codec/h264/h264dec: using const string instead of CSV file to hold table 9-5. Also made some other minor improvements

codec/h264/h264dec/cavlc.go

@@ -29,32 +29,13 @@ import (
 	"encoding/csv"
 	"errors"
 	"fmt"
-	"os"
 	"strconv"
+	"strings"
 
 	"bitbucket.org/ausocean/av/codec/h264/h264dec/bits"
 )
 
-// Initialize the CAVLC coeff_token mapping table.
+// TODO: find where these are defined in the specifications.
-func init() {
-	const file = "coefftokenmap.csv"
-	f, err := os.Open(file)
-	if err != nil {
-		panic(fmt.Sprintf("could not open coefftokenmap.csv file, failed with error: %v", err))
-	}
-	defer f.Close()
-
-	lines, err := csv.NewReader(f).ReadAll()
-	if err != nil {
-		panic(fmt.Sprintf("could not read lines from coeftokenmap.csv file, failed with error: %v", err))
-	}
-
-	coeffTokenMaps, err = formCoeffTokenMap(lines)
-	if err != nil {
-		panic(fmt.Sprintf("could not form coeff_token map, failed with err: %v", err))
-	}
-}
-
 const (
 	chromaDCLevel = iota
 	intra16x16DCLevel
@@ -68,6 +49,93 @@ const (
 	crLevel4x4
 )
 
+// Initialize the CAVLC coeff_token mapping table.
+func init() {
+	lines, err := csv.NewReader(strings.NewReader(coeffTokenTable)).ReadAll()
+	if err != nil {
+		panic(fmt.Sprintf("could not read lines from coeftokenmap.csv file, failed with error: %v", err))
+	}
+
+	coeffTokenMaps, err = formCoeffTokenMap(lines)
+	if err != nil {
+		panic(fmt.Sprintf("could not form coeff_token map, failed with err: %v", err))
+	}
+}
+
+// tokenMap maps coeff_token to values of TrailingOnes(coeff_token) and
+// TotalCoeff(coeff_token) given as tokenMap[ number of leading zeros in
+// coeff_token][ coeff_token val ][ 0 for trailing ones and 1 for totalCoef ]
+type tokenMap map[int]map[int][2]int
+
+// The number of columns in the coeffTokenMap defined below. This is
+// representative of the number of defined nC ranges in table 9-5.
+const nColumns = 6
+
+// coeffTokenMaps holds a representation of table 9-5 from the specifications, and
+// is indexed as follows, coeffToken[ nC group ][ number of coeff_token leading
+// zeros ][ value of coeff_token ][ 0 for TrailingOnes(coeff_token) and 1 for
+// TotalCoef(coeff_token) ].
+var coeffTokenMaps [nColumns]tokenMap
+
+// formCoeffTokenMap populates the global [nColumns]tokenMap coeffTokenMaps
+// representation of table 9-5 in the specifications using the coeffTokenTable
+// const string defined in cavlctab.go.
+func formCoeffTokenMap(lines [][]string) ([nColumns]tokenMap, error) {
+	var maps [nColumns]tokenMap
+
+	for i := range maps {
+		maps[i] = make(tokenMap)
+	}
+
+	for _, line := range lines {
+		trailingOnes, err := strconv.Atoi(line[0])
+		if err != nil {
+			return maps, fmt.Errorf("could not convert trailingOnes string to int, failed with error: %v", err)
+		}
+
+		totalCoeff, err := strconv.Atoi(line[1])
+		if err != nil {
+			return maps, fmt.Errorf("could not convert totalCoeff string to int, failed with error: %v", err)
+		}
+
+		// For each column in this row, therefore each nC category, load the
+		// coeff_token leading zeros and value into the map.
+		for j, v := range line[2:] {
+			if v[0] == '-' {
+				continue
+			}
+
+			// Count the leading zeros.
+			var nZeros int
+			for _, c := range v {
+				if c == ' ' {
+					continue
+				}
+
+				if c == '0' {
+					nZeros++
+					continue
+				}
+				break
+			}
+
+			// This will be the value of the coeff_token (without leading zeros).
+			val, err := binToInt(v[nZeros:])
+			if err != nil {
+				return maps, fmt.Errorf("could not get value of remaining binary, failed with error: %v", err)
+			}
+
+			// Add the TrailingOnes(coeff_token) and TotalCoeff(coeff_token) values
+			// into the map for the coeff_token leading zeros and value.
+			if maps[j][nZeros] == nil {
+				maps[j][nZeros] = make(map[int][2]int)
+			}
+			maps[j][nZeros][val] = [2]int{trailingOnes, totalCoeff}
+		}
+	}
+	return maps, nil
+}
+
 // TODO: put this somewhere more appropriate once context is understood.
 type block struct {
 	usingInterMbPredMode bool
@@ -243,80 +311,6 @@ func available(b block) bool {
 	return true
 }
 
-// The number of columns in the coeffTokenMap defined below. This is
-// representative of the number of defined nC ranges defined in table 9-5.
-const nColumns = 6
-
-// coeffMapping maps values of coeff_token to values of TrailingOnes(coeff_token)
-// and TotalCoeff(coeff_token) given as map[ coeff_token val ][ 0 for trailing ones
-// and 1 for totalCoef ]
-type tokenMap map[int]map[int][2]int
-
-// coeffTokenMap will a representation of table 9-5 from the specifications, and
-// is indexed as follows, coeffToken[ nC group ][ number of coeff_token leading
-// zeros ][ value of coeff_token ][ 0 for TrailingOnes(coeff_token) and 1 for
-// TotalCoef(coeff_token) ].
-var coeffTokenMaps [nColumns]tokenMap
-
-// formCoeffTokenMap populates the global [nColumns]map[int]map[int][2]int,
-// coeffTokenMap representation of table 9-5 from the specifications using lines
-// read from a corresponding CSV file coefftokenmap.csv.
-func formCoeffTokenMap(lines [][]string) ([nColumns]tokenMap, error) {
-	var maps [nColumns]tokenMap
-
-	for i := range maps {
-		maps[i] = make(tokenMap)
-	}
-
-	for _, line := range lines {
-		trailingOnes, err := strconv.Atoi(line[0])
-		if err != nil {
-			return maps, fmt.Errorf("could not convert trailingOnes string to int, failed with error: %v", err)
-		}
-
-		totalCoeff, err := strconv.Atoi(line[1])
-		if err != nil {
-			return maps, fmt.Errorf("could not convert totalCoeff string to int, failed with error: %v", err)
-		}
-
-		// For each column in this row, therefore each nC category, load the
-		// coeff_token leading zeros and value into the map.
-		for j, v := range line[2:] {
-			if v[0] == '-' {
-				continue
-			}
-
-			// Count the leading zeros.
-			var nZeros int
-			for _, c := range v {
-				if c == ' ' {
-					continue
-				}
-
-				if c == '0' {
-					nZeros++
-					continue
-				}
-				break
-			}
-
-			// This will be the value of the coeff_token (without leading zeros).
-			val, err := binToInt(v[nZeros:])
-			if err != nil {
-				return maps, fmt.Errorf("could not get value of remaining binary, failed with error: %v", err)
-			}
-
-			// Add the TrailingOnes(coeff_token) and TotalCoeff(coeff_token) values
-			// into the map for the coeff_token leading zeros and value.
-			if maps[j][nZeros] == nil {
-				maps[j][nZeros] = make(map[int][2]int)
-			}
-			maps[j][nZeros][val] = [2]int{trailingOnes, totalCoeff}
-		}
-	}
-	return maps, nil
-}
-
 // parseLevelPrefix parses the level_prefix variable as specified by the process
 // outlined in section 9.2.2.1 in the specifications.
 func parseLevelPrefix(br *bits.BitReader) (int, error) {

codec/h264/h264dec/cavlc_test.go

@@ -35,14 +35,14 @@ import (
 func TestFormCoeffTokenMap(t *testing.T) {
 	tests := []struct {
 		in   [][]string
-		want [nColumns]map[int]map[int][2]int
+		want [nColumns]tokenMap
 	}{
 		{
 			in: [][]string{
 				{"0", "0", "1", "11", "1111", "0000 11", "01", "1"},
 				{"0", "1", "0001 01", "0010 11", "0011 11", "0000 00", "0001 11", "0001 111"},
 			},
-			want: [nColumns]map[int]map[int][2]int{
+			want: [nColumns]tokenMap{
 				0: {
 					0: {1: {0, 0}},
 					3: {5: {0, 1}},
@@ -74,7 +74,7 @@ func TestFormCoeffTokenMap(t *testing.T) {
 				{"0", "0", "1", "11", "1111", "0000 11", "01", "1"},
 				{"0", "1", "0001 01", "0010 11", "0011 11", "-", "0001 11", "0001 111"},
 			},
-			want: [nColumns]map[int]map[int][2]int{
+			want: [nColumns]tokenMap{
 				0: {
 					0: {1: {0, 0}},
 					3: {5: {0, 1}},

codec/h264/h264dec/cavlctab.go

@@ -1,4 +1,6 @@
-0,0,1,11,1111,0000 11,01,1
+package h264dec
+
+const coeffTokenTable = `0,0,1,11,1111,0000 11,01,1
 0,1,0001 01,0010 11,0011 11,0000 00,0001 11,0001 111
 1,1,01,10,1110,0000 01,1,01
 0,2,0000 0111,0001 11,0010 11,0001 00,0001 00,0001 110
@@ -59,4 +61,4 @@
 0,16,0000 0000 0000 0100,0000 0000 0001 11,0000 0000 01,1111 00,-,-
 1,16,0000 0000 0000 0110,0000 0000 0001 10,0000 0001 00,1111 01,-,-
 2,16,0000 0000 0000 0101,0000 0000 0001 01,0000 0000 11,1111 10,-,-
-3,16,0000 0000 0000 1000,0000 0000 0001 00,0000 0000 10,1111 11,-,-
+3,16,0000 0000 0000 1000,0000 0000 0001 00,0000 0000 10,1111 11,-,-`