From e1e8d058a33f7566f9c565d04b0d8b56f9645c35 Mon Sep 17 00:00:00 2001 From: Dimitri Sokolyuk Date: Wed, 25 Apr 2018 09:28:54 +0200 Subject: add vendor --- vendor/golang.org/x/image/vp8/reconstruct.go | 442 +++++++++++++++++++++++++++ 1 file changed, 442 insertions(+) create mode 100644 vendor/golang.org/x/image/vp8/reconstruct.go (limited to 'vendor/golang.org/x/image/vp8/reconstruct.go') diff --git a/vendor/golang.org/x/image/vp8/reconstruct.go b/vendor/golang.org/x/image/vp8/reconstruct.go new file mode 100644 index 0000000..c1cc4b5 --- /dev/null +++ b/vendor/golang.org/x/image/vp8/reconstruct.go @@ -0,0 +1,442 @@ +// Copyright 2011 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package vp8 + +// This file implements decoding DCT/WHT residual coefficients and +// reconstructing YCbCr data equal to predicted values plus residuals. +// +// There are 1*16*16 + 2*8*8 + 1*4*4 coefficients per macroblock: +// - 1*16*16 luma DCT coefficients, +// - 2*8*8 chroma DCT coefficients, and +// - 1*4*4 luma WHT coefficients. +// Coefficients are read in lots of 16, and the later coefficients in each lot +// are often zero. +// +// The YCbCr data consists of 1*16*16 luma values and 2*8*8 chroma values, +// plus previously decoded values along the top and left borders. The combined +// values are laid out as a [1+16+1+8][32]uint8 so that vertically adjacent +// samples are 32 bytes apart. In detail, the layout is: +// +// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +// . . . . . . . a b b b b b b b b b b b b b b b b c c c c . . . . 0 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 1 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 2 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 3 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y c c c c . . . . 4 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 5 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 6 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 7 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y c c c c . . . . 8 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 9 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 10 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 11 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y c c c c . . . . 12 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 13 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 14 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 15 +// . . . . . . . d Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y . . . . . . . . 16 +// . . . . . . . e f f f f f f f f . . . . . . . g h h h h h h h h 17 +// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 18 +// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 19 +// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 20 +// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 21 +// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 22 +// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 23 +// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 24 +// . . . . . . . i B B B B B B B B . . . . . . . j R R R R R R R R 25 +// +// Y, B and R are the reconstructed luma (Y) and chroma (B, R) values. +// The Y values are predicted (either as one 16x16 region or 16 4x4 regions) +// based on the row above's Y values (some combination of {abc} or {dYC}) and +// the column left's Y values (either {ad} or {bY}). Similarly, B and R values +// are predicted on the row above and column left of their respective 8x8 +// region: {efi} for B, {ghj} for R. +// +// For uppermost macroblocks (i.e. those with mby == 0), the {abcefgh} values +// are initialized to 0x81. Otherwise, they are copied from the bottom row of +// the macroblock above. The {c} values are then duplicated from row 0 to rows +// 4, 8 and 12 of the ybr workspace. +// Similarly, for leftmost macroblocks (i.e. those with mbx == 0), the {adeigj} +// values are initialized to 0x7f. Otherwise, they are copied from the right +// column of the macroblock to the left. +// For the top-left macroblock (with mby == 0 && mbx == 0), {aeg} is 0x81. +// +// When moving from one macroblock to the next horizontally, the {adeigj} +// values can simply be copied from the workspace to itself, shifted by 8 or +// 16 columns. When moving from one macroblock to the next vertically, +// filtering can occur and hence the row values have to be copied from the +// post-filtered image instead of the pre-filtered workspace. + +const ( + bCoeffBase = 1*16*16 + 0*8*8 + rCoeffBase = 1*16*16 + 1*8*8 + whtCoeffBase = 1*16*16 + 2*8*8 +) + +const ( + ybrYX = 8 + ybrYY = 1 + ybrBX = 8 + ybrBY = 18 + ybrRX = 24 + ybrRY = 18 +) + +// prepareYBR prepares the {abcdefghij} elements of ybr. +func (d *Decoder) prepareYBR(mbx, mby int) { + if mbx == 0 { + for y := 0; y < 17; y++ { + d.ybr[y][7] = 0x81 + } + for y := 17; y < 26; y++ { + d.ybr[y][7] = 0x81 + d.ybr[y][23] = 0x81 + } + } else { + for y := 0; y < 17; y++ { + d.ybr[y][7] = d.ybr[y][7+16] + } + for y := 17; y < 26; y++ { + d.ybr[y][7] = d.ybr[y][15] + d.ybr[y][23] = d.ybr[y][31] + } + } + if mby == 0 { + for x := 7; x < 28; x++ { + d.ybr[0][x] = 0x7f + } + for x := 7; x < 16; x++ { + d.ybr[17][x] = 0x7f + } + for x := 23; x < 32; x++ { + d.ybr[17][x] = 0x7f + } + } else { + for i := 0; i < 16; i++ { + d.ybr[0][8+i] = d.img.Y[(16*mby-1)*d.img.YStride+16*mbx+i] + } + for i := 0; i < 8; i++ { + d.ybr[17][8+i] = d.img.Cb[(8*mby-1)*d.img.CStride+8*mbx+i] + } + for i := 0; i < 8; i++ { + d.ybr[17][24+i] = d.img.Cr[(8*mby-1)*d.img.CStride+8*mbx+i] + } + if mbx == d.mbw-1 { + for i := 16; i < 20; i++ { + d.ybr[0][8+i] = d.img.Y[(16*mby-1)*d.img.YStride+16*mbx+15] + } + } else { + for i := 16; i < 20; i++ { + d.ybr[0][8+i] = d.img.Y[(16*mby-1)*d.img.YStride+16*mbx+i] + } + } + } + for y := 4; y < 16; y += 4 { + d.ybr[y][24] = d.ybr[0][24] + d.ybr[y][25] = d.ybr[0][25] + d.ybr[y][26] = d.ybr[0][26] + d.ybr[y][27] = d.ybr[0][27] + } +} + +// btou converts a bool to a 0/1 value. +func btou(b bool) uint8 { + if b { + return 1 + } + return 0 +} + +// pack packs four 0/1 values into four bits of a uint32. +func pack(x [4]uint8, shift int) uint32 { + u := uint32(x[0])<<0 | uint32(x[1])<<1 | uint32(x[2])<<2 | uint32(x[3])<<3 + return u << uint(shift) +} + +// unpack unpacks four 0/1 values from a four-bit value. +var unpack = [16][4]uint8{ + {0, 0, 0, 0}, + {1, 0, 0, 0}, + {0, 1, 0, 0}, + {1, 1, 0, 0}, + {0, 0, 1, 0}, + {1, 0, 1, 0}, + {0, 1, 1, 0}, + {1, 1, 1, 0}, + {0, 0, 0, 1}, + {1, 0, 0, 1}, + {0, 1, 0, 1}, + {1, 1, 0, 1}, + {0, 0, 1, 1}, + {1, 0, 1, 1}, + {0, 1, 1, 1}, + {1, 1, 1, 1}, +} + +var ( + // The mapping from 4x4 region position to band is specified in section 13.3. + bands = [17]uint8{0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 0} + // Category probabilties are specified in section 13.2. + // Decoding categories 1 and 2 are done inline. + cat3456 = [4][12]uint8{ + {173, 148, 140, 0, 0, 0, 0, 0, 0, 0, 0, 0}, + {176, 155, 140, 135, 0, 0, 0, 0, 0, 0, 0, 0}, + {180, 157, 141, 134, 130, 0, 0, 0, 0, 0, 0, 0}, + {254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129, 0}, + } + // The zigzag order is: + // 0 1 5 6 + // 2 4 7 12 + // 3 8 11 13 + // 9 10 14 15 + zigzag = [16]uint8{0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15} +) + +// parseResiduals4 parses a 4x4 region of residual coefficients, as specified +// in section 13.3, and returns a 0/1 value indicating whether there was at +// least one non-zero coefficient. +// r is the partition to read bits from. +// plane and context describe which token probability table to use. context is +// either 0, 1 or 2, and equals how many of the macroblock left and macroblock +// above have non-zero coefficients. +// quant are the DC/AC quantization factors. +// skipFirstCoeff is whether the DC coefficient has already been parsed. +// coeffBase is the base index of d.coeff to write to. +func (d *Decoder) parseResiduals4(r *partition, plane int, context uint8, quant [2]uint16, skipFirstCoeff bool, coeffBase int) uint8 { + prob, n := &d.tokenProb[plane], 0 + if skipFirstCoeff { + n = 1 + } + p := prob[bands[n]][context] + if !r.readBit(p[0]) { + return 0 + } + for n != 16 { + n++ + if !r.readBit(p[1]) { + p = prob[bands[n]][0] + continue + } + var v uint32 + if !r.readBit(p[2]) { + v = 1 + p = prob[bands[n]][1] + } else { + if !r.readBit(p[3]) { + if !r.readBit(p[4]) { + v = 2 + } else { + v = 3 + r.readUint(p[5], 1) + } + } else if !r.readBit(p[6]) { + if !r.readBit(p[7]) { + // Category 1. + v = 5 + r.readUint(159, 1) + } else { + // Category 2. + v = 7 + 2*r.readUint(165, 1) + r.readUint(145, 1) + } + } else { + // Categories 3, 4, 5 or 6. + b1 := r.readUint(p[8], 1) + b0 := r.readUint(p[9+b1], 1) + cat := 2*b1 + b0 + tab := &cat3456[cat] + v = 0 + for i := 0; tab[i] != 0; i++ { + v *= 2 + v += r.readUint(tab[i], 1) + } + v += 3 + (8 << cat) + } + p = prob[bands[n]][2] + } + z := zigzag[n-1] + c := int32(v) * int32(quant[btou(z > 0)]) + if r.readBit(uniformProb) { + c = -c + } + d.coeff[coeffBase+int(z)] = int16(c) + if n == 16 || !r.readBit(p[0]) { + return 1 + } + } + return 1 +} + +// parseResiduals parses the residuals and returns whether inner loop filtering +// should be skipped for this macroblock. +func (d *Decoder) parseResiduals(mbx, mby int) (skip bool) { + partition := &d.op[mby&(d.nOP-1)] + plane := planeY1SansY2 + quant := &d.quant[d.segment] + + // Parse the DC coefficient of each 4x4 luma region. + if d.usePredY16 { + nz := d.parseResiduals4(partition, planeY2, d.leftMB.nzY16+d.upMB[mbx].nzY16, quant.y2, false, whtCoeffBase) + d.leftMB.nzY16 = nz + d.upMB[mbx].nzY16 = nz + d.inverseWHT16() + plane = planeY1WithY2 + } + + var ( + nzDC, nzAC [4]uint8 + nzDCMask, nzACMask uint32 + coeffBase int + ) + + // Parse the luma coefficients. + lnz := unpack[d.leftMB.nzMask&0x0f] + unz := unpack[d.upMB[mbx].nzMask&0x0f] + for y := 0; y < 4; y++ { + nz := lnz[y] + for x := 0; x < 4; x++ { + nz = d.parseResiduals4(partition, plane, nz+unz[x], quant.y1, d.usePredY16, coeffBase) + unz[x] = nz + nzAC[x] = nz + nzDC[x] = btou(d.coeff[coeffBase] != 0) + coeffBase += 16 + } + lnz[y] = nz + nzDCMask |= pack(nzDC, y*4) + nzACMask |= pack(nzAC, y*4) + } + lnzMask := pack(lnz, 0) + unzMask := pack(unz, 0) + + // Parse the chroma coefficients. + lnz = unpack[d.leftMB.nzMask>>4] + unz = unpack[d.upMB[mbx].nzMask>>4] + for c := 0; c < 4; c += 2 { + for y := 0; y < 2; y++ { + nz := lnz[y+c] + for x := 0; x < 2; x++ { + nz = d.parseResiduals4(partition, planeUV, nz+unz[x+c], quant.uv, false, coeffBase) + unz[x+c] = nz + nzAC[y*2+x] = nz + nzDC[y*2+x] = btou(d.coeff[coeffBase] != 0) + coeffBase += 16 + } + lnz[y+c] = nz + } + nzDCMask |= pack(nzDC, 16+c*2) + nzACMask |= pack(nzAC, 16+c*2) + } + lnzMask |= pack(lnz, 4) + unzMask |= pack(unz, 4) + + // Save decoder state. + d.leftMB.nzMask = uint8(lnzMask) + d.upMB[mbx].nzMask = uint8(unzMask) + d.nzDCMask = nzDCMask + d.nzACMask = nzACMask + + // Section 15.1 of the spec says that "Steps 2 and 4 [of the loop filter] + // are skipped... [if] there is no DCT coefficient coded for the whole + // macroblock." + return nzDCMask == 0 && nzACMask == 0 +} + +// reconstructMacroblock applies the predictor functions and adds the inverse- +// DCT transformed residuals to recover the YCbCr data. +func (d *Decoder) reconstructMacroblock(mbx, mby int) { + if d.usePredY16 { + p := checkTopLeftPred(mbx, mby, d.predY16) + predFunc16[p](d, 1, 8) + for j := 0; j < 4; j++ { + for i := 0; i < 4; i++ { + n := 4*j + i + y := 4*j + 1 + x := 4*i + 8 + mask := uint32(1) << uint(n) + if d.nzACMask&mask != 0 { + d.inverseDCT4(y, x, 16*n) + } else if d.nzDCMask&mask != 0 { + d.inverseDCT4DCOnly(y, x, 16*n) + } + } + } + } else { + for j := 0; j < 4; j++ { + for i := 0; i < 4; i++ { + n := 4*j + i + y := 4*j + 1 + x := 4*i + 8 + predFunc4[d.predY4[j][i]](d, y, x) + mask := uint32(1) << uint(n) + if d.nzACMask&mask != 0 { + d.inverseDCT4(y, x, 16*n) + } else if d.nzDCMask&mask != 0 { + d.inverseDCT4DCOnly(y, x, 16*n) + } + } + } + } + p := checkTopLeftPred(mbx, mby, d.predC8) + predFunc8[p](d, ybrBY, ybrBX) + if d.nzACMask&0x0f0000 != 0 { + d.inverseDCT8(ybrBY, ybrBX, bCoeffBase) + } else if d.nzDCMask&0x0f0000 != 0 { + d.inverseDCT8DCOnly(ybrBY, ybrBX, bCoeffBase) + } + predFunc8[p](d, ybrRY, ybrRX) + if d.nzACMask&0xf00000 != 0 { + d.inverseDCT8(ybrRY, ybrRX, rCoeffBase) + } else if d.nzDCMask&0xf00000 != 0 { + d.inverseDCT8DCOnly(ybrRY, ybrRX, rCoeffBase) + } +} + +// reconstruct reconstructs one macroblock and returns whether inner loop +// filtering should be skipped for it. +func (d *Decoder) reconstruct(mbx, mby int) (skip bool) { + if d.segmentHeader.updateMap { + if !d.fp.readBit(d.segmentHeader.prob[0]) { + d.segment = int(d.fp.readUint(d.segmentHeader.prob[1], 1)) + } else { + d.segment = int(d.fp.readUint(d.segmentHeader.prob[2], 1)) + 2 + } + } + if d.useSkipProb { + skip = d.fp.readBit(d.skipProb) + } + // Prepare the workspace. + for i := range d.coeff { + d.coeff[i] = 0 + } + d.prepareYBR(mbx, mby) + // Parse the predictor modes. + d.usePredY16 = d.fp.readBit(145) + if d.usePredY16 { + d.parsePredModeY16(mbx) + } else { + d.parsePredModeY4(mbx) + } + d.parsePredModeC8() + // Parse the residuals. + if !skip { + skip = d.parseResiduals(mbx, mby) + } else { + if d.usePredY16 { + d.leftMB.nzY16 = 0 + d.upMB[mbx].nzY16 = 0 + } + d.leftMB.nzMask = 0 + d.upMB[mbx].nzMask = 0 + d.nzDCMask = 0 + d.nzACMask = 0 + } + // Reconstruct the YCbCr data and copy it to the image. + d.reconstructMacroblock(mbx, mby) + for i, y := (mby*d.img.YStride+mbx)*16, 0; y < 16; i, y = i+d.img.YStride, y+1 { + copy(d.img.Y[i:i+16], d.ybr[ybrYY+y][ybrYX:ybrYX+16]) + } + for i, y := (mby*d.img.CStride+mbx)*8, 0; y < 8; i, y = i+d.img.CStride, y+1 { + copy(d.img.Cb[i:i+8], d.ybr[ybrBY+y][ybrBX:ybrBX+8]) + copy(d.img.Cr[i:i+8], d.ybr[ybrRY+y][ybrRX:ybrRX+8]) + } + return skip +} -- cgit v1.2.3