Extra param support

wave/reader.go

@@ -34,6 +34,7 @@ var (
 	maxValues = map[int]int{
 		8:  math.MaxInt8,
 		16: math.MaxInt16,
+		24: math.MaxInt32 >> 8,
 		32: math.MaxInt32,
 		64: math.MaxInt64,
 	}
@@ -143,6 +144,18 @@ func readData(b []byte, wfmt WaveFmt) WaveData {
 
 	start := 36 + wfmt.ExtraParamSize
 	subchunk2ID := b[start : start+4]
+
+	if !bytes.Equal(subchunk2ID, []byte{0x64, 0x61, 0x74, 0x61}) {
+		// some files put "unknown" chunks between FMT and DATA, we can manually
+		// seek at this point to see if "data" does appear somewhere..
+		for i := 0; i < len(b)-4; i++ {
+			if bytes.Equal(b[i:i+4], []byte{0x64, 0x61, 0x74, 0x61}) {
+				subchunk2ID = b[i : i+4]
+				break
+			}
+		}
+
+	}
 	wd.Subchunk2ID = subchunk2ID
 
 	subsize := bits32ToInt(b[start+4 : start+8])
@@ -233,6 +246,7 @@ func readFmt(b []byte) WaveFmt {
 	if subchunksize != 16 {
 		// only for compressed files (non-PCM)
 		extraSize := bits16ToInt(b[36:38])
+		//wfmt.ExtraParamSize = extraSize
 		wfmt.ExtraParamSize = extraSize
 		wfmt.ExtraParams = b[38 : 38+extraSize]
 	}

wave/reader_test.go

@@ -1,6 +1,7 @@
 package wave
 
 import (
+	"bytes"
 	"runtime/debug"
 	"testing"
 )
@@ -95,7 +96,7 @@ func TestScaleFrames(t *testing.T) {
 func TestJunkChunkFile(t *testing.T) {
 	defer func() {
 		if r := recover(); r != nil {
-			t.Fatalf("Should not have panic'd reading JUNK files\n%v", string(debug.Stack()))
+			t.Fatalf("Should not have panic'd reading JUNK files\n%v\n%v", string(debug.Stack()), r)
 		}
 	}()
 
@@ -113,4 +114,12 @@ func TestJunkChunkFile(t *testing.T) {
 	if wav.NumChannels != 2 {
 		t.Fatalf("Expected 2 channels, got: %v", wav.NumChannels)
 	}
+
+	if !bytes.Equal(wav.WaveFmt.Subchunk1ID, []byte{0x66, 0x6d, 0x74, 0x20}) {
+		t.Fatalf("Expected Subchunk1ID to contain 'fmt'")
+	}
+
+	if !bytes.Equal(wav.WaveData.Subchunk2ID, []byte{0x64, 0x61, 0x74, 0x61}) {
+		t.Fatalf("Expected Subchunk2ID to contain 'data', but got %x", wav.WaveData.Subchunk2ID)
+	}
 }

wave/writer.go

@@ -22,6 +22,7 @@ var (
 	// intsToBytesFm to map X-bit int to byte functions
 	intsToBytesFm = map[int]intsToBytesFunc{
 		16: int16ToBytes,
+		24: int24ToBytes,
 		32: int32ToBytes,
 	}
 )
@@ -71,6 +72,14 @@ func int16ToBytes(i int) []byte {
 	return b
 }
 
+func int24ToBytes(i int) []byte {
+	b := make([]byte, 3)
+	b[0] = byte(i & 0xff)
+	b[1] = byte((i >> 8) & 0xff)
+	b[2] = byte((i >> 16) & 0xff)
+	return b
+}
+
 func int32ToBytes(i int) []byte {
 	b := make([]byte, 4)
 	in := uint32(i)
@@ -143,6 +152,7 @@ func fmtToBytes(wfmt WaveFmt) []byte {
 	br := int32ToBytes(wfmt.ByteRate)
 	blockalign := int16ToBytes(wfmt.BlockAlign)
 	bitsPerSample := int16ToBytes(wfmt.BitsPerSample)
+	extraParamSize := int16ToBytes(wfmt.ExtraParamSize)
 
 	b = append(b, wfmt.Subchunk1ID...)
 	b = append(b, subchunksize...)
@@ -153,6 +163,10 @@ func fmtToBytes(wfmt WaveFmt) []byte {
 	b = append(b, blockalign...)
 	b = append(b, bitsPerSample...)
 
+	// extra params if present
+	b = append(b, extraParamSize...)
+	b = append(b, wfmt.ExtraParams...)
+
 	return b
 }
 

wave/writer_test.go

@@ -56,3 +56,16 @@ func TestWriteWave(t *testing.T) {
 		t.Fatalf("Should be able to write file: %v", err)
 	}
 }
+
+// TestWriteWave reads wave file and writes it, ensuring nothing is different between the two
+func TestWrite24BitWave(t *testing.T) {
+	goldenfile := "./golden/24bit.wav"
+	wav, err := ReadWaveFile(goldenfile)
+	if err != nil {
+		t.Fatalf("Should be able to read 24-bit wave file: %v", err)
+	}
+
+	if err := WriteFrames(wav.Frames, wav.WaveFmt, "output24.wav"); err != nil {
+		t.Fatalf("Should be able to write file: %v", err)
+	}
+}