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Atari coding BBS
 
Re: Lance's 50 KHz playroutine
Posted by: ljbk Mar,08.2013-02:10 

Hi !

As anyone any information on the Octalyser UMP player format ?
What is the structure or format ?
How are parameters passed and returned ?
I looked inside the zip of Octalyser 0.96r but there is no help there.

Evil,

Regarding the 8 voices at 50 KHz here is the most plausible (guessed) way it works as there is no source.
The voices are all mixed 2 by 2 as with 4 voices mixed at once, the number of read speed combinations would be 23*23*23*23 = 279841 ... :D
One of the 4 mixed voices on the left and on the right still use the LCM for volume control.
The first mixed pair of voices is done like like in the basic 4 voices replay.
The worse case is (B-3 with FineTune) with 657 reads and 343 keep previous value:
657 reads maximum
move.b (a0),d0 08
move.b (a0),d1
move.l d1,a2
move.b (a2),d1 20
move.b d0,d2
add.b d1,d2 08
move.b d2,(sp)+ 08
--------------------------
44
343 times with no read
move.b d2,(sp)+ 08
--------------------------
08
So this uses a miximum of: 657 x 44 + 343 x 08 = 31652 cycles
The second pair of voices is done with 2 volumed samples like without the LCM trick and on top of that teh update buffer is done with a add and not a move:
657 reads maximum
move.b (a0),d0
move.l d0,a2
move.b (a2),d0 20
move.b (a0),d1
move.l d1,a2
move.b (a2),d1 20
move.b d0,d2
add.b d1,d2 08
add.b d2,(sp)+ 12
--------------------------
60
343 times with no read
add.b d2,(sp)+ 12
--------------------------
12
So this uses a miximum of: 657 x 60 + 343 x 12 = 43536 cycles
So we have 2 sets of 529 (23 x 23) generated routines: one with move and one with add. This would only work with 6 bit samples.
In total we have: 31652 + 43536 = 75188 cycles

To these cycles, you have to add the calling part cycles + the jmp for each of the 25 chunks + the mod handler but let's consider all this proporcional between the 2 cases as the mixed code usage is.

The used CPU can be estimated like this considering a 35% CPU usage with 4 voices:

(75188/31652) x 35% = 83% CPU ...

If we consider 100% CPU usage then the worst case mod at 4 voices would take:

100 % / (75188/31652) = 42.10% CPU

These values are in line with what Lance refers in the docs and show that most if not all 8 voices mods can be played at 50 KHz on STE following this strategy.

I will NOT do this. But anyone who has understood the "blog" previously exposed in Hacking Lance can follow this tip.
Please do not forget that the final quality will not be good has:
- 6 bit samples are used;
- LCM control is used for volume of 2 out of 8 voices (4.5 bit non linear for 6 bits linear);
- mixing of 4 voices into 1 for Left and Right speakers require amplification (VQ factor in Hextracker) otherwise the volume will be low because the mixing result will mostly be in a small part (middle) of the 8 bit DACs data space: most of the values will be distributed other the middle 7 bit values => lower quality than possible;


Have fun,
Paulo.





[All messages in this thread]    [Start new thread]

Topic Posted by  Date 
Lance's 50khz playroutine Bod/STAX Feb,18.2013-17:35
  Re: Lance's 50khz playroutine gwEm Feb,18.2013-20:42
  Re: Lance's 50khz playroutine ggn Feb,18.2013-20:53
    Re: Lance's 50khz playroutine Bod/STAX Feb,18.2013-21:28
      Re: Lance's 50khz playroutine gwEm Feb,18.2013-23:05
        Re: Lance's 50khz playroutine gwEm Feb,18.2013-23:16
          Re: Lance's 50khz playroutine gwEm Feb,19.2013-02:21
            Re: Lance's 50khz playroutine Bod/STAX Feb,22.2013-17:08
              Re: Lance's 50khz playroutine gwEm Feb,25.2013-20:36
                Re: Lance's 50khz playroutine ljbk Feb,25.2013-23:54
                  Re: Lance's 50khz playroutine Bod/STAX Feb,26.2013-11:23
                    Re: Lance's 50khz playroutine evil Feb,26.2013-12:04
                      Re: Lance's 50khz playroutine ljbk Feb,26.2013-14:45
                        Re: Lance's 50khz playroutine ljbk Feb,26.2013-21:46
                          Re: Lance's 50khz playroutine evil Feb,27.2013-17:01
                            Re: Lance's 50khz playroutine ljbk Feb,28.2013-13:24
                              Re: Lance's 50khz playroutine ljbk Feb,28.2013-13:28
                                Re: Lance's 50khz playroutine gwEm Feb,28.2013-14:07
                                  Re: Lance's 50khz playroutine Bod/STAX Feb,28.2013-21:41
                                    Re: Lance's 50khz playroutine ljbk Feb,28.2013-22:42
                                      Sem assunto ljbk Mar,01.2013-13:27
                                        Lance's 50 KHz playroutine ljbk Mar,01.2013-15:49
                                          Re: Lance's 50 KHz playroutine ljbk Mar,01.2013-17:34
                                            Re: Lance's 50 KHz playroutine ljbk Mar,01.2013-17:36
                                              Re: Lance's 50 KHz playroutine evil Mar,01.2013-19:03
                                                Re: Lance's 50 KHz playroutine ljbk Mar,02.2013-00:18
                                                  Re: Lance's 50 KHz playroutine ljbk Mar,04.2013-17:39
                                                    Re: Lance's 50 KHz playroutine ljbk Mar,06.2013-02:21
                                                      Re: Lance's 50 KHz playroutine gwEm Mar,06.2013-13:23
                                                        Re: Lance's 50 KHz playroutine ljbk Mar,06.2013-15:57
                                                          Re: Lance's 50 KHz playroutine evil Mar,06.2013-16:48
                                                            Re: Lance's 50 KHz playroutine ggn Mar,06.2013-17:31
                                                              Re: Lance's 50 KHz playroutine evil Mar,06.2013-17:48
                                                                Re: Lance's 50 KHz playroutine ggn Mar,06.2013-23:54
                                                            Re: Lance's 50 KHz playroutine ljbk Mar,06.2013-18:18
                                                              Re: Lance's 50 KHz playroutine ljbk Mar,06.2013-21:51
                                                              Re: Lance's 50 KHz playroutine ggn Mar,06.2013-23:59
                                                                Re: Lance's 50 KHz playroutine ljbk Mar,07.2013-02:31
                                                                  Re: Lance's 50 KHz playroutine ggn Mar,07.2013-12:34
                                                                    Re: Lance's 50 KHz playroutine ljbk Mar,07.2013-14:00
                                                                      Re: Lance's 50 KHz playroutine gwEm Mar,07.2013-18:00
                                                                        Re: Lance's 50 KHz playroutine ljbk Mar,07.2013-18:51
                                                                          Re: Lance's 50 KHz playroutine ljbk Mar,08.2013-02:10
                                                                            Re: Lance's 50 KHz playroutine ljbk Mar,08.2013-13:12
                                                                              Re: Lance's 50 KHz playroutine ljbk Mar,09.2013-00:17
                                                            Re: Lance's 50 KHz playroutine ljbk Mar,06.2013-19:28
                              Re: Lance's 50khz playroutine ljbk Feb,28.2013-15:47
                                Re: Lance's 50khz playroutine ljbk Feb,28.2013-15:51
                                  Re: Lance's 50khz playroutine ljbk Feb,28.2013-18:56
                                    Re: Lance's 50khz playroutine nativ Mar,24.2013-00:07
                                      Re: Lance's 50khz playroutine ljbk Apr,13.2013-01:21
                                        Re: Lance's 50khz playroutine ljbk Apr,16.2013-16:12
                                          Re: Lance's 50khz playroutine ljbk Apr,19.2013-12:14
                                            Re: Lance's 50khz playroutine ljbk Apr,22.2013-14:54
                                              Re: Lance's 50khz playroutine ljbk Apr,25.2013-19:03
                                                Re: Lance's 50khz playroutine ggn Apr,25.2013-21:03
                                                  Re: Lance's 50khz playroutine ljbk Apr,26.2013-09:18
                                                    Re: Lance's 50khz playroutine ggn Apr,26.2013-11:28
                                                      Re: Lance's 50khz playroutine ljbk Apr,26.2013-12:13
  Re: Lance's 50khz playroutine ljbk May,01.2013-22:30
    Re: Lance's 50khz playroutine evil May,02.2013-14:46
      Re: Lance's 50khz playroutine gwEm May,02.2013-20:00
        Re: Lance's 50khz playroutine Damo May,02.2013-21:00
          Re: Lance's 50khz playroutine evil May,03.2013-13:00
      Re: Lance's 50khz playroutine ljbk May,08.2013-17:50
        Re: Lance's 50khz playroutine Cyprian May,10.2013-13:01
          Re: Lance's 50khz playroutine ljbk May,11.2013-00:22
          Re: Lance's 50khz playroutine ljbk May,11.2013-08:54
            Re: Lance's 50khz playroutine Cyprian May,11.2013-15:18
              Re: Lance's 50khz playroutine ljbk May,11.2013-15:35
                Re: Lance's 50khz playroutine Lance May,23.2013-00:02
                  Re: Lance's 50khz playroutine ljbk May,23.2013-14:44
  Re: Lance's 50khz playroutine Bod/STAX Jun,06.2013-20:32
    Re: Lance's 50khz playroutine Bod/STAX Jun,06.2013-20:39
      Re: Lance's 50khz playroutine ljbk Jun,07.2013-00:09
        Re: Lance's 50khz playroutine Bod/STAX Jun,07.2013-18:38
          Re: Lance's 50khz playroutine ljbk Jun,07.2013-21:46


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