80:
of the block (see below) which controls the size of steps between the 16 possible values such that minute changes can be recorded if the 16 values are closer together but minute changes are lost if the 16 values are far apart, two bits indicating the
274:
85:(see below), and two bits of control information for the SPC700. The remaining eight bytes consist of 16 signed 4-bit nibbles which correspond to the 16 samples, packed in a
560:
The PlayStation APU and the
Philips CD-i CDIC add another set of coefficients to the above and reorders them, for five unique of 8 filters total (these come from the
343:
310:
166:
539:
516:
493:
387:
363:
139:
119:
749:
675:
43:
557:. The denominators are powers of 2 to facilitate implementation with bit shifts as opposed to a more expensive hardware multiplier.
541:
bit downquantized version of the samples to the linear extrapolation from the last two samples (2nd order differential coding).
178:
549:
that is more resilient to errors in the encoded bitstream. Otherwise, any errors could propagate infinitely, as an
366:
561:
16:
This article is about the compression scheme used on the SPC-700. For other methods of bit-rate reduction, see
89:
manner. As 32 bytes of input become 9 bytes of output, the BRR algorithm yields a 3.56:1 compression ratio.
554:
744:
655:
465:
35:
518:
bit downquantized version of the samples to a lowered previous input (delta pack or differential coding).
69:
51:
545:
The coefficients of the above filters are specified as slightly less than 1 or 2 in order to realize a
76:. From most to least significant, the first byte of each block consists of four bits indicating the
687:
169:
315:
282:
550:
546:
58:
17:
144:
524:
501:
478:
372:
348:
345:
are the last-output and next-to-last-output PCM samples, respectively. The filter type
124:
104:
738:
47:
86:
55:
565:
39:
62:
73:
68:
BRR compresses each consecutive sequence of sixteen 16-bit
269:{\displaystyle s_{t}=2^{r}n+k_{1}s_{t-1}-k_{2}s_{t-2}}
527:
504:
481:
375:
351:
318:
285:
181:
147:
127:
107:
533:
510:
487:
381:
357:
337:
304:
268:
160:
133:
113:
654:These calculations are all done in signed 16.16
464:These calculations are all done in signed 16.16
8:
526:
503:
495:bit downquantized version of the samples.
480:
374:
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323:
317:
290:
284:
254:
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225:
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186:
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46:, as well as the audio processors of the
570:
391:
667:
7:
141:should be decoded into a PCM sample
750:Super Nintendo Entertainment System
14:
168:using the following second-order
61:series. The method is a form of
475:Filter 0 linearly decodes the
42:sound coprocessor used in the
1:
553:of an ideal integrator is a
389:using the following table:
766:
72:samples into a block of 9
15:
369:prediction coefficients
34:, is a name given to an
521:Filters 2 and 3 add an
338:{\displaystyle s_{t-2}}
305:{\displaystyle s_{t-1}}
101:in a block with filter
93:Decompression algorithm
656:fixed-point arithmetic
535:
512:
489:
466:fixed-point arithmetic
383:
359:
339:
306:
270:
162:
135:
115:
688:SPC 700 Documentation
536:
513:
490:
384:
360:
340:
307:
271:
163:
161:{\displaystyle s_{t}}
136:
116:
731:US Patent 5,978,492
728:US Patent 5,519,166
725:US Patent 5,430,241
722:US Patent 5,303,374
719:US Patent 5,166,981
716:US Patent 5,128,963
713:US Patent 5,111,530
710:US Patent 5,086,475
707:US Patent 5,070,515
704:US Patent 5,041,830
701:US Patent 4,829,522
698:US Patent 4,797,902
695:US Patent 4,783,792
692:US Patent 4,685,115
525:
502:
479:
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349:
316:
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179:
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105:
365:is translated into
38:method used on the
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379:
355:
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302:
266:
158:
131:
111:
24:Bit Rate Reduction
652:
651:
568:specifications):
534:{\displaystyle r}
511:{\displaystyle r}
498:Filter 1 adds an
488:{\displaystyle r}
462:
461:
382:{\displaystyle k}
358:{\displaystyle f}
170:linear prediction
134:{\displaystyle r}
114:{\displaystyle f}
36:audio compression
757:
680:
679:
672:
571:
551:impulse response
547:leaky integrator
540:
538:
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532:
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140:
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59:Macintosh Quadra
32:Bit Rate Reduced
18:data compression
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21:
12:
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5:
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94:
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30:, also called
13:
10:
9:
6:
4:
3:
2:
762:
751:
748:
746:
745:Digital audio
743:
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619:
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582:
579:
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569:
567:
563:
558:
556:
555:step function
552:
548:
528:
520:
505:
497:
482:
474:
473:
472:
471:Or in words:
469:
467:
457:
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153:
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128:
108:
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92:
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88:
84:
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66:
64:
60:
57:
53:
49:
45:
41:
37:
33:
29:
25:
19:
670:
653:
588:
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575:
559:
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470:
463:
409:
401:
396:
278:
98:
96:
82:
77:
67:
48:Philips CD-i
31:
27:
23:
22:
566:Yellow Book
52:PlayStation
739:Categories
662:References
562:Green Book
172:equation:
121:and range
87:big-endian
54:, and the
328:−
295:−
259:−
238:−
230:−
97:A nibble
676:"68kMLA"
574:Filter
395:Filter
648:15/16
637:55/64
626:13/16
623:115/64
458:13/16
455:115/64
447:15/16
279:Here,
83:filter
50:, the
40:SPC700
645:61/32
634:49/32
612:15/16
444:61/32
433:15/16
78:range
74:bytes
63:ADPCM
56:Apple
26:, or
564:and
312:and
44:SNES
367:IIR
70:PCM
28:BRR
741::
658:.
615:0
604:0
468:.
436:0
425:0
65:.
678:.
642:4
631:3
620:2
609:1
601:0
598:0
592:2
589:k
584:1
581:k
576:f
529:r
506:r
483:r
452:3
441:2
430:1
422:0
419:0
413:2
410:k
405:1
402:k
397:f
377:k
353:f
331:2
325:t
321:s
298:1
292:t
288:s
262:2
256:t
252:s
246:2
242:k
233:1
227:t
223:s
217:1
213:k
209:+
206:n
201:r
197:2
193:=
188:t
184:s
154:t
150:s
129:r
109:f
99:n
20:.
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