audio/mp3: Refactoring: Rename global variables

audio/mp3/imdct.go

@@ -51,7 +51,7 @@ var imdctWinData = [4][36]float32{
 	},
 }
 
-var cos_N12 = [6][12]float32{
+var cosN12 = [6][12]float32{
 	{
 		0.608761, 0.382683, 0.130526, -0.130526, -0.382683, -0.608761,
 		-0.793353, -0.923880, -0.991445, -0.991445, -0.923879, -0.793353,
@@ -78,7 +78,7 @@ var cos_N12 = [6][12]float32{
 	},
 }
 
-var cos_N36 = [18][36]float32{
+var cosN36 = [18][36]float32{
 	{
 		0.675590, 0.608761, 0.537300, 0.461749, 0.382683, 0.300706,
 		0.216440, 0.130526, 0.043619, -0.043619, -0.130526, -0.216440,
@@ -233,7 +233,7 @@ func imdctWin(in []float32, blockType int) []float32 {
 			for p := 0; p < N; p++ {
 				sum := float32(0.0)
 				for m := 0; m < N/2; m++ {
-					sum += in[i+3*m] * cos_N12[m][p]
+					sum += in[i+3*m] * cosN12[m][p]
 				}
 				out[6*i+p+6] += sum * imdctWinData[blockType][p]
 			}
@@ -244,7 +244,7 @@ func imdctWin(in []float32, blockType int) []float32 {
 	for p := 0; p < N; p++ {
 		sum := float32(0.0)
 		for m := 0; m < N/2; m++ {
-			sum += in[m] * cos_N36[m][p]
+			sum += in[m] * cosN36[m][p]
 		}
 		out[p] = sum * imdctWinData[blockType][p]
 	}

audio/mp3/l3.go

@@ -218,7 +218,7 @@ func (f *frame) l3Reorder(gr int, ch int) {
 }
 
 var (
-	is_ratios = [6]float32{0.000000, 0.267949, 0.577350, 1.000000, 1.732051, 3.732051}
+	isRatios = []float32{0.000000, 0.267949, 0.577350, 1.000000, 1.732051, 3.732051}
 )
 
 func (f *frame) stereoProcessIntensityLong(gr int, sfb int) {
@@ -234,8 +234,8 @@ func (f *frame) stereoProcessIntensityLong(gr int, sfb int) {
 			is_ratio_l = 1.0
 			is_ratio_r = 0.0
 		} else {
-			is_ratio_l = is_ratios[is_pos] / (1.0 + is_ratios[is_pos])
+			is_ratio_l = isRatios[is_pos] / (1.0 + isRatios[is_pos])
-			is_ratio_r = 1.0 / (1.0 + is_ratios[is_pos])
+			is_ratio_r = 1.0 / (1.0 + isRatios[is_pos])
 		}
 		/* Now decode all samples in this scale factor band */
 		for i := sfb_start; i < sfb_stop; i++ {
@@ -262,8 +262,8 @@ func (f *frame) stereoProcessIntensityShort(gr int, sfb int) {
 				is_ratio_l = 1.0
 				is_ratio_r = 0.0
 			} else {
-				is_ratio_l = is_ratios[is_pos] / (1.0 + is_ratios[is_pos])
+				is_ratio_l = isRatios[is_pos] / (1.0 + isRatios[is_pos])
-				is_ratio_r = 1.0 / (1.0 + is_ratios[is_pos])
+				is_ratio_r = 1.0 / (1.0 + isRatios[is_pos])
 			}
 			/* Now decode all samples in this scale factor band */
 			for i := sfb_start; i < sfb_stop; i++ {
@@ -344,8 +344,8 @@ func (f *frame) l3Stereo(gr int) {
 }
 
 var (
-	cs = [8]float32{0.857493, 0.881742, 0.949629, 0.983315, 0.995518, 0.999161, 0.999899, 0.999993}
+	cs = []float32{0.857493, 0.881742, 0.949629, 0.983315, 0.995518, 0.999161, 0.999899, 0.999993}
-	ca = [8]float32{-0.514496, -0.471732, -0.313377, -0.181913, -0.094574, -0.040966, -0.014199, -0.003700}
+	ca = []float32{-0.514496, -0.471732, -0.313377, -0.181913, -0.094574, -0.040966, -0.014199, -0.003700}
 )
 
 func (f *frame) l3Antialias(gr int, ch int) {
@@ -406,18 +406,18 @@ func (f *frame) l3FrequencyInversion(gr int, ch int) {
 	}
 }
 
-var g_synth_n_win = [64][32]float32{}
+var synthNWin = [64][32]float32{}
 
 func init() {
 	for i := 0; i < 64; i++ {
 		for j := 0; j < 32; j++ {
-			g_synth_n_win[i][j] =
+			synthNWin[i][j] =
 				float32(math.Cos(float64((16+i)*(2*j+1)) * (math.Pi / 64.0)))
 		}
 	}
 }
 
-var g_synth_dtbl = [512]float32{
+var synthDtbl = [512]float32{
 	0.000000000, -0.000015259, -0.000015259, -0.000015259,
 	-0.000015259, -0.000015259, -0.000015259, -0.000030518,
 	-0.000030518, -0.000030518, -0.000030518, -0.000045776,
@@ -564,7 +564,7 @@ func (f *frame) l3SubbandSynthesis(gr int, ch int, out []uint8) {
 		for i := 0; i < 64; i++ { /* Matrix multiply input with n_win[][] matrix */
 			sum := float32(0)
 			for j := 0; j < 32; j++ {
-				sum += g_synth_n_win[i][j] * s_vec[j]
+				sum += synthNWin[i][j] * s_vec[j]
 			}
 			f.v_vec[ch][i] = sum
 		}
@@ -574,8 +574,8 @@ func (f *frame) l3SubbandSynthesis(gr int, ch int, out []uint8) {
 				u_vec[(i<<6)+j+32] = f.v_vec[ch][(i<<7)+j+96]
 			}
 		}
-		for i := 0; i < 512; i++ { /* Window by u_vec[i] with g_synth_dtbl[i] */
+		for i := 0; i < 512; i++ { /* Window by u_vec[i] with synthDtbl[i] */
-			u_vec[i] *= g_synth_dtbl[i]
+			u_vec[i] *= synthDtbl[i]
 		}
 		for i := 0; i < 32; i++ { /* Calc 32 samples,store in outdata vector */
 			sum := float32(0)

audio/mp3/maindata.go

@@ -29,11 +29,7 @@ var mpeg1_scalefac_sizes = [16][2]int{
 func (f *frame) readMainL3() error {
 	nch := f.numberOfChannels()
 	// Calculate header audio data size
-	framesize := (144*
+	framesize := f.size()
-		g_mpeg1_bitrates[f.header.layer][f.header.bitrate_index])/
-		g_sampling_frequency[f.header.sampling_frequency] +
-		f.header.padding_bit
-
 	if framesize > 2000 {
 		return fmt.Errorf("mp3: framesize = %d", framesize)
 	}

audio/mp3/sideinfo.go

@@ -21,7 +21,7 @@ import (
 	"io"
 )
 
-var g_mpeg1_bitrates = map[mpeg1Layer][15]int{
+var mpeg1Bitrates = map[mpeg1Layer][15]int{
 	mpeg1Layer1: {
 		0, 32000, 64000, 96000, 128000, 160000, 192000, 224000,
 		256000, 288000, 320000, 352000, 384000, 416000, 448000,
@@ -36,15 +36,18 @@ var g_mpeg1_bitrates = map[mpeg1Layer][15]int{
 	},
 }
 
-var g_sampling_frequency = [3]int{44100, 48000, 32000}
+var samplingFrequency = [3]int{44100, 48000, 32000}
+
+func (f *frame) size() int {
+	return (144*mpeg1Bitrates[f.header.layer][f.header.bitrate_index])/
+		samplingFrequency[f.header.sampling_frequency] +
+		int(f.header.padding_bit)
+}
 
 func (f *frame) readAudioL3() error {
 	nch := f.numberOfChannels()
 	/* Calculate header audio data size */
-	framesize := (144*
+	framesize := f.size()
-		g_mpeg1_bitrates[f.header.layer][f.header.bitrate_index])/
-		g_sampling_frequency[f.header.sampling_frequency] +
-		int(f.header.padding_bit)
 	if framesize > 2000 {
 		return fmt.Errorf("mp3: framesize = %d\n", framesize)
 	}