04 翻译任务.docx
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04翻译任务
9Parsingprocess
InputstothisprocessarebitsfromtheRBSP.
Outputsofthisprocessaresyntaxelementvalues.
Thisprocessisinvokedwhenthedescriptorofasyntaxelementinthesyntaxtablesinsubclause7.3isequalto ue（v）,me（v）,se（v）,te（v）（seesubclause9.1）,ce（v）（seesubclause9.2）,orae（v）（seesubclause9.3）.
9.1ParsingprocessforExp-Golombcodes
Thisprocessisinvokedwhenthedescriptorofasyntaxelementinthesyntaxtablesinsubclause7.3isequalto ue（v）,me（v）,se（v）,orte（v）.Forsyntaxelementsinsubclauses7.3.4and7.3.5,thisprocessisinvokedonlywhenentropy_coding_mode_flagisequalto 0.
InputstothisprocessarebitsfromtheRBSP.
Outputsofthisprocessaresyntaxelementvalues.
Syntaxelementscodedasue（v）,me（v）,orse（v）areExp-Golomb-coded.Syntaxelementscodedaste（v）aretruncatedExp-Golomb-coded.Theparsingprocessforthesesyntaxelementsbeginswithreadingthebitsstartingatthecurrentlocationinthebitstreamuptoandincludingthefirstnon-zerobit,andcountingthenumberofleadingbitsthatareequalto 0.Thisprocessshallbeequivalenttothefollowing:
leadingZeroBits=-1;
for（b=0;!
b;leadingZeroBits++）
b=read_bits
（1）
ThevariablecodeNumisthenassignedasfollows:
codeNum=2leadingZeroBits–1+read_bits（leadingZeroBits）
wherethevaluereturnedfromread_bits（leadingZeroBits）isinterpretedasabinaryrepresentationofanunsignedintegerwithmostsignificantbitwrittenfirst.
Table 91illustratesthestructureoftheExp-Golombcodebyseparatingthebitstringinto“prefix”and“suffix”bits.The“prefix”bitsarethosebitsthatareparsedintheabovepseudo-codeforthecomputationofleadingZeroBits,andareshownaseither0or1inthebitstringcolumnofTable 91.The“suffix”bitsarethosebitsthatareparsedinthecomputationofcodeNumandareshownasxiinTable 91,withibeingintherange0toleadingZeroBits - 1,inclusive.Eachxicantakeonvalues0or1.
Table 91–Bitstringswith“prefix”and“suffix”bitsandassignmenttocodeNumranges（informative）
Bitstringform
RangeofcodeNum
1
0
01x0
1-2
001x1x0
3-6
0001x2x1x0
7-14
00001x3x2x1x0
15-30
000001x4x3x2x1x0
31-62
…
…
Table 92illustratesexplicitlytheassignmentofbitstringstocodeNumvalues.
Table 92–Exp-GolombbitstringsandcodeNuminexplicitformandusedasue（v）（informative）
Bitstring
codeNum
1
0
010
1
011
2
00100
3
00101
4
00110
5
00111
6
0001000
7
0001001
8
0001010
9
…
…
Dependingonthedescriptor,thevalueofasyntaxelementisderivedasfollows.
-Ifthesyntaxelementiscodedasue（v）,thevalueofthesyntaxelementisequaltocodeNum.
-Otherwise,ifthesyntaxelementiscodedasse（v）,thevalueofthesyntaxelementisderivedbyinvokingthemappingprocessforsignedExp-Golombcodesasspecifiedinsubclause9.1.1withcodeNumastheinput.
-Otherwise,ifthesyntaxelementiscodedasme（v）,thevalueofthesyntaxelementisderivedbyinvokingthemappingprocessforcodedblockpatternasspecifiedinsubclause9.1.2withcodeNumastheinput.
-Otherwise（thesyntaxelementiscodedaste（v））,therangeofthesyntaxelementshallbedeterminedfirst.Therangeofthissyntaxelementmaybebetween0andx,withxbeinggreaterthanorequalto 1andisusedinthederivationofthevalueofasyntaxelementasfollows
-Ifxisgreaterthan 1,codeNumandthevalueofthesyntaxelementshallbederivedinthesamewayasforsyntaxelementscodedasue（v）
-Otherwise（xisequalto 1）,theparsingprocessforcodeNumwhichisequaltothevalueofthesyntaxelementisgivenbyaprocessequivalentto:
b=read_bits
（1）
codeNum=!
b
9.1.1MappingprocessforsignedExp-Golombcodes
InputtothisprocessiscodeNumasspecifiedinsubclause9.1.
Outputofthisprocessisavalueofasyntaxelementcodedasse（v）.
ThesyntaxelementisassignedtothecodeNumbyorderingthesyntaxelementbyitsabsolutevalueinincreasingorderandrepresentingthepositivevalueforagivenabsolutevaluewiththelowercodeNum.Table 93providestheassignmentrule.
Table 93–AssignmentofsyntaxelementtocodeNumforsignedExp-Golombcodedsyntaxelementsse（v）
codeNum
syntaxelementvalue
0
0
1
1
2
–1
3
2
4
–2
5
3
6
–3
k
（–1）k+1Ceil（k÷2）
9.1.2Mappingprocessforcodedblockpattern
InputtothisprocessiscodeNumasspecifiedinsubclause9.1.
Outputofthisprocessisavalueofthesyntaxelementcoded_block_patterncodedasme（v）.
Table 94showstheassignmentofcoded_block_patterntocodeNumdependingonwhetherthemacroblockpredictionmodeisequaltoIntra_4x4orInter.
Table 94–AssignmentofcodeNumtovaluesofcoded_block_patternformacroblockpredictionmodes
codeNum
coded_block_pattern
Intra_4x4
Inter
0
47
0
1
31
16
2
15
1
3
0
2
4
23
4
5
27
8
6
29
32
7
30
3
8
7
5
9
11
10
10
13
12
11
14
15
12
39
47
13
43
7
14
45
11
15
46
13
16
16
14
17
3
6
18
5
9
19
10
31
20
12
35
21
19
37
22
21
42
23
26
44
24
28
33
25
35
34
26
37
36
27
42
40
28
44
39
29
1
43
30
2
45
31
4
46
32
8
17
33
17
18
34
18
20
35
20
24
36
24
19
37
6
21
38
9
26
39
22
28
40
25
23
41
32
27
42
33
29
43
34
30
44
36
22
45
40
25
46
38
38
47
41
41
9.2CAVLCparsingprocessfortransformcoefficientlevels
Thisprocessisinvokedwhenparsingsyntaxelementswithdescriptorequalto ce（v）insubclause7.3.5.3.1andwhenentropy_coding_mode_flagisequalto 0.
Inputstothisprocessarebitsfromslicedata,amaximumnumberofnon-zerotransformcoefficientlevelsmaxNumCoeff,thelumablockindexluma4x4BlkIdxorthechromablockindexchroma4x4BlkIdxofthecurrentblockoftransformcoefficientlevels.
OutputofthisprocessisthelistcoeffLevelcontainingtransformcoefficientlevelsofthelumablockwithblockindexluma4x4BlkIdxorthechromablockwithblockindexchroma4x4BlkIdx.
Theprocessisspecifiedinthefollowingorderedsteps:
1.Alltransformcoefficientlevels,withindicesfrom0tomaxNumCoeff-1,inthelistcoeffLevelaresetequalto 0.
2.Thetotalnumberofnon-zerotransformcoefficientlevelsTotalCoeff（ coeff_token ）andthenumberoftrailingonetransformcoefficientlevelsTrailingOnes（ coeff_token ）arederivedbyparsingcoeff_token（seesubclause9.2.1）asfollows.
-Ifthenumberofnon-zerotransformcoefficientlevelsTotalCoeff（ coeff_token ）isequalto 0,thelistcoeffLevelcontaining0valuesisreturnedandnofurtherstepiscarriedout.
-Otherwise,thefollowingstepsarecarriedout.
a.Thenon-zerotransformcoefficientlevelsarederivedbyparsingtrailing_ones_sign_flag,level_prefix,andlevel_suffix（seesubclause9.2.2）.
b.Therunsofzerotransformcoefficientlevelsbeforeeachnon-zerotransformcoefficientlevelarederivedbyparsingtotal_zerosandrun_before（seesubclause9.2.3）.
c.ThelevelandruninformationarecombinedintothelistcoeffLevel（seesubclause9.2.4）.
9.2.1Parsingprocessfortotalnumberoftransformcoefficientlevelsandtrailingones
Inputstothisprocessarebitsfromslicedata,amaximumnumberofnon-zerotransformcoefficientlevelsmaxNumCoeff,thelumablockindexluma4x4BlkIdxorthechromablockindexchroma4x4BlkIdxofthecurrentblockoftransform.
OutputsofthisprocessareTotalCoeff（ coeff_token ）andTrailingOnes（ coeff_token ）.
Thesyntaxelementcoeff_tokenisdecodedusingoneofthefiveVLCsspecifiedinfiveright-mostcolumnsofTable 95.EachVLCspecifiesbothTotalCoeff（ coeff_token ）andTrailingOnes（ coeff_token ）foragivencodewordcoeff_token.VLCselectionisdependentuponavariablenCthatisderivedasfollows.
-IftheCAVLCparsingprocessisinvokedforChromaDCLevel,nCissetequalto –1,
-Otherwise,thefollowingapplies.
-WhentheCAVLCparsingprocessisinvokedforIntra16x16DCLevel,luma4x4BlkIdxissetequalto 0.
-ThevariablesblkAandblkBarederivedasfollows.
-IftheCAVLCparsingprocessisinvokedforIntra16x16DCLevel,Intra16x16ACLevel,orLumaLevel,theprocessspecifiedinsubclause6.4.7.3isinvokedwithluma4x4BlkIdxastheinput,andtheoutputisassignedtombAddrA,mbAddrB,luma4x4BlkIdxA,andluma4x4BlkIdxB.The4x4lumablockspecifiedbymbAddrA\luma4x4BlkIdxAisassignedto blkA,andthe4x4lumablockspecifiedbymbAddrB\luma4x4BlkIdxBisassignedto blkB.
-Otherwise（theCAVLCparsingprocessisinvokedforChromaACLevel）,theprocessspecifiedinsubclause6.4.7.4isinvokedwithchroma4x4BlkIdxasinput,andtheoutputisassignedtombAddrA,mbAddrB,chroma4x4BlkIdxA,andchroma4x4BlkIdxB.The4x4chromablockspecifiedbymbAddrA\iCbCr\chroma4x4BlkIdxAisassignedto blkA,andthe4x4chromablockspecifiedbymbAddrB\iCbCr\luma4x4BlkIdxBisassignedto blkB.
-LetnAandnBbethenumberofnon-zerotransformcoefficientlevels（givenbyTotalCoeff（ coeff_token ））intheblockoftransformcoefficientlevelsblkAlocatedtotheleftofthecurrentblockandtheblockoftransformcoefficientlevelsblkBlocatedabovethecurrentblock,respectively.
-WithNreplacedbyAandB,inmbAddrN,blkN,andnNthefollowingapplies.
-Ifanyofthefollowingconditionsistrue,nNissetequalto 0.
-mbAddrNisnotavailable
-ThecurrentmacroblockiscodedusinganIntrapredictionmode,constrained_intra_pred_flagisequalto 1andmbAddrNiscodedusingInterpredictionandslicedatapartitioningisinuse（nal_unit_typeisintherangeof2to 4,inclusive）.
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