Schrijver
| PCM player using SCC
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ARTRAG
msx master
Berichten: 1737 |  Geplaatst: 21 Oktober 2007, 23:23 |
You have mail
this is the new release according to latest info
;----------------------------------------------------------------------------
;----------------------------------------------------------------------------
OUTPUT sccplay.rom
org 4000h
dw "BA",START,0,0,0,0,0,0
Bank1 equ 05000h
Bank2 equ 07000h
Bank3 equ 09000h
Bank4 equ 0B000h
;-------------------------------------
; Entry point
;-------------------------------------
START:
call powerup
xor a
call 005Fh
ld a,3Fh
LD (Bank3),A
Period equ 9
; F sample = 3,579,545Hz / 32 / (1+Period)
; F rotation = 32 * F sample;
ld hl,Period ; F sample ch1 = 11186Hz
ld (9880h),hl
ld hl,32*Period+31 ; F sample ch4 = F sample ch1/32
ld (9886h),hl
DISPLAY "Period of ch 1 is :",/D,Period
DISPLAY "Period of ch 4 is :",/D,32*Period+31
ld a,15
ld (988Ah),a ; volume ch1
xor a
ld (988Bh),a ; volume ch2
ld (988Ch),a ; volume ch3
ld (988Dh),a ; volume ch4
ld (988Eh),a ; volume ch5
ld a,00011111b ; ALL channels active
ld (988Fh),a
ld hl,9800h+32*3 ; counter in channel 4
ld bc,32*256
.counter:
ld (hl),c
inc hl
inc c
djnz .counter
;RRB000XX
ld a,10000000b ; Rotate only CH4 & CH5 common waveform. Waveform will be rotated with CH4 freq.
ld (98E0h),a
.REWIND:
xor a
.LOOP:
inc a
ld (Bank2),a
ld hl, SAMPLE_START
ex af,af'
ld b,0
.page:
push bc
;;;;;;;;;;;;;;;;;;;;;;
;
; do your stuff here
; in less than 32 / F_sample ch1 seconds
; but in more than 1 / F_sample ch1 seconds
ld b,170
.inner
ld a,r
out(99h),a
ld a,128+7
out(99h),a
djnz .inner
;
;;;;;;;;;;;;;;;;;;;;;;
.wait:
ld a,(9800h+32*3)
or a
jr nz,.wait ; wait for a complete rotation on ch 4
ld de,9800h ; wavetable ch1
ld bc,20h
ldir
pop bc
djnz .page
ex af,af'
cp (SAMPLE_END - SAMPLE_START + #1FFF)/#2000
jr nz,.LOOP
jr .REWIND
ret
;-------------------------------------
; Powerup routine for non-Z180 code.
; set pages and subslot
;-------------------------------------
powerup:
call 0x138
rrca
rrca
and 0x03
ld c,a
ld b,0
ld hl,0xfcc1
add hl,bc
or (hl)
ld b,a
inc hl
inc hl
inc hl
inc hl
ld a,(hl)
and 0x0c
or b
ld h,0x80
call 0x24
ret
;-------------------------------------
; Padding for rom player
;-------------------------------------
DS (#6000 - $)
;-------------------------------------
; Sample data
;-------------------------------------
SAMPLE_START:
incbin "handel3.wav",44, 56*1024
SAMPLE_END:
;-------------------------------------
; Padding, align rom image to a power of two.
;-------------------------------------
SAMPLE_LENGTH equ SAMPLE_END - SAMPLE_START
DISPLAY "Sample END :",/A,SAMPLE_END
DISPLAY "Sample START:",/A,SAMPLE_START
DISPLAY "# Samples :",/A,SAMPLE_LENGTH
IF (SAMPLE_LENGTH <= #6000)
DS (#6000 - SAMPLE_LENGTH)
ELSE
IF (SAMPLE_LENGTH <= #E000)
DS (#E000 - SAMPLE_LENGTH)
ELSE
IF (SAMPLE_LENGTH <= #1E000)
DS (#1E000 - SAMPLE_LENGTH)
ELSE
IF (SAMPLE_LENGTH <= #3E000)
DS (#3E000 - SAMPLE_LENGTH)
ELSE
IF (SAMPLE_LENGTH <= #7E000)
DS (#7E000 - SAMPLE_LENGTH)
ELSE
DS (#FE000 - SAMPLE_LENGTH)
ENDIF
ENDIF
ENDIF
ENDIF
ENDIF
FINISH:
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ARTRAG
msx master
Berichten: 1737 | Geplaatst: 21 Oktober 2007, 23:59 |
Rereading my old posts I've found an error
Quote:
| Great!
Can you post also the asm of a working program?
I've the feeling that bluemsx does not emulate correctly this behaviours,
your code, tested on the real HW, could be used to spot problems in the
emulators.
Anyway, the fact that channels at 1920Hz can have offsets is a very good
news!!
Can I guess a way to work with them?
0a) compute the phases as you proposed in you previous posts
(ch1 == original signal subsampled by 4 on phase 1)
(ch2 == original signal subsampled by 4 on phase 2 - ch1)
(ch3 == original signal subsampled by 4 on phase 3 - ch2)
(ch4 == original signal subsampled by 4 on phase 4 - ch3)
0b) reset the volumes of the 4 channels
loop :
1) reset volumes of ch2,ch3,ch4 => prevent errors in the first 4 samples of each loop
2a) fill ch1
2b) set freq and volume in ch1 => sample 1 is well reproduced as only ch1 is active
2c) wait 1/7680 secs
3a) fill ch2
3b) set freq and volume in ch2 => sample 2 should be well reproduced as only ch1&2 are active
3c) wait 1/7680 secs
4a) fill ch3
4b) set freq and volume in ch3 => sample 3 should be well reproduced as only ch1,2&3 are active
4c) wait 1/7680 secs
5a) fill ch4
5b) set freq and volume in ch4 => sample 4 should be well reproduced as all chs are active
5c) wait 1/7680 secs
6) wait (32/1920-4/7680) secs (the complement to, in order to keep cycle accuracy)
8) goto 1
If it works standalone as cycle accurate loop, it can go in an interrupt too.
and in any cases steps from 1) to 5b) must be cycle accurate even when in interrupts
If it works, the time "wasted" in the int routine is 3/7680 secs, not a lot, without considering that in each pause of 1/7680 secs you can do VDP I/O
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I was wrong in describing how to process input in order to get the channels:
The correct equations are:
ch1(1) = ph1(1);
ch2(1) = ph2(1) - ch1(1);
ch3(1) = ph3(1) - ch1(1) - ch2(1);
ch4(1) = ph4(1) - ch1(1) - ch2(1) - ch3(1);
for i=2:size(Y)/4
ch1(i) = ph1(i)-ch2(i-1)-ch3(i-1)-ch4(i-1);
ch2(i) = ph2(i)-ch1(i)-ch3(i-1)-ch4(i-1);
ch3(i) = ph3(i)-ch1(i)-ch2(i)-ch4(i-1);
ch4(i) = ph4(i)-ch1(i)-ch2(i)-ch3(i);
end
where Y is the input, phX is the input subsampled
on phase X and chX is channel X
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nikodr
msx addict
Berichten: 491 | Geplaatst: 22 Oktober 2007, 00:13 |
artrag i am now uploading the rom file to the megaflash
will post you in a few minutes and tell you what is happening  |
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nikodr
msx addict
Berichten: 491 | Geplaatst: 22 Oktober 2007, 00:25 |
It does not work for me,only strange colors appearing on screen and low noise is heard.I didn't hear any sound that i could understand...only some kind of noise,also the colors and shapes of colors were different from the ones bluemsx as a msx2 with konami scc mapper configuration appears on screen.
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dvik
msx master
Berichten: 1339 | Geplaatst: 22 Oktober 2007, 04:34 |
After updating blueMSX to what NYYRIKKI said about the channels, the program still doesn't work. I read the source and these forum post and I can't at all understand how its intended to work. Why do you set the period of CH4 to 32x CH1 +31 ? And how do you know what samples are being played based on the values in CH4. Did someone test it on a real cart?
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ARTRAG
msx master
Berichten: 1737 | Geplaatst: 22 Oktober 2007, 07:17 |
Well the idea was this:
The deformed channel rotate 32 times faster than its frequency.
If you set ch4 frequency at the vale you said, you should have that
the Freq of ch1 should be equal to the rotation frequency of ch4.
In this way for each sample played we get a step in the counter (ch4)
when ch4 passes from 0, we played 32 samples, so we can update ch1
wavetable
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dvik
msx master
Berichten: 1339 | Geplaatst: 22 Oktober 2007, 08:23 |
Yeah, I understand the part where the wrap of CH4 drives updating of the samples in CH1 but not the math and how the channels are synchronized.
I'm working on modifying the app a little bit as well as updating the emulator and if I get something that I think may work I'll post it here.
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dvik
msx master
Berichten: 1339 | Geplaatst: 22 Oktober 2007, 09:08 |
Some good progress, recorded in blueMSX: http://www.bluemsx.com/demos/sccplay_01.wav
I had to do both some hacking in the emulator and in ARTRAG's player. I'll clean up the player tomorrow night and post it here. Now its very hacky. If it works on a real MSX I think we've achieved something very amazing 
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ARTRAG
msx master
Berichten: 1737 | Geplaatst: 22 Oktober 2007, 09:58 |
My code is a blind experiment so it is by sure buggy 
dvik, what was wrong in it ?
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ARTRAG
msx master
Berichten: 1737 | Geplaatst: 22 Oktober 2007, 10:53 |
Ok, with the correction I did, all the volumes settings in the loop are unnecessary
I think that everything could be restated in this way:
ch1(1) = ph1(1);
ch2(1) = ph2(1) - ch1(1);
ch3(1) = ph3(1) - ch1(1) - ch2(1);
ch4(1) = ph4(1) - ch1(1) - ch2(1) - ch3(1);
for i=2:size(Y)/4
ch1(i) = ph1(i)-ch2(i-1)-ch3(i-1)-ch4(i-1);
ch2(i) = ph2(i)-ch1(i)-ch3(i-1)-ch4(i-1);
ch3(i) = ph3(i)-ch1(i)-ch2(i)-ch4(i-1);
ch4(i) = ph4(i)-ch1(i)-ch2(i)-ch3(i);
end
where Y is the input, phX is the input subsampled
on phase X and chX is channel X
1) set to zero the wave tables of the 4 channels
loop :
2a) load 32 bytes in ch1
2b) set freq in ch1 => sample 1 is well reproduced as only ch1 is active - in the first iteration -
2c) wait 1/7680 secs (the complement to, in order to keep timing accuracy)
3a) load 32 bytes in ch2
3b) set freq in ch2 => sample 2 should be well reproduced as only ch1&2 are active - in the first iteration -
3c) wait 1/7680 secs (the complement to, in order to keep timing accuracy)
4a) load 32 bytes in ch3
4b) set freq in ch3 => sample 3 should be well reproduced as only ch1,2&3 are active - in the first iteration -
4c) wait 1/7680 secs (the complement to, in order to keep timing accuracy)
5a) load 32 bytes in ch4
5b) set freq in ch4 => sample 4 should be well reproduced as all chs are active
5c) wait 1/7680 secs (the complement to, in order to keep cycle accuracy)
6) wait (32/1920-4/7680 = 124/7680) secs (the complement to, in order to keep cycle accuracy)
7) goto loop
According to the equations, original samples should be correctly reproduced even after the reproduction of first 4 samples,
and even between two loop iterations (i.e. the output of 32 samples).
Again, if it works standalone as cycle accurate loop, it can go in an interrupt too,
and in any case, steps from 2a) to 5b) must be cycle accurate even when in interrupts
If it works, the time "wasted" in the int routine is 3/7680 secs, not a lot, without considering that in each pause of 1/7680 secs you can do VDP I/O (you can fit about 25 outi in it)
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manuel
online
msx guru
Berichten: 3531 | Geplaatst: 22 Oktober 2007, 11:04 |
dvik, please share the ROM file, so we can test on real machines and on openMSX.
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nikodr
msx addict
Berichten: 491 | Geplaatst: 22 Oktober 2007, 12:15 |
I tested it on a real machine an msx2 philips NMS 8280 with a megaflash scc and only noice and some strange colors appeared.Can you send me the fixed rom dvik?
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NYYRIKKI
msx master
Berichten: 1525 | Geplaatst: 22 Oktober 2007, 15:15 |
Quote:
| I just checked: the info in NYYRIKKI's post seems to match the implementation in openMSX. Except for RR=11, in that case only channels 1-3 rotate and all channels are read-only.
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I think that I might be wrong here. The documentation that I wrote here does not match what I remember I wrote down to my self... I'll check my memos again when I'm at home...
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dvik
msx master
Berichten: 1339 | Geplaatst: 22 Oktober 2007, 16:22 |
I'll prepare the code and roms today. I worked quite late yesterday and had to go to sleep before I had something to share.
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nikodr
msx addict
Berichten: 491 | Geplaatst: 22 Oktober 2007, 16:25 |
Great dvik.I wait to see the roms and upload them on megaflash.Would rom be possible to be used on a memory mapped machine with a scc+ ?
I was thinking about a execrom patched rom to be used on machines with memory mapper and test this on Scc+ to see if it works too?i have an scc+ from snatcher.
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