H.264 CABAC values for 4:4:4

When a High 4:4:4 stream codes the Cb and Cr planes like luma (separate_colour_plane_flag 0, ChromaArrayType 3), their residual blocks use their own CABAC contexts, ctxIdx 460 to 1011; ctxIdx 1012 to 1023 are the coded_block_flag contexts of 8 × 8 blocks of all three components. This page lists their (m, n) pairs; ctxIdx 0 to 459 and the formula that turns a pair into a context state are on the CABAC initial values page. Source: ITU-T H.264 (06/2026, version 16), Tables 9-25 to 9-33, 9-34 and 9-40.

The spec prints the Cb and Cr contexts side by side with the same values, so each row below gives a Cb ctxIdx and the Cr ctxIdx that shares its values. Every set also repeats the values of the matching luma contexts, named in each section. Block categories (ctxBlockCat, Table 9-42): 6, 7, 8 are Cb DC, AC and 4 × 4 blocks and 10, 11, 12 the same for Cr, coded like luma categories 0, 1, 2; 9 and 13 are Cb and Cr 8 × 8 blocks, like luma category 5.

Context offsets

Table 9-34 gives the first ctxIdx of each element; Table 9-40 then adds a block category offset.

Syntax element	Cb (6 to 8)	Cr (10 to 12)	Cb 8 × 8 (9)	Cr 8 × 8 (13)
`coded_block_flag`	460	472	1012	1012
`significant_coeff_flag`, frame	484	528	660	718
`significant_coeff_flag`, field	776	820	675	733
`last_significant_coeff_flag`, frame	572	616	690	748
`last_significant_coeff_flag`, field	864	908	699	757
`coeff_abs_level_minus1`	952	982	708	766

ctxBlockCat	1	2	3	4	7	8	9	11	12	13
`coded_block_flag`	4	8	12	16	4	8	4	4	8	8
significant, last	15	29	44	47	15	29	0	15	29	0
`coeff_abs_level_minus1`	10	20	30	39	10	20	0	10	20	0

So coded_block_flag uses 1012 to 1015 for luma 8 × 8 blocks, 1016 to 1019 for Cb and 1020 to 1023 for Cr.

coded_block_flag

Cb 460 to 471 and Cr 472 to 483 (Table 9-25) repeat luma ctxIdx 85 to 96.

Cb	Cr	I and SI		cabac_init_idc 0		1		2
Cb	Cr	m	n	m	n	m	n	m	n
460	472	−17	123	−7	92	0	80	11	80
461	473	−12	115	−5	89	−5	89	5	76
462	474	−16	122	−7	96	−7	94	2	84
463	475	−11	115	−13	108	−4	92	5	78
464	476	−12	63	−3	46	0	39	−6	55
465	477	−2	68	−1	65	0	65	4	61
466	478	−15	84	−1	57	−15	84	−14	83
467	479	−13	104	−9	93	−35	127	−37	127
468	480	−3	70	−3	74	−2	73	−5	79
469	481	−8	93	−9	92	−12	104	−11	104
470	482	−10	90	−8	87	−9	91	−11	91
471	483	−30	127	−23	126	−31	127	−30	127

8 × 8 blocks, ctxIdx 1012 to 1023 (Table 9-33): each group of four repeats ctxIdx 93 to 96.

ctxIdx	I and SI		cabac_init_idc 0		1		2
ctxIdx	m	n	m	n	m	n	m	n
1012, 1016, 1020	−3	70	−3	74	−2	73	−5	79
1013, 1017, 1021	−8	93	−9	92	−12	104	−11	104
1014, 1018, 1022	−10	90	−8	87	−9	91	−11	91
1015, 1019, 1023	−30	127	−23	126	−31	127	−30	127

significant_coeff_flag, frame coded

Cb 484 to 527 and Cr 528 to 571 (Table 9-26) repeat luma ctxIdx 105 to 148. (The 2026 text prints ctxIdx 541 as “641”, between 540 and 542.)

Cb	Cr	I and SI		cabac_init_idc 0		1		2
Cb	Cr	m	n	m	n	m	n	m	n
484	528	−7	93	−2	85	−13	103	−4	86
485	529	−11	87	−6	78	−13	91	−12	88
486	530	−3	77	−1	75	−9	89	−5	82
487	531	−5	71	−7	77	−14	92	−3	72
488	532	−4	63	2	54	−8	76	−4	67
489	533	−4	68	5	50	−12	87	−8	72
490	534	−12	84	−3	68	−23	110	−16	89
491	535	−7	62	1	50	−24	105	−9	69
492	536	−7	65	6	42	−10	78	−1	59
493	537	8	61	−4	81	−20	112	5	66
494	538	5	56	1	63	−17	99	4	57
495	539	−2	66	−4	70	−78	127	−4	71
496	540	1	64	0	67	−70	127	−2	71
497	541	0	61	2	57	−50	127	2	58
498	542	−2	78	−2	76	−46	127	−1	74
499	543	1	50	11	35	−4	66	−4	44
500	544	7	52	4	64	−5	78	−1	69
501	545	10	35	1	61	−4	71	0	62
502	546	0	44	11	35	−8	72	−7	51
503	547	11	38	18	25	2	59	−4	47
504	548	1	45	12	24	−1	55	−6	42
505	549	0	46	13	29	−7	70	−3	41
506	550	5	44	13	36	−6	75	−6	53
507	551	31	17	−10	93	−8	89	8	76
508	552	1	51	−7	73	−34	119	−9	78
509	553	7	50	−2	73	−3	75	−11	83
510	554	28	19	13	46	32	20	9	52
511	555	16	33	9	49	30	22	0	67
512	556	14	62	−7	100	−44	127	−5	90
513	557	−13	108	9	53	0	54	1	67
514	558	−15	100	2	53	−5	61	−15	72
515	559	−13	101	5	53	0	58	−5	75
516	560	−13	91	−2	61	−1	60	−8	80
517	561	−12	94	0	56	−3	61	−21	83
518	562	−10	88	0	56	−8	67	−21	64
519	563	−16	84	−13	63	−25	84	−13	31
520	564	−10	86	−5	60	−14	74	−25	64
521	565	−7	83	−1	62	−5	65	−29	94
522	566	−13	87	4	57	5	52	9	75
523	567	−19	94	−6	69	2	57	17	63
524	568	1	70	4	57	0	61	−8	74
525	569	0	72	14	39	−9	69	−5	35
526	570	−5	74	4	51	−11	70	−2	27
527	571	18	59	13	68	18	55	13	91

last_significant_coeff_flag, frame coded

Cb 572 to 615 and Cr 616 to 659 (Table 9-27) repeat luma ctxIdx 166 to 209.

Cb	Cr	I and SI		cabac_init_idc 0		1		2
Cb	Cr	m	n	m	n	m	n	m	n
572	616	24	0	11	28	4	45	4	39
573	617	15	9	2	40	10	28	0	42
574	618	8	25	3	44	10	31	7	34
575	619	13	18	0	49	33	−11	11	29
576	620	15	9	0	46	52	−43	8	31
577	621	13	19	2	44	18	15	6	37
578	622	10	37	2	51	28	0	7	42
579	623	12	18	0	47	35	−22	3	40
580	624	6	29	4	39	38	−25	8	33
581	625	20	33	2	62	34	0	13	43
582	626	15	30	6	46	39	−18	13	36
583	627	4	45	0	54	32	−12	4	47
584	628	1	58	3	54	102	−94	3	55
585	629	0	62	2	58	0	0	2	58
586	630	7	61	4	63	56	−15	6	60
587	631	12	38	6	51	33	−4	8	44
588	632	11	45	6	57	29	10	11	44
589	633	15	39	7	53	37	−5	14	42
590	634	11	42	6	52	51	−29	7	48
591	635	13	44	6	55	39	−9	4	56
592	636	16	45	11	45	52	−34	4	52
593	637	12	41	14	36	69	−58	13	37
594	638	10	49	8	53	67	−63	9	49
595	639	30	34	−1	82	44	−5	19	58
596	640	18	42	7	55	32	7	10	48
597	641	10	55	−3	78	55	−29	12	45
598	642	17	51	15	46	32	1	0	69
599	643	17	46	22	31	0	0	20	33
600	644	0	89	−1	84	27	36	8	63
601	645	26	−19	25	7	33	−25	35	−18
602	646	22	−17	30	−7	34	−30	33	−25
603	647	26	−17	28	3	36	−28	28	−3
604	648	30	−25	28	4	38	−28	24	10
605	649	28	−20	32	0	38	−27	27	0
606	650	33	−23	34	−1	34	−18	34	−14
607	651	37	−27	30	6	35	−16	52	−44
608	652	33	−23	30	6	34	−14	39	−24
609	653	40	−28	32	9	32	−8	19	17
610	654	38	−17	31	19	37	−6	31	25
611	655	33	−11	26	27	35	0	36	29
612	656	40	−15	26	30	30	10	24	33
613	657	41	−6	37	20	28	18	34	15
614	658	38	1	28	34	26	25	30	20
615	659	41	17	17	70	29	41	22	73

8 × 8 Cb and Cr blocks

Cb (ctxBlockCat 9) 660 to 717 (Table 9-28) and Cr (13) 718 to 775 (Table 9-29) repeat the luma 8 × 8 contexts: significant frame 660/718 to 674/732 (as 402 to 416), significant field 675/733 to 689/747 (as 436 to 450), last frame 690/748 to 698/756 (as 417 to 425), last field 699/757 to 707/765 (as 451 to 459), level 708/766 to 717/775 (as 426 to 435). An I column is used because SI slices have no 8 × 8 transform.

Cb	Cr	I		cabac_init_idc 0		1		2
Cb	Cr	m	n	m	n	m	n	m	n
660	718	−17	120	−4	79	−5	85	−3	78
661	719	−20	112	−7	71	−6	81	−8	74
662	720	−18	114	−5	69	−10	77	−9	72
663	721	−11	85	−9	70	−7	81	−10	72
664	722	−15	92	−8	66	−17	80	−18	75
665	723	−14	89	−10	68	−18	73	−12	71
666	724	−26	71	−19	73	−4	74	−11	63
667	725	−15	81	−12	69	−10	83	−5	70
668	726	−14	80	−16	70	−9	71	−17	75
669	727	0	68	−15	67	−9	67	−14	72
670	728	−14	70	−20	62	−1	61	−16	67
671	729	−24	56	−19	70	−8	66	−8	53
672	730	−23	68	−16	66	−14	66	−14	59
673	731	−24	50	−22	65	0	59	−9	52
674	732	−11	74	−20	63	2	59	−11	68
675	733	−14	106	−5	85	−3	81	−3	78
676	734	−13	97	−6	81	−3	76	−8	74
677	735	−15	90	−10	77	−7	72	−9	72
678	736	−12	90	−7	81	−6	78	−10	72
679	737	−18	88	−17	80	−12	72	−18	75
680	738	−10	73	−18	73	−14	68	−12	71
681	739	−9	79	−4	74	−3	70	−11	63
682	740	−14	86	−10	83	−6	76	−5	70
683	741	−10	73	−9	71	−5	66	−17	75
684	742	−10	70	−9	67	−5	62	−14	72
685	743	−10	69	−1	61	0	57	−16	67
686	744	−5	66	−8	66	−4	61	−8	53
687	745	−9	64	−14	66	−9	60	−14	59
688	746	−5	58	0	59	1	54	−9	52
689	747	2	59	2	59	2	58	−11	68
690	748	23	−13	9	−2	17	−10	9	−2
691	749	26	−13	26	−9	32	−13	30	−10
692	750	40	−15	33	−9	42	−9	31	−4
693	751	49	−14	39	−7	49	−5	33	−1
694	752	44	3	41	−2	53	0	33	7
695	753	45	6	45	3	64	3	31	12
696	754	44	34	49	9	68	10	37	23
697	755	33	54	45	27	66	27	31	38
698	756	19	82	36	59	47	57	20	64
699	757	21	−10	21	−13	17	−10	9	−2
700	758	24	−11	33	−14	32	−13	30	−10
701	759	28	−8	39	−7	42	−9	31	−4
702	760	28	−1	46	−2	49	−5	33	−1
703	761	29	3	51	2	53	0	33	7
704	762	29	9	60	6	64	3	31	12
705	763	35	20	61	17	68	10	37	23
706	764	29	36	55	34	66	27	31	38
707	765	14	67	42	62	47	57	20	64
708	766	−3	75	−6	66	−5	71	−9	71
709	767	−1	23	−7	35	0	24	−7	37
710	768	1	34	−7	42	−1	36	−8	44
711	769	1	43	−8	45	−2	42	−11	49
712	770	0	54	−5	48	−2	52	−10	56
713	771	−2	55	−12	56	−9	57	−12	59
714	772	0	61	−6	60	−6	63	−8	63
715	773	1	64	−5	62	−4	65	−9	67
716	774	0	68	−8	66	−4	67	−6	68
717	775	−9	92	−8	76	−7	82	−10	79

significant_coeff_flag, field coded

Cb 776 to 819 and Cr 820 to 863 (Table 9-30) repeat luma ctxIdx 277 to 320.

Cb	Cr	I and SI		cabac_init_idc 0		1		2
Cb	Cr	m	n	m	n	m	n	m	n
776	820	−6	93	−13	106	−21	126	−22	127
777	821	−6	84	−16	106	−23	124	−25	127
778	822	−8	79	−10	87	−20	110	−25	120
779	823	0	66	−21	114	−26	126	−27	127
780	824	−1	71	−18	110	−25	124	−19	114
781	825	0	62	−14	98	−17	105	−23	117
782	826	−2	60	−22	110	−27	121	−25	118
783	827	−2	59	−21	106	−27	117	−26	117
784	828	−5	75	−18	103	−17	102	−24	113
785	829	−3	62	−21	107	−26	117	−28	118
786	830	−4	58	−23	108	−27	116	−31	120
787	831	−9	66	−26	112	−33	122	−37	124
788	832	−1	79	−10	96	−10	95	−10	94
789	833	0	71	−12	95	−14	100	−15	102
790	834	3	68	−5	91	−8	95	−10	99
791	835	10	44	−9	93	−17	111	−13	106
792	836	−7	62	−22	94	−28	114	−50	127
793	837	15	36	−5	86	−6	89	−5	92
794	838	14	40	9	67	−2	80	17	57
795	839	16	27	−4	80	−4	82	−5	86
796	840	12	29	−10	85	−9	85	−13	94
797	841	1	44	−1	70	−8	81	−12	91
798	842	20	36	7	60	−1	72	−2	77
799	843	18	32	9	58	5	64	0	71
800	844	5	42	5	61	1	67	−1	73
801	845	1	48	12	50	9	56	4	64
802	846	10	62	15	50	0	69	−7	81
803	847	17	46	18	49	1	69	5	64
804	848	9	64	17	54	7	69	15	57
805	849	−12	104	10	41	−7	69	1	67
806	850	−11	97	7	46	−6	67	0	68
807	851	−16	96	−1	51	−16	77	−10	67
808	852	−7	88	7	49	−2	64	1	68
809	853	−8	85	8	52	2	61	0	77
810	854	−7	85	9	41	−6	67	2	64
811	855	−9	85	6	47	−3	64	0	68
812	856	−13	88	2	55	2	57	−5	78
813	857	4	66	13	41	−3	65	7	55
814	858	−3	77	10	44	−3	66	5	59
815	859	−3	76	6	50	0	62	2	65
816	860	−6	76	5	53	9	51	14	54
817	861	10	58	13	49	−1	66	15	44
818	862	−1	76	4	63	−2	71	5	60
819	863	−1	83	6	64	−2	75	2	70

last_significant_coeff_flag, field coded

Cb 864 to 907 and Cr 908 to 951 (Table 9-31) repeat luma ctxIdx 338 to 381.

Cb	Cr	I and SI		cabac_init_idc 0		1		2
Cb	Cr	m	n	m	n	m	n	m	n
864	908	15	6	14	11	19	−6	17	−13
865	909	6	19	11	14	18	−6	16	−9
866	910	7	16	9	11	14	0	17	−12
867	911	12	14	18	11	26	−12	27	−21
868	912	18	13	21	9	31	−16	37	−30
869	913	13	11	23	−2	33	−25	41	−40
870	914	13	15	32	−15	33	−22	42	−41
871	915	15	16	32	−15	37	−28	48	−47
872	916	12	23	34	−21	39	−30	39	−32
873	917	13	23	39	−23	42	−30	46	−40
874	918	15	20	42	−33	47	−42	52	−51
875	919	14	26	41	−31	45	−36	46	−41
876	920	14	44	46	−28	49	−34	52	−39
877	921	17	40	38	−12	41	−17	43	−19
878	922	17	47	21	29	32	9	32	11
879	923	24	17	45	−24	69	−71	61	−55
880	924	21	21	53	−45	63	−63	56	−46
881	925	25	22	48	−26	66	−64	62	−50
882	926	31	27	65	−43	77	−74	81	−67
883	927	22	29	43	−19	54	−39	45	−20
884	928	19	35	39	−10	52	−35	35	−2
885	929	14	50	30	9	41	−10	28	15
886	930	10	57	18	26	36	0	34	1
887	931	7	63	20	27	40	−1	39	1
888	932	−2	77	0	57	30	14	30	17
889	933	−4	82	−14	82	28	26	20	38
890	934	−3	94	−5	75	23	37	18	45
891	935	9	69	−19	97	12	55	15	54
892	936	−12	109	−35	125	11	65	0	79
893	937	36	−35	27	0	37	−33	36	−16
894	938	36	−34	28	0	39	−36	37	−14
895	939	32	−26	31	−4	40	−37	37	−17
896	940	37	−30	27	6	38	−30	32	1
897	941	44	−32	34	8	46	−33	34	15
898	942	34	−18	30	10	42	−30	29	15
899	943	34	−15	24	22	40	−24	24	25
900	944	40	−15	33	19	49	−29	34	22
901	945	33	−7	22	32	38	−12	31	16
902	946	35	−5	26	31	40	−10	35	18
903	947	33	0	21	41	38	−3	31	28
904	948	38	2	26	44	46	−5	33	41
905	949	33	13	23	47	31	20	36	28
906	950	23	35	16	65	29	30	27	47
907	951	13	58	14	71	25	44	21	62

coeff_abs_level_minus1

Cb 952 to 981 and Cr 982 to 1011 (Table 9-32) repeat luma ctxIdx 227 to 256.

Cb	Cr	I and SI		cabac_init_idc 0		1		2
Cb	Cr	m	n	m	n	m	n	m	n
952	982	−3	71	−6	76	−23	112	−24	115
953	983	−6	42	−2	44	−15	71	−22	82
954	984	−5	50	0	45	−7	61	−9	62
955	985	−3	54	0	52	0	53	0	53
956	986	−2	62	−3	64	−5	66	0	59
957	987	0	58	−2	59	−11	77	−14	85
958	988	1	63	−4	70	−9	80	−13	89
959	989	−2	72	−4	75	−9	84	−13	94
960	990	−1	74	−8	82	−10	87	−11	92
961	991	−9	91	−17	102	−34	127	−29	127
962	992	−5	67	−9	77	−21	101	−21	100
963	993	−5	27	3	24	−3	39	−14	57
964	994	−3	39	0	42	−5	53	−12	67
965	995	−2	44	0	48	−7	61	−11	71
966	996	0	46	0	55	−11	75	−10	77
967	997	−16	64	−6	59	−15	77	−21	85
968	998	−8	68	−7	71	−17	91	−16	88
969	999	−10	78	−12	83	−25	107	−23	104
970	1000	−6	77	−11	87	−25	111	−15	98
971	1001	−10	86	−30	119	−28	122	−37	127
972	1002	−12	92	1	58	−11	76	−10	82
973	1003	−15	55	−3	29	−10	44	−8	48
974	1004	−10	60	−1	36	−10	52	−8	61
975	1005	−6	62	1	38	−10	57	−8	66
976	1006	−4	65	2	43	−9	58	−7	70
977	1007	−12	73	−6	55	−16	72	−14	75
978	1008	−8	76	0	58	−7	69	−10	79
979	1009	−7	80	0	64	−4	69	−9	83
980	1010	−9	88	−3	74	−5	74	−12	92
981	1011	−17	110	−10	90	−9	86	−18	108

.H264 File Format – CABAC values for 4:4:4