Understanding VC-1

There is a WMV9/VC-1 reference decoder available on the internet which answers to the filename vc1_reference_decoder_release6.zip. This section of the MultimediaWiki is an effort to create an open VC-1 specification based on that reference implementation.

These functions are necessary for processing VC-1 data using the reference decoder:

// set up pointers to bitstream (extradata) in internal state structure
vc1DECBIT_InitialiseBitstream

// analyze how much memory the client app needs to allocate
vc1DEC_DecoderRequirements

// init decoder
vc1DEC_DecoderInitialise

// process the extradata setup bitstream
vc1DEC_DecodeSequence

// decode a frame
vc1DEC_DecodeFrame

These are the call trees for the above functions

vc1DECBIT_InitialiseBitstream
 +- vc1DECBIT_ReadBytes

vc1DEC_DecoderRequirements
 +- vc1DECBIT_GetBits
 +- vc1TOOLS_InitReferencePicture
   +- vc1TOOLS_InitImagePosition

vc1DEC_DecoderInitialise
 +- vc1DEC_SetMaxSize
 +- vc1TOOLS_InitReferencePicture

vc1DEC_DecodeSequence
 +- vc1DECSEQ_UnpackSequenceLayer
   +- vc1DECBIT_GetBits

vc1DEC_DecodeFrame
 +- vc1DECPIC_UnpackPictureLayer
   +- vc1DECPIC_ReadPictureLayer
     +- vc1DECBIT_GetBits
     +- vc1DECPIC_SetDimensionsInMB
     +- vc1DECPIC_UnpackPictureLayerAdvanced
       +- vc1DECBIT_GetBits
       +- vc1DECBIT_GetVLC
       +- vc1DECPIC_UnpackPanScanParams
         +- vc1DECBIT_GetBits        
     +- vc1DECPIC_UnpackPictureLayerSimpleMain
       +- vc1DECBIT_BitCountGet
       +- vc1DECBIT_GetBits
       +- vc1DECBIT_GetVLC
       +- vc1DECPIC_UnpackQuantizationParams
         +- vc1DECBIT_GetBits
         +- vc1IQUANT_GetQuantizer
       +- vc1DECPIC_SetDimensionsInMB
       +- vc1DECBITPL_ReadBitplane
         +- vc1DECBIT_GetBits
         +- vc1DECBIT_GetVLC
         +- vc1DECBITPL_DecodeNorm2Bits
           +- vc1DECBIT_GetBits
           +- vc1DECBIT_GetVLC
         +- vc1DECBITPL_DecodeNorm6Bits
           +- vc1DECBIT_GetBits
           +- vc1DECBIT_GetVLC
         +- vc1DECBITPL_DecodeRowskipBits
           +- vc1DECBIT_GetBits
         +- vc1DECBITPL_DecodeColskipBits
           +- vc1DECBIT_GetBits
         +- vc1DECBITPL_DecodeRawBits
       +- vc1DECPIC_UnpackVOPDQUANTParams
         +- vc1DECBIT_GetBits
   +- vc1DECPIC_UnpackFieldPictureLayer
     +- vc1DECPIC_ReadAdvancedPictureLayer
       +- vc1DECPIC_UnpackFieldPictureLayerIAdvanced
         +- vc1DECPIC_UnpackQuantizationParams
         +- vc1DECBIT_GetBits
         +- vc1DECBITPL_ReadBitplane
         +- vc1DECBIT_GetVLC
         +- vc1DECPIC_UnpackVOPDQUANTParams
       +- vc1DECPIC_UnpackFieldPictureLayerPBAdvanced
         +- vc1DECPIC_UnpackQuantizationParams
         +- vc1DECBIT_GetBits
         +- vc1DECBIT_GetVLC
         +- vc1DECPIC_UnpackInterlaceMVModeParams
         +- vc1DECBITPL_ReadBitplane
     +- vc1DECPIC_DisplayPicture
       +- vc1DECPIC_DisplayField
         +- vc1DECPIC_InitialiseAppPicture
         +- vc1TOOLS_ResolutionUpsample
     +- vc1TOOLS_InitReferencePicture
     +- vc1TOOLS_NewReference
     +- vc1TOOLS_CopyReference
     +- vc1TOOLS_ICPadReferencePicture
       +- vc1TOOLS_RangeReduceReference
         +- vc1TOOLS_RangeReduce16
         +- vc1TOOLS_RangeExpand
       +- vc1TOOLS_IntensityCompensate
         +- vc1TOOLS_ICComponent
       +- vc1TOOLS_PadReferencePicture
         +- vc1TOOLS_PadComponent
     +- vc1SCALEMV_InitScaleMV
     +- vc1DECSLICE_DecodeSlice
       +- vc1DECBIT_GetBits
       +- vc1DECPIC_UnpackSyncmarker
         +- vc1DECBIT_AlignBit
           +- vc1DECBIT_ReadBytes
         +- vc1DECBIT_GetBits
       +- vc1DECMB_UnpackMacroblockLayer
         +- vc1IQUANT_ChooseQuantizer
         +- vc1DECMB_UnpackMacroblockI
           +- vc1DECBITPL_ReadBitplaneBit
             +- vc1DECBIT_GetBits
           +- vc1DECBIT_GetVLC
           +- vc1PREDCBP_ApplyCBPCYPred
           +- vc1DECBIT_GetBits
           +- vc1DECMB_UnpackMBQuantParams
             +- vc1DECBIT_GetBits
         +- vc1DECMB_UnpackMacroblockProgP
           +- vc1DECBITPL_ReadBitplaneBit
           +- vc1DECMB_UnpackMacroblockProgPSkipped
             +- vc1DECBIT_LookBits
               +- vc1DECBIT_ReadBits
             +- vc1PREDMV_PredictProgressiveMV
               +- vc1PRED_pTopBlk
               +- vc1PRED_pLeftBlk
               +- vc1PRED_pB1MVBlk
               +- vc1PRED_pB4MVBlk
               +- vc1TOOLS_Median3
               +- vc1CROPMV_BPredPullBack
             +- vc1DECBIT_GetBits
             +- vc1DECMV_ApplyMVPrediction
             +- vc1DERIVEMV_DecideChromaBlockType
           +- vc1DECMB_UnpackMacroblockProgP1MV
             +- vc1DECMV_UnpackMVData
             +- vc1DECBIT_LookBits
             +- vc1PREDMV_PredictProgressiveMV
             +- vc1DECBIT_GetBits
             +- vc1DECMV_ApplyMVPrediction
             +- vc1DERIVEMV_DecideChromaBlockType
             +- vc1DECMB_UnpackMBQuantParams
             +- vc1DECBIT_GetVLC
             +- vc1DECMB_DecodeTransformInfo
               +- vc1DECMB_UnpackTTMB
                 +- vc1DECBIT_GetVLC
           +- vc1DECMB_UnpackMacroblockProgP4MV
             +- vc1DECBIT_GetVLC
             +- vc1DECMV_UnpackMVData
             +- vc1DECBIT_LookBits
             +- vc1PREDMV_PredictProgressiveMV
             +- vc1DECBIT_GetBits
             +- vc1DECMV_ApplyMVPrediction
             +- vc1DERIVEMV_DecideChromaBlockType
             +- vc1DECMB_UnpackMBQuantParams
             +- vc1PREDDCAC_ACPREDPresent
             +- vc1DECMB_DecodeTransformInfo
         +- vc1DECMB_UnpackMacroblockFieldP
           +- vc1DECBIT_GetVLC
           +- vc1DECMV_UnpackMVDataInterlace
             +- vc1DECBIT_GetVLC
             +- vc1DECBIT_GetBits
           +- vc1DECBIT_LookBits
           +- vc1PREDMV_PredictInterlacedFieldMV
             +- vc1SCALEMV_ScaleMV
             +- vc1TOOLS_Median3
           +- vc1DECBIT_GetBits
           +- vc1DECMV_ApplyMVPrediction
           +- vc1DERIVEMV_DecideChromaBlockType
           +- vc1DECMB_UnpackMBQuantParams
           +- vc1DECMB_DecodeTransformInfo
         +- vc1DECMB_UnpackMacroblockFrameP
           +- vc1DECBITPL_ReadBitplaneBit
           +- vc1PREDMV_PredictInterlacedFrameMV
             +- vc1PREDMV_FrameMBPred
             +- vc1TOOLS_Median3
           +- vc1DECMV_ApplyMVPrediction
           +- vc1DECBIT_GetVLC
           +- vc1DECBIT_GetBits
           +- vc1DERIVEMV_DecideChromaBlockType
           +- vc1DECMB_UnpackMBQuantParams
           +- vc1DECMV_UnpackMVDataInterlace
         +- vc1DECMB_UnpackMacroblockProgB
           +- vc1DECBITPL_ReadBitplaneBit
           +- vc1DECMV_UnpackMVData
           +- vc1DECBIT_GetVLC
           +- vc1DECMB_UnpackMBQuantParams
           +- vc1DECBIT_GetBits
           +- vc1PREDMV_PredictProgressiveMV
           +- vc1DECMV_ApplyMVPrediction
           +- vc1DERIVEMV_DecideChromaBlockType
           +- vc1DECMB_DecodeTransformInfo
         +- vc1DECMB_UnpackMacroblockFieldB
           +- vc1DECBIT_GetVLC
           +- vc1DECBITPL_ReadBitplaneBit
           +- vc1DECBITPL_SkipBitplaneBit
           +- vc1DECBIT_GetBits
           +- vc1DECMV_UnpackMVDataInterlace
           +- vc1PREDMV_PredictInterlacedFieldMV
           +- vc1DECMV_ApplyMVPrediction
           +- vc1DECMB_UnpackMBQuantParams
           +- vc1DERIVEMV_DecideChromaBlockType
           +- vc1DECMB_DecodeTransformInfo
         +- vc1DECMB_UnpackMacroblockFrameB
           +- vc1DECBITPL_ReadBitplaneBit
           +- vc1DECBIT_GetVLC
           +- vc1DECBITPL_SkipBitplaneBit
           +- vc1DECBIT_GetBits
           +- vc1DECMB_UnpackMBQuantParams
           +- vc1DERIVEMV_DecideChromaBlockType
           +- vc1DECMV_UnpackMVDataInterlace
           +- vc1PREDMV_PredictInterlacedFrameMV
           +- vc1DECMV_ApplyMVPrediction
         +- vc1DECMB_AssignCodedBlockPattern
         +- vc1DECBLK_DecodeBlockLayer
           +- vc1DECBLK_UnpackIntraBlock
             +- vc1PREDDCAC_DCDefault
               +- vc1PREDDCAC_DCStepSize
             +- vc1PREDDCAC_PredictDCAC
               +- vc1PREDDCAC_GetQuant
               +- vc1PREDDCAC_ScaleDC
                 +- vc1PREDDCAC_DCStepSize
             +- vc1DECBLK_UnpackDCDifferential
               +- vc1DECBIT_GetVLC
               +- vc1DECBIT_GetBits
             +- vc1DEC3DH_DecodeACRunLevel
               +- vc1DEC3DH_ChooseACCodingSet
               +- vc1DEC3DH_ChooseEscapeMode3Table
               +- vc1DEC3DH_UnpackTransformACCoef
                 +- vc1DECBIT_GetVLC
                 +- vc1DECBIT_GetBits
             +- vc1DECZZ_DeZigZagBlock
               +- vc1DECZZ_DeZigZag
             +- vc1DECBLK_ApplyACPrediction
             +- vc1PREDDCAC_CopyDCAC
           +- vc1DECBLK_UnpackInterBlock
             +- vc1DECBLK_UnpackSubBlockPattern
               +- vc1DECBIT_GetVLC
             +- vc1DECBLK_UnpackTTBLK
               +- vc1DECBIT_GetVLC
             +- vc1DEC3DH_DecodeACRunLevel
             +- vc1DECZZ_DeZigZagBlock
           +- vc1INTERP_PredictMB
             +- vc1DERIVEMV_StoreMotionVectors
             +- vc1DERIVEMV_DeriveMV
               +- vc1DERIVEMV_DirectMV
                 +- vc1DERIVEMV_DeriveProgMV
                   +- vc1TOOLS_Median3
                   +- vc1TOOLS_Median4
                 +- vc1CROPMV_ChromaPullBack
                 +- vc1DERIVEMV_DeriveIntFieldMV
                   +- vc1TOOLS_Median4
                   +- vc1TOOLS_Median3
                 +- vc1DERIVEMV_DeriveIntFrameDirectMV
                 +- vc1CROPMV_PPredPullBack
               +- vc1DERIVEMV_FillInInterlaceFieldMV
                 +- vc1PREDMV_PredictInterlacedFieldMV
                   +- vc1SCALEMV_ScaleMV
                   +- vc1TOOLS_Median3
             +- vc1INTERP_InterpolateBlock
               +- vc1CROPMV_LumaPullBack
               +- vc1DERIVEMV_DeriveChromaMV
                 +- vc1DERIVEMV_DeriveProgMV
                 +- vc1CROPMV_LumaPullBack
                 +- vc1DERIVEMV_DeriveSecondStageChromaMV
                   +- vc1CROPMV_ChromaPullBack
                 +- vc1DERIVEMV_DeriveIntFieldMV
                   +- vc1TOOLS_Median4
               +- vc1CROPMV_ChromaPullBack
               +- vc1INTERP_InterpPatchQuarterPelBilinear
               +- vc1INTERP_InterpPatchHalfPelBilinear
                 +- vc1INTERP_InterpPatchQuarterPelBilinear
               +- vc1INTERP_InterpPatchQuarterPelBicubic
                 +- vc1INTERP_CopyPatch
                 +- vc1INTERP_InterpPatchQuarterPelBicubicVert
                 +- vc1INTERP_InterpPatchQuarterPelBicubicHoriz
                 +- vc1INTERP_InterpPatchQuarterPelBicubicDiag
               +- vc1INTERP_InterpPatchHalfPelBicubic
                 +- vc1INTERP_InterpPatchQuarterPelBicubic
             +- vc1INTERP_AverageBlocks
           +- vc1RECON_ReconstructMB
             +- vc1IQUANT_InverseACQuantize
             +- vc1IQUANT_InverseDCQuantize
               +- vc1PREDDCAC_DCStepSize
             +- vc1ITRANS_InverseTransformBlock
               +- vc1ITRANS_InverseTransform_AnnexA1
             +- vc1RECON_ApplyPredictionAndCopyMB
               +- vc1INTERP_InterlaceDiffMB
               +- vc1INTERP_InterlacePredMB
               +- vc1SMOOTH_OverlapSmoothMB
                 +- vc1PRED_pLeftMB
                 +- vc1TOOLS_GetPictureDestination
                 +- vc1SMOOTH_OverlapSmoothVertBlk
                 +- vc1SMOOTH_OverlapSmoothHorizMB
                   +- vc1TOOLS_GetPictureDestination
                   +- vc1SMOOTH_OverlapSmoothHorizBlk
               +- vc1TOOLS_GetPictureDestination
               +- vc1SMOOTH_OverlapSmoothHorizMB
       +- vc1DEBLOCK_DeblockSlice
         +- vc1DEBLOCK_HorizDeblockMB
           +- vc1TOOLS_GetPictureDestination
           +- vc1DEBLOCK_HorizDeblockBlk
         +- vc1DEBLOCK_VertDeblockMB
           +- vc1TOOLS_GetPictureDestination
           +- vc1DEBLOCK_VertDeblockBlk
       +- vc1TOOLS_CopyReference
       +- vc1DECPIC_DisplayPicture