135:
33:
780:
705:
282:
The level (magnitude) of non-zero coefficients tends to be higher at the start of the reordered array (near the DC coefficient) and lower towards the higher frequencies. CAVLC takes advantage of this by adapting the choice of VLC look-up table for the “level” parameter depending on recently coded
265:(CABAC). CAVLC requires considerably less processing to decode than CABAC, although it does not compress the data quite as effectively. CAVLC is supported in all H.264 profiles, unlike CABAC which is not supported in Baseline and Extended profiles.
278:
The number of non-zero coefficients in neighbouring blocks is correlated. The number of coefficients is encoded using a look-up table; the choice of look-up table depends on the number of non-zero coefficients in neighbouring
261:
technique, like almost all entropy-coders. In H.264/MPEG-4 AVC, it is used to encode residual, zig-zag order, blocks of transform coefficients. It is an alternative to context-based adaptive binary
729:
The decoder has inserted two zeros; however, TotalZeros is equal to 3 and so another 1 zero is inserted before the lowest coefficient, making the final output array: 0, 3, 0, 1, −1, −1, 0, 1
268:
CAVLC is used to encode residual, zig-zag ordered 4×4 (and 2×2) blocks of transform coefficients. CAVLC is designed to take advantage of several characteristics of quantized 4×4 blocks:
156:
50:
275:
The highest non-zero coefficients after zig-zag scan are often sequences of +/− 1. CAVLC signals the number of high-frequency +/−1 coefficients in a compact way.
207:
97:
179:
69:
821:
726:
Decoding: The output array is “built up” from the decoded values as shown below. Values added to the output array at each stage are underlined.
186:
76:
193:
83:
226:
175:
116:
65:
855:
160:
54:
814:
200:
145:
90:
850:
164:
149:
43:
840:
807:
765:
272:
After prediction, transformation and quantization, blocks are typically sparse (containing mostly zeros).
738:
748:
258:
241:
711:
0, 3, 0, 1, −1, −1, 0, 1, 0… TotalCoeffs = 5 (indexed from highest frequency to lowest frequency )
262:
791:
787:
743:
254:
717:
T1s = 3 (in fact there are 4 trailing ones but only 3 can be encoded as a “special case”)
701:
In all following examples, we assume that table Num-VLC0 is used to encode coeff_token.
250:
845:
834:
292:
Parameters that required to be encoded and transmitted include the following table:
134:
32:
779:
723:
The transmitted bitstream for this block is 000010001110010111101101.
317:
Indicates which blocks within a macroblock contain coded coefficients
17:
704:
341:
Transmitted as a difference (mvd) from predicted motion vector
128:
26:
703:
325:
Transmitted as a delta value from the previous value of QP
795:
57:. Unsourced material may be challenged and removed.
333:Identify reference frame(s) for inter prediction
766:Context adaptive variable length coding tutorial
815:
8:
309:Prediction method for each coded macroblock
349:Coefficient data for each 4×4 or 2×2 block
163:. Unsourced material may be challenged and
822:
808:
506:
359:
227:Learn how and when to remove this message
176:"Context-adaptive variable-length coding"
117:Learn how and when to remove this message
66:"Context-adaptive variable-length coding"
294:
7:
776:
774:
501:No code required; last coefficient.
322:Quantizer parameter reference frame
257:video encoding. It is an inherently
161:adding citations to reliable sources
55:adding citations to reliable sources
794:. You can help Knowledge (XXG) by
25:
778:
133:
31:
42:needs additional citations for
1:
872:
773:
498:ZerosLeft=1; run_before=1
487:ZerosLeft=2; run_before=1
476:ZerosLeft=2; run_before=0
465:ZerosLeft=2; run_before=0
454:ZerosLeft=3; run_before=1
856:Computer science stubs
739:H.264 (entropy coding)
708:
530:Total Coeffs=5, T1s=3
330:Reference frame index
242:variable-length coding
707:
377:TotalCoeffs=5, T1s=3
749:Lossless compression
432:+3 (use Level_VLC1)
421:+1 (use Level_VLC0)
314:Coded block pattern
259:lossless compression
157:improve this article
51:improve this article
677:3, 1, −1, −1, 0, 1
663:3, 1, −1, −1, 0, 1
709:
695:, 1, −1, −1, 0, 1
851:Video compression
803:
802:
699:
698:
505:
504:
353:
352:
283:level magnitudes.
263:arithmetic coding
240:Context-adaptive
237:
236:
229:
211:
127:
126:
119:
101:
16:(Redirected from
863:
824:
817:
810:
788:computer science
782:
775:
744:Data compression
631:3, 1, −1, −1, 1
507:
360:
306:Macroblock type
295:
255:H.264/MPEG-4 AVC
232:
225:
221:
218:
212:
210:
169:
137:
129:
122:
115:
111:
108:
102:
100:
59:
35:
27:
21:
871:
870:
866:
865:
864:
862:
861:
860:
831:
830:
829:
828:
771:
762:
757:
735:
714:TotalZeros = 3
617:, 1, −1, −1, 1
358:
290:
249:) is a form of
233:
222:
216:
213:
170:
168:
154:
138:
123:
112:
106:
103:
60:
58:
48:
36:
23:
22:
15:
12:
11:
5:
869:
867:
859:
858:
853:
848:
843:
841:Entropy coding
833:
832:
827:
826:
819:
812:
804:
801:
800:
783:
769:
768:
761:
760:External links
758:
756:
753:
752:
751:
746:
741:
734:
731:
697:
696:
689:
686:
683:
679:
678:
675:
672:
669:
665:
664:
661:
658:
655:
651:
650:
645:3, 1, −1, −1,
643:
640:
637:
633:
632:
629:
626:
623:
619:
618:
612:
609:
606:
602:
601:
595:
592:
589:
585:
584:
578:
575:
572:
568:
567:
561:
558:
555:
551:
550:
545:
542:
539:
535:
534:
531:
528:
525:
521:
520:
517:
514:
511:
503:
502:
499:
496:
495:run_before(0)
492:
491:
488:
485:
484:run_before(1)
481:
480:
477:
474:
473:run_before(2)
470:
469:
466:
463:
462:run_before(3)
459:
458:
455:
452:
451:run_before(4)
448:
447:
444:
441:
437:
436:
433:
430:
426:
425:
422:
419:
415:
414:
411:
408:
404:
403:
400:
397:
393:
392:
389:
386:
382:
381:
378:
375:
371:
370:
367:
364:
357:
356:CAVLC examples
354:
351:
350:
347:
346:Residual data
343:
342:
339:
338:Motion vector
335:
334:
331:
327:
326:
323:
319:
318:
315:
311:
310:
307:
303:
302:
299:
289:
288:Coded elements
286:
285:
284:
280:
276:
273:
251:entropy coding
235:
234:
141:
139:
132:
125:
124:
39:
37:
30:
24:
14:
13:
10:
9:
6:
4:
3:
2:
868:
857:
854:
852:
849:
847:
844:
842:
839:
838:
836:
825:
820:
818:
813:
811:
806:
805:
799:
797:
793:
790:article is a
789:
784:
781:
777:
772:
767:
764:
763:
759:
754:
750:
747:
745:
742:
740:
737:
736:
732:
730:
727:
724:
721:
718:
715:
712:
706:
702:
694:
690:
687:
684:
681:
680:
676:
673:
670:
667:
666:
662:
659:
656:
653:
652:
648:
644:
641:
638:
635:
634:
630:
627:
624:
621:
620:
616:
613:
610:
607:
604:
603:
599:
596:
593:
590:
587:
586:
582:
579:
576:
573:
570:
569:
565:
562:
559:
556:
553:
552:
549:
546:
543:
540:
537:
536:
532:
529:
526:
523:
522:
519:Output array
518:
515:
512:
509:
508:
500:
497:
494:
493:
489:
486:
483:
482:
478:
475:
472:
471:
467:
464:
461:
460:
456:
453:
450:
449:
445:
442:
439:
438:
434:
431:
428:
427:
423:
420:
417:
416:
412:
409:
406:
405:
401:
398:
395:
394:
390:
387:
384:
383:
379:
376:
373:
372:
368:
365:
362:
361:
355:
348:
345:
344:
340:
337:
336:
332:
329:
328:
324:
321:
320:
316:
313:
312:
308:
305:
304:
300:
297:
296:
293:
287:
281:
277:
274:
271:
270:
269:
266:
264:
260:
256:
252:
248:
244:
243:
231:
228:
220:
209:
206:
202:
199:
195:
192:
188:
185:
181:
178: –
177:
173:
172:Find sources:
166:
162:
158:
152:
151:
147:
142:This article
140:
136:
131:
130:
121:
118:
110:
107:December 2022
99:
96:
92:
89:
85:
82:
78:
75:
71:
68: –
67:
63:
62:Find sources:
56:
52:
46:
45:
40:This article
38:
34:
29:
28:
19:
796:expanding it
785:
770:
728:
725:
722:
719:
716:
713:
710:
700:
692:
646:
614:
600:, −1, −1, 1
597:
580:
563:
547:
527:coeff_token
407:T1 sign (2)
396:T1 sign (3)
385:T1 sign (4)
374:coeff_token
301:Description
291:
267:
246:
239:
238:
223:
214:
204:
197:
190:
183:
171:
155:Please help
143:
113:
104:
94:
87:
80:
73:
61:
49:Please help
44:verification
41:
685:run_before
671:run_before
657:run_before
639:run_before
625:TotalZeros
440:TotalZeros
298:Parameters
835:Categories
755:References
720:Encoding:
429:Level (0)
418:Level (1)
217:April 2024
187:newspapers
77:newspapers
144:does not
733:See also
583:, −1, 1
574:T1 sign
557:T1 sign
541:T1 sign
524:0000100
513:Element
380:0000100
363:Element
253:used in
279:blocks.
201:scholar
165:removed
150:sources
91:scholar
608:Level
591:Level
533:Empty
516:Value
366:Value
203:
196:
189:
182:
174:
93:
86:
79:
72:
64:
786:This
605:0010
510:Code
435:0010
369:Code
247:CAVLC
208:JSTOR
194:books
98:JSTOR
84:books
18:CAVLC
846:MPEG
792:stub
649:, 1
622:111
566:, 1
446:111
180:news
148:any
146:cite
70:news
691:3,
682:01
636:10
611:+3
594:+1
490:01
457:10
159:by
53:by
837::
688:1
674:0
668:1
660:0
654:1
642:1
628:3
588:1
581:−1
577:-
571:1
564:−1
560:-
554:1
544:+
538:0
479:1
468:1
443:3
424:1
413:1
410:-
402:1
399:-
391:0
388:+
823:e
816:t
809:v
798:.
693:0
647:0
615:3
598:1
548:1
245:(
230:)
224:(
219:)
215:(
205:·
198:·
191:·
184:·
167:.
153:.
120:)
114:(
109:)
105:(
95:·
88:·
81:·
74:·
47:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
