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prog8/examples/cx16/pcmaudio/play-adpcm.p8

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%import textio
%import floats
%import wavfile
%import adpcm
%option no_sysinit
%zeropage basicsafe
;
; Simple IMA ADPCM playback example. (factor 4 lossy compressed pcm audio)
;
; NOTE: this program requires 16 bits MONO or STEREO 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
; Or use a tool such as https://github.com/dbry/adpcm-xq (make sure to set correct block size)
;
main {
ubyte adpcm_blocks_left
uword vera_rate_hz
ubyte vera_rate
ubyte num_adpcm_blocks
uword adpcm_size
uword @requirezp nibblesptr
sub start() {
if not wavfile.parse_header(&wavdata.wav_data) {
txt.print("invalid wav\n")
sys.exit(1)
}
calculate_vera_rate()
calculate_adpcm_blocks()
txt.print_ub(num_adpcm_blocks)
txt.print(" blocks = ")
txt.print_uw(adpcm_size)
txt.print(" adpcm bytes\nsamplerate = ")
txt.print_uw(wavfile.sample_rate)
txt.print(" vera rate = ")
txt.print_uw(vera_rate_hz)
txt.print(" #channels = ")
txt.print_ub(wavfile.nchannels)
txt.print("\n\n(b)enchmark or (p)layback? ")
when cbm.CHRIN() {
'b' -> {
cbm.SETTIM(0,0,0)
when wavfile.nchannels {
1-> {
mono.benchmark()
decoding_report(1 + 252*2)
}
2-> {
stereo.benchmark()
decoding_report(2 + 248*4)
}
}
}
'p' -> playback()
}
}
sub calculate_vera_rate() {
const float vera_freq_factor = 25e6 / 65536.0
vera_rate = (wavfile.sample_rate as float / vera_freq_factor) + 1.0 as ubyte
vera_rate_hz = (vera_rate as float) * vera_freq_factor as uword
}
sub calculate_adpcm_blocks() {
adpcm_size = wavfile.data_size_lo ; we assume the data is <64Kb so only low word is enough
num_adpcm_blocks = (adpcm_size / 256) as ubyte ; THE ADPCM DATA NEEDS TO BE ENCODED IN 256-byte BLOCKS !
}
sub decoding_report(float pcm_words_per_block) {
const float REFRESH_RATE = 25.0e6/(525.0*800) ; Vera VGA refresh rate is not precisely 60 hz!
float duration_secs = (cbm.RDTIM16() as float) / REFRESH_RATE
floats.print(duration_secs)
txt.print(" seconds (approx)\n")
float src_per_second = adpcm_size as float / duration_secs
txt.print_uw(src_per_second as uword)
txt.print(" adpcm data bytes/sec\n")
float words_per_second = pcm_words_per_block * (num_adpcm_blocks as float) / duration_secs
when wavfile.nchannels {
1 -> {
txt.print_uw(words_per_second as uword)
txt.print(" decoded mono pcm words/sec (max hz)\n")
}
2 -> {
txt.print_uw(words_per_second as uword)
txt.print(" decoded pcm words/sec\n")
txt.print_uw(words_per_second/2 as uword)
txt.print(" decoded stereo audio frames/sec (max hz)\n")
}
}
}
sub playback() {
nibblesptr = &wavdata.wav_data + wavfile.data_offset
adpcm_blocks_left = num_adpcm_blocks
sys.set_irqd()
cx16.VERA_AUDIO_RATE = 0 ; halt playback
repeat 1024 {
cx16.VERA_AUDIO_DATA = 0
}
when wavfile.nchannels {
1 -> {
cx16.VERA_AUDIO_CTRL = %10101011 ; mono 16 bit, volume 11
cbm.CINV = &mono.irq_handler
}
2 -> {
cx16.VERA_AUDIO_CTRL = %10111011 ; stereo 16 bit, volume 11
cbm.CINV = &stereo.irq_handler
}
}
cx16.VERA_IEN = %00001000 ; enable AFLOW
sys.clear_irqd()
cx16.VERA_AUDIO_RATE = vera_rate ; start playback
txt.print("\naudio via irq\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")
}
}
mono {
sub benchmark() {
main.nibblesptr = &wavdata.wav_data + wavfile.data_offset
txt.print("\ndecoding all blocks...\n")
repeat main.num_adpcm_blocks
decode_block()
}
sub decode_block() {
; refill the fifo buffer with one decoded adpcm block (1010 bytes of pcm data)
adpcm.init(peekw(main.nibblesptr), @(main.nibblesptr+2))
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict)
cx16.VERA_AUDIO_DATA = msb(adpcm.predict)
main.nibblesptr += 4
ubyte @zp nibble
repeat 252/2 {
unroll 2 {
nibble = @(main.nibblesptr)
adpcm.decode_nibble(nibble & 15) ; first word (note: upper nibble needs to be zero!)
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict)
cx16.VERA_AUDIO_DATA = msb(adpcm.predict)
adpcm.decode_nibble(nibble>>4) ; second word (note: upper nibble is zero, after the shifts.)
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict)
cx16.VERA_AUDIO_DATA = msb(adpcm.predict)
main.nibblesptr++
}
}
}
sub irq_handler() {
if cx16.VERA_ISR & %00001000 !=0 {
; AFLOW irq.
;; cx16.vpoke(1,$fa0c, $a0) ; paint a screen color
decode_block()
main.adpcm_blocks_left--
if main.adpcm_blocks_left==0 {
; restart adpcm data from the beginning
main.nibblesptr = &wavdata.wav_data + wavfile.data_offset
main.adpcm_blocks_left = main.num_adpcm_blocks
txt.print("end of data, restarting.\n")
}
} else {
; it's not AFLOW, handle other IRQ here.
}
;; cx16.vpoke(1,$fa0c, 0) ; back to other screen color
%asm {{
ply
plx
pla
rti
}}
}
}
stereo {
sub benchmark() {
main.nibblesptr = &wavdata.wav_data + wavfile.data_offset
txt.print("\n\ndecoding all blocks...\n")
repeat main.num_adpcm_blocks
decode_block()
}
sub decode_block() {
; refill the fifo buffer with one decoded adpcm block (1010 bytes of pcm data)
adpcm.init(peekw(main.nibblesptr), @(main.nibblesptr+2)) ; left channel
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict)
cx16.VERA_AUDIO_DATA = msb(adpcm.predict)
adpcm.init_second(peekw(main.nibblesptr+4), @(main.nibblesptr+6)) ; right channel
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict_2)
cx16.VERA_AUDIO_DATA = msb(adpcm.predict_2)
main.nibblesptr += 8
repeat 248/8
decode_nibbles_unrolled()
}
sub decode_nibbles_unrolled() {
; decode 4 left channel nibbles
; note: when calling decode_nibble(), the upper nibble in the argument needs to be zero
uword[8] left
uword[8] right
ubyte @requirezp nibble = @(main.nibblesptr)
adpcm.decode_nibble(nibble & 15) ; first word
left[0] = adpcm.predict
adpcm.decode_nibble(nibble>>4) ; second word
left[1] = adpcm.predict
nibble = @(main.nibblesptr+1)
adpcm.decode_nibble(nibble & 15) ; first word
left[2] = adpcm.predict
adpcm.decode_nibble(nibble>>4) ; second word
left[3] = adpcm.predict
nibble = @(main.nibblesptr+2)
adpcm.decode_nibble(nibble & 15) ; first word
left[4] = adpcm.predict
adpcm.decode_nibble(nibble>>4) ; second word
left[5] = adpcm.predict
nibble = @(main.nibblesptr+3)
adpcm.decode_nibble(nibble & 15) ; first word
left[6] = adpcm.predict
adpcm.decode_nibble(nibble>>4) ; second word
left[7] = adpcm.predict
; decode 4 right channel nibbles
nibble = @(main.nibblesptr+4)
adpcm.decode_nibble_second(nibble & 15) ; first word
right[0] = adpcm.predict_2
adpcm.decode_nibble_second(nibble>>4) ; second word
right[1] = adpcm.predict_2
nibble = @(main.nibblesptr+5)
adpcm.decode_nibble_second(nibble & 15) ; first word
right[2] = adpcm.predict_2
adpcm.decode_nibble_second(nibble>>4) ; second word
right[3] = adpcm.predict_2
nibble = @(main.nibblesptr+6)
adpcm.decode_nibble_second(nibble & 15) ; first word
right[4] = adpcm.predict_2
adpcm.decode_nibble_second(nibble>>4) ; second word
right[5] = adpcm.predict_2
nibble = @(main.nibblesptr+7)
adpcm.decode_nibble_second(nibble & 15) ; first word
right[6] = adpcm.predict_2
adpcm.decode_nibble_second(nibble>>4) ; second word
right[7] = adpcm.predict_2
main.nibblesptr += 8
%asm {{
; copy to vera PSG fifo buffer
ldy #0
- lda p8v_left,y
sta cx16.VERA_AUDIO_DATA
lda p8v_left+1,y
sta cx16.VERA_AUDIO_DATA
lda p8v_right,y
sta cx16.VERA_AUDIO_DATA
lda p8v_right+1,y
sta cx16.VERA_AUDIO_DATA
iny
iny
cpy #16
bne -
}}
}
sub irq_handler() {
if cx16.VERA_ISR & %00001000 !=0 {
; AFLOW irq.
;; cx16.vpoke(1,$fa0c, $a0) ; paint a screen color
decode_block()
main.adpcm_blocks_left--
if main.adpcm_blocks_left==0 {
; restart adpcm data from the beginning
main.nibblesptr = &wavdata.wav_data + wavfile.data_offset
main.adpcm_blocks_left = main.num_adpcm_blocks
txt.print("end of data, restarting.\n")
}
} else {
; it's not AFLOW, handle other IRQ here.
}
;; cx16.vpoke(1,$fa0c, 0) ; back to other screen color
%asm {{
ply
plx
pla
rti
}}
}
}
wavdata {
wav_data:
%asmbinary "small-adpcm-mono.wav"
wav_data_end:
}
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