golang-image/vp8/pred.go

// 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 parsing the predictor modes, as specified in chapter
// 11.

func (d *Decoder) parsePredModeY16(mbx int) {
	var p uint8
	if !d.fp.readBit(156) {
		if !d.fp.readBit(163) {
			p = predDC
		} else {
			p = predVE
		}
	} else if !d.fp.readBit(128) {
		p = predHE
	} else {
		p = predTM
	}
	for i := 0; i < 4; i++ {
		d.upMB[mbx].pred[i] = p
		d.leftMB.pred[i] = p
	}
	d.predY16 = p
}

func (d *Decoder) parsePredModeC8() {
	if !d.fp.readBit(142) {
		d.predC8 = predDC
	} else if !d.fp.readBit(114) {
		d.predC8 = predVE
	} else if !d.fp.readBit(183) {
		d.predC8 = predHE
	} else {
		d.predC8 = predTM
	}
}

func (d *Decoder) parsePredModeY4(mbx int) {
	for j := 0; j < 4; j++ {
		p := d.leftMB.pred[j]
		for i := 0; i < 4; i++ {
			prob := &predProb[d.upMB[mbx].pred[i]][p]
			if !d.fp.readBit(prob[0]) {
				p = predDC
			} else if !d.fp.readBit(prob[1]) {
				p = predTM
			} else if !d.fp.readBit(prob[2]) {
				p = predVE
			} else if !d.fp.readBit(prob[3]) {
				if !d.fp.readBit(prob[4]) {
					p = predHE
				} else if !d.fp.readBit(prob[5]) {
					p = predRD
				} else {
					p = predVR
				}
			} else if !d.fp.readBit(prob[6]) {
				p = predLD
			} else if !d.fp.readBit(prob[7]) {
				p = predVL
			} else if !d.fp.readBit(prob[8]) {
				p = predHD
			} else {
				p = predHU
			}
			d.predY4[j][i] = p
			d.upMB[mbx].pred[i] = p
		}
		d.leftMB.pred[j] = p
	}
}

// predProb are the probabilities to decode a 4x4 region's predictor mode given
// the predictor modes of the regions above and left of it.
// These values are specified in section 11.5.
var predProb = [nPred][nPred][9]uint8{
	{
		{231, 120, 48, 89, 115, 113, 120, 152, 112},
		{152, 179, 64, 126, 170, 118, 46, 70, 95},
		{175, 69, 143, 80, 85, 82, 72, 155, 103},
		{56, 58, 10, 171, 218, 189, 17, 13, 152},
		{114, 26, 17, 163, 44, 195, 21, 10, 173},
		{121, 24, 80, 195, 26, 62, 44, 64, 85},
		{144, 71, 10, 38, 171, 213, 144, 34, 26},
		{170, 46, 55, 19, 136, 160, 33, 206, 71},
		{63, 20, 8, 114, 114, 208, 12, 9, 226},
		{81, 40, 11, 96, 182, 84, 29, 16, 36},
	},
	{
		{134, 183, 89, 137, 98, 101, 106, 165, 148},
		{72, 187, 100, 130, 157, 111, 32, 75, 80},
		{66, 102, 167, 99, 74, 62, 40, 234, 128},
		{41, 53, 9, 178, 241, 141, 26, 8, 107},
		{74, 43, 26, 146, 73, 166, 49, 23, 157},
		{65, 38, 105, 160, 51, 52, 31, 115, 128},
		{104, 79, 12, 27, 217, 255, 87, 17, 7},
		{87, 68, 71, 44, 114, 51, 15, 186, 23},
		{47, 41, 14, 110, 182, 183, 21, 17, 194},
		{66, 45, 25, 102, 197, 189, 23, 18, 22},
	},
	{
		{88, 88, 147, 150, 42, 46, 45, 196, 205},
		{43, 97, 183, 117, 85, 38, 35, 179, 61},
		{39, 53, 200, 87, 26, 21, 43, 232, 171},
		{56, 34, 51, 104, 114, 102, 29, 93, 77},
		{39, 28, 85, 171, 58, 165, 90, 98, 64},
		{34, 22, 116, 206, 23, 34, 43, 166, 73},
		{107, 54, 32, 26, 51, 1, 81, 43, 31},
		{68, 25, 106, 22, 64, 171, 36, 225, 114},
		{34, 19, 21, 102, 132, 188, 16, 76, 124},
		{62, 18, 78, 95, 85, 57, 50, 48, 51},
	},
	{
		{193, 101, 35, 159, 215, 111, 89, 46, 111},
		{60, 148, 31, 172, 219, 228, 21, 18, 111},
		{112, 113, 77, 85, 179, 255, 38, 120, 114},
		{40, 42, 1, 196, 245, 209, 10, 25, 109},
		{88, 43, 29, 140, 166, 213, 37, 43, 154},
		{61, 63, 30, 155, 67, 45, 68, 1, 209},
		{100, 80, 8, 43, 154, 1, 51, 26, 71},
		{142, 78, 78, 16, 255, 128, 34, 197, 171},
		{41, 40, 5, 102, 211, 183, 4, 1, 221},
		{51, 50, 17, 168, 209, 192, 23, 25, 82},
	},
	{
		{138, 31, 36, 171, 27, 166, 38, 44, 229},
		{67, 87, 58, 169, 82, 115, 26, 59, 179},
		{63, 59, 90, 180, 59, 166, 93, 73, 154},
		{40, 40, 21, 116, 143, 209, 34, 39, 175},
		{47, 15, 16, 183, 34, 223, 49, 45, 183},
		{46, 17, 33, 183, 6, 98, 15, 32, 183},
		{57, 46, 22, 24, 128, 1, 54, 17, 37},
		{65, 32, 73, 115, 28, 128, 23, 128, 205},
		{40, 3, 9, 115, 51, 192, 18, 6, 223},
		{87, 37, 9, 115, 59, 77, 64, 21, 47},
	},
	{
		{104, 55, 44, 218, 9, 54, 53, 130, 226},
		{64, 90, 70, 205, 40, 41, 23, 26, 57},
		{54, 57, 112, 184, 5, 41, 38, 166, 213},
		{30, 34, 26, 133, 152, 116, 10, 32, 134},
		{39, 19, 53, 221, 26, 114, 32, 73, 255},
		{31, 9, 65, 234, 2, 15, 1, 118, 73},
		{75, 32, 12, 51, 192, 255, 160, 43, 51},
		{88, 31, 35, 67, 102, 85, 55, 186, 85},
		{56, 21, 23, 111, 59, 205, 45, 37, 192},
		{55, 38, 70, 124, 73, 102, 1, 34, 98},
	},
	{
		{125, 98, 42, 88, 104, 85, 117, 175, 82},
		{95, 84, 53, 89, 128, 100, 113, 101, 45},
		{75, 79, 123, 47, 51, 128, 81, 171, 1},
		{57, 17, 5, 71, 102, 57, 53, 41, 49},
		{38, 33, 13, 121, 57, 73, 26, 1, 85},
		{41, 10, 67, 138, 77, 110, 90, 47, 114},
		{115, 21, 2, 10, 102, 255, 166, 23, 6},
		{101, 29, 16, 10, 85, 128, 101, 196, 26},
		{57, 18, 10, 102, 102, 213, 34, 20, 43},
		{117, 20, 15, 36, 163, 128, 68, 1, 26},
	},
	{
		{102, 61, 71, 37, 34, 53, 31, 243, 192},
		{69, 60, 71, 38, 73, 119, 28, 222, 37},
		{68, 45, 128, 34, 1, 47, 11, 245, 171},
		{62, 17, 19, 70, 146, 85, 55, 62, 70},
		{37, 43, 37, 154, 100, 163, 85, 160, 1},
		{63, 9, 92, 136, 28, 64, 32, 201, 85},
		{75, 15, 9, 9, 64, 255, 184, 119, 16},
		{86, 6, 28, 5, 64, 255, 25, 248, 1},
		{56, 8, 17, 132, 137, 255, 55, 116, 128},
		{58, 15, 20, 82, 135, 57, 26, 121, 40},
	},
	{
		{164, 50, 31, 137, 154, 133, 25, 35, 218},
		{51, 103, 44, 131, 131, 123, 31, 6, 158},
		{86, 40, 64, 135, 148, 224, 45, 183, 128},
		{22, 26, 17, 131, 240, 154, 14, 1, 209},
		{45, 16, 21, 91, 64, 222, 7, 1, 197},
		{56, 21, 39, 155, 60, 138, 23, 102, 213},
		{83, 12, 13, 54, 192, 255, 68, 47, 28},
		{85, 26, 85, 85, 128, 128, 32, 146, 171},
		{18, 11, 7, 63, 144, 171, 4, 4, 246},
		{35, 27, 10, 146, 174, 171, 12, 26, 128},
	},
	{
		{190, 80, 35, 99, 180, 80, 126, 54, 45},
		{85, 126, 47, 87, 176, 51, 41, 20, 32},
		{101, 75, 128, 139, 118, 146, 116, 128, 85},
		{56, 41, 15, 176, 236, 85, 37, 9, 62},
		{71, 30, 17, 119, 118, 255, 17, 18, 138},
		{101, 38, 60, 138, 55, 70, 43, 26, 142},
		{146, 36, 19, 30, 171, 255, 97, 27, 20},
		{138, 45, 61, 62, 219, 1, 81, 188, 64},
		{32, 41, 20, 117, 151, 142, 20, 21, 163},
		{112, 19, 12, 61, 195, 128, 48, 4, 24},
	},
}