
7, 8, 9, 10, 11, 12, 13, 14,
|
|
16, 17, 19, 21, 23, 25, 28, 31,
|
|
34, 37, 41, 45, 50, 55, 60, 66,
|
|
73, 80, 88, 97, 107, 118, 130, 143,
|
|
157, 173, 190, 209, 230, 253, 279, 307,
|
|
337, 371, 408, 449, 494, 544, 598, 658,
|
|
724, 796, 876, 963, 1060, 1166, 1282, 1411,
|
|
1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
|
|
3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
|
|
7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
|
|
15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794,
|
|
32767]
|
|
|
|
uword @zp predict
|
|
ubyte @zp index
|
|
uword @zp pstep
|
|
|
|
sub init(uword startPredict, ubyte startIndex) {
|
|
predict = startPredict
|
|
index = startIndex
|
|
pstep = t_step[index]
|
|
}
|
|
|
|
sub decode_nibble(ubyte nibble) {
|
|
; this is the hotspot of the decoder algorithm!
|
|
cx16.r0s = 0 ; difference
|
|
if nibble & %0100
|
|
cx16.r0s += pstep
|
|
pstep >>= 1
|
|
if nibble & %0010
|
|
cx16.r0s += pstep
|
|
pstep >>= 1
|
|
if nibble & %0001
|
|
cx16.r0s += pstep
|
|
pstep >>= 1
|
|
cx16.r0s += pstep
|
|
if nibble & %1000
|
|
cx16.r0s = -cx16.r0s
|
|
predict += cx16.r0s as uword
|
|
index += t_index[nibble]
|
|
if index & 128
|
|
index = 0
|
|
else if index > len(t_step)-1
|
|
index = len(t_step)-1
|
|
pstep = t_step[index]
|
|
}
|
|
}
|
|
|
|
|
|
audiodata {
|
|
%option align_page
|
|
adpcm_data:
|
|
%asmbinary "adpcm-mono.bin"
|
|
adpcm_data_end:
|
|
|
|
}
|