[PD-cvs] SF.net SVN: pure-data:[10470] trunk/pd/doc/3.audio.examples

[millerpuckette at users.sourceforge.net]

Revision: 10470
          http://pure-data.svn.sourceforge.net/pure-data/?rev=10470&view=rev
Author:   millerpuckette
Date:     2008-12-30 01:53:20 +0000 (Tue, 30 Dec 2008)

Log Message:
-----------
Oops, add 2 help files

Added Paths:
-----------
    trunk/pd/doc/3.audio.examples/B15.tabread4~-onset.pd
    trunk/pd/doc/3.audio.examples/B16.long-varispeed.pd

Added: trunk/pd/doc/3.audio.examples/B15.tabread4~-onset.pd
===================================================================
--- trunk/pd/doc/3.audio.examples/B15.tabread4~-onset.pd	                        (rev 0)
+++ trunk/pd/doc/3.audio.examples/B15.tabread4~-onset.pd	2008-12-30 01:53:20 UTC (rev 10470)
@@ -0,0 +1,66 @@
+#N canvas 88 58 563 680 12;
+#X text 355 655 updated for Pd version 0.42;
+#X text 28 36 Pd is usually compiled to work on 32-bit audio samples.
+These do not \, in general \, have enough precision for use as indices
+into an array of more than about 32K samples. This is because the mantissa
+of a 23-bit floating point number has only 24 bits \, out of which
+you would be using 16 bits or more to address a sample more than 32K
+into the array \, so there would remain 8 or fewer bits to supply the
+fraction. In the most extreme situation possible \, the sample could
+contain a Nyquist frequency sinusoid and the output would then have
+only about 8 bits of accuracy!;
+#X text 29 196 You can use the "onset" inlet to tabread4~ to get good
+accuracy reading longer arrays. The tabread4~ object adds the index
+and the "main" (signal) inlet in 64-bit precision. So if \, for example
+\, the onset inlet could specify an integer exactly up to about 8 million
+(190 seconds at 44100 Hz) \, and the signal inlet could act as a displacement.
+;
+#X text 116 13 USING ONSETS INTO TABREAD4~ TO IMPROVE ACCURACY;
+#X obj 41 587 output~;
+#X obj 395 507 samplerate~;
+#X obj 395 531 / 2;
+#X obj 384 445 loadbang;
+#X obj 384 582 tabwrite~ \$0-tab;
+#X obj 40 557 tabread4~ \$0-tab;
+#X obj 395 555 osc~;
+#X obj 172 557 tabread4~ \$0-tab;
+#X obj 173 589 output~;
+#X obj 384 486 bng 15 250 50 0 empty empty empty 17 7 0 10 -262144
+-1 -1;
+#X msg 408 468 \; pd dsp 1;
+#X obj 41 474 *~ 10000;
+#X obj 41 527 +~;
+#X floatatom 192 476 6 0 0 0 - - -;
+#X msg 247 446 1;
+#X obj 383 610 table \$0-tab 200000;
+#X obj 42 446 phasor~ 0.02;
+#X msg 192 446 150001;
+#X text 28 310 At left below an onset (1 or 150000 samples) is added
+to the index of a table lookup. If you select the onset of 150001 \,
+you should hear the truncation error. (The table contains a Nyquist
+signal and the "correct" output should be a 100 Hz. tone.) At right
+\, the onset is presented in the separate onset inlet. The worst-case
+truncation error drops by about 30 dB.;
+#X text 57 647 BAD;
+#X text 190 646 GOOD;
+#X text 193 425 ONSET INTO TABLE;
+#X text 384 426 This loads the table:;
+#X connect 5 0 6 0;
+#X connect 6 0 10 0;
+#X connect 7 0 13 0;
+#X connect 7 0 14 0;
+#X connect 9 0 4 0;
+#X connect 9 0 4 1;
+#X connect 10 0 8 0;
+#X connect 11 0 12 0;
+#X connect 11 0 12 1;
+#X connect 13 0 5 0;
+#X connect 13 0 8 0;
+#X connect 15 0 16 0;
+#X connect 15 0 11 0;
+#X connect 16 0 9 0;
+#X connect 17 0 11 1;
+#X connect 17 0 16 1;
+#X connect 18 0 17 0;
+#X connect 20 0 15 0;
+#X connect 21 0 17 0;

Added: trunk/pd/doc/3.audio.examples/B16.long-varispeed.pd
===================================================================
--- trunk/pd/doc/3.audio.examples/B16.long-varispeed.pd	                        (rev 0)
+++ trunk/pd/doc/3.audio.examples/B16.long-varispeed.pd	2008-12-30 01:53:20 UTC (rev 10470)
@@ -0,0 +1,158 @@
+#N canvas 31 5 779 858 12;
+#X obj 399 526 metro 100;
+#X obj 212 472 phasor~;
+#X obj 399 556 snapshot~;
+#X text 561 824 updated for Pd version 0.42;
+#X obj 23 557 output~;
+#X obj 23 461 phasor~;
+#X floatatom 23 329 5 -100 1000 0 - - -;
+#X obj 23 518 tabread4~ \$0-tab;
+#X msg 290 329 0.5;
+#X msg 326 329 0.01;
+#X obj 398 455 loadbang;
+#X msg 399 478 1;
+#X obj 344 635 +;
+#X obj 144 680 tabread4~ \$0-tab;
+#X obj 375 634 f;
+#X obj 312 612 t f f;
+#X obj 145 712 output~;
+#X floatatom 455 667 8 0 0 0 - - -;
+#X obj 344 670 t f b;
+#X obj 377 699 f;
+#X obj 344 699 -;
+#X floatatom 457 612 8 0 0 0 - - -;
+#X obj 326 726 -;
+#X obj 399 507 tgl 15 0 empty empty empty 17 7 0 10 -262144 -1 -1 1
+1;
+#X obj 212 498 -~ 0.5;
+#X obj 290 811 + 0.5;
+#X obj 22 490 *~ 1e+06;
+#X floatatom 326 753 8 0 0 0 - - -;
+#X obj 530 519 samplerate~;
+#X obj 484 546 /;
+#X obj 484 519 t f b;
+#X obj 451 589 +;
+#X obj 295 787 / 10000;
+#X obj 212 523 *~ 10000;
+#X obj 484 570 * 10000;
+#X obj 532 155 samplerate~;
+#X obj 532 179 / 2;
+#X obj 521 93 loadbang;
+#X obj 521 230 tabwrite~ \$0-tab;
+#X obj 532 203 osc~;
+#X obj 521 134 bng 15 250 50 0 empty empty empty 17 7 0 10 -262144
+-1 -1;
+#X msg 545 116 \; pd dsp 1;
+#X obj 520 258 table \$0-tab 1e+06;
+#X text 488 61 and will take about 20 seconds to fill.;
+#X text 488 45 *** The table is now 1 million points \,;
+#X obj 23 433 / 1e+06;
+#X text 61 328 playback speed \, samples/sec;
+#X text 89 460 naive way: just;
+#X text 89 475 run a phasor;
+#X text 88 491 into tabread4~;
+#X text 454 680 new onset is phase plus old onset;
+#X obj 341 357 * 1e+06;
+#X text 458 626 extrapolated phase of next sample;
+#X text 409 700 new onset minus old onset;
+#X text 389 726 back up phasor output by amount the onset advanced
+;
+#X text 387 739 (approximately zero but not exactly because of;
+#X text 389 753 truncation error!);
+#X obj 341 383 t b f;
+#X text 400 357 convert to samples;
+#X text 385 384 set both last-onset and previous-onset;
+#X text 385 407 ... and also reset phasor.;
+#X text 354 791 convert phase back to range 0-1;
+#X text 215 548 convert phase to;
+#X text 215 562 range +/-5000;
+#X obj 212 435 / 10000;
+#X text 40 410 cycles/sec;
+#X text 30 400 convert to;
+#X text 216 412 cycles/sec;
+#X text 206 402 convert to;
+#X text 469 472 in order to change onset to reflect it;
+#X text 469 456 Each 100 msec \, poll phase of phasor~;
+#X text 24 29 Here is how to use the tabread~ "onset" input to allow
+clean varispeed playback from a long table. At left \, a phasor~ is
+naiveley rescaled to the size of the tble. At right \, the phasor~
+gets only a 10000-point range about a moving "onset". Ten times per
+second \, we poll tha phasor~ phase \, sum its value into the onset
+\, and back up the phase of the phasor~ correspondingly.;
+#X text 24 138 The tricky bits are \, first \, that we need to poll
+the phasor~ phase one sample into the future (so we add the per-sample
+increment into the snapshot~ result). Second \, we can't just reset
+the phasor~ to a fixed point - instead \, we measure how much the onset
+has actually increased (which has truncation error from summing in
+the phase snapshot) \, and subtract that increase from the phase \,
+giving a value that differs from zero by the truncation error but reflects
+the true phase we should reset to for continuity.;
+#X text 26 281 The metronome rate is arbitrary but should be fast enough
+that the phasor~ never has time to wrap.;
+#X text 518 539 extrapolate snapshot of phase by one;
+#X text 517 552 sample to sync with next block;
+#X text 41 617 BAD;
+#X text 160 770 GOOD;
+#X text 195 9 VARIABLE SPEED PLAYBACK FROM LONG TABLES;
+#X msg 340 408 0;
+#X text 369 328 <- reset phase. 0.5 causes trouble for the "bad" way.
+;
+#X connect 0 0 2 0;
+#X connect 1 0 24 0;
+#X connect 2 0 31 0;
+#X connect 5 0 26 0;
+#X connect 6 0 45 0;
+#X connect 6 0 64 0;
+#X connect 7 0 4 0;
+#X connect 7 0 4 1;
+#X connect 8 0 5 1;
+#X connect 8 0 51 0;
+#X connect 9 0 5 1;
+#X connect 9 0 51 0;
+#X connect 10 0 11 0;
+#X connect 11 0 23 0;
+#X connect 12 0 14 0;
+#X connect 12 0 18 0;
+#X connect 12 0 13 1;
+#X connect 12 0 17 0;
+#X connect 13 0 16 0;
+#X connect 13 0 16 1;
+#X connect 14 0 12 1;
+#X connect 15 0 22 0;
+#X connect 15 1 12 0;
+#X connect 18 0 19 1;
+#X connect 18 0 20 0;
+#X connect 18 1 19 0;
+#X connect 19 0 20 1;
+#X connect 20 0 22 1;
+#X connect 22 0 27 0;
+#X connect 22 0 32 0;
+#X connect 23 0 0 0;
+#X connect 24 0 33 0;
+#X connect 25 0 1 1;
+#X connect 26 0 7 0;
+#X connect 28 0 29 1;
+#X connect 29 0 34 0;
+#X connect 30 0 29 0;
+#X connect 30 1 28 0;
+#X connect 31 0 15 0;
+#X connect 31 0 21 0;
+#X connect 32 0 25 0;
+#X connect 33 0 2 0;
+#X connect 33 0 13 0;
+#X connect 34 0 31 1;
+#X connect 35 0 36 0;
+#X connect 36 0 39 0;
+#X connect 37 0 40 0;
+#X connect 37 0 41 0;
+#X connect 39 0 38 0;
+#X connect 40 0 35 0;
+#X connect 40 0 38 0;
+#X connect 45 0 5 0;
+#X connect 51 0 57 0;
+#X connect 57 0 79 0;
+#X connect 57 1 19 1;
+#X connect 57 1 12 1;
+#X connect 64 0 1 0;
+#X connect 64 0 30 0;
+#X connect 79 0 15 0;


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