1 files changed, 177 insertions, 0 deletions
diff --git a/wav/wav.go b/wav/wav.go
new file mode 100644
index 0000000..b82ec16
--- /dev/null
+++ b/wav/wav.go
@@ -0,0 +1,177 @@
+package wav
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+)
+
+type WavFile struct {
+	Header Header
+	Format FormatChunk
+	Data   DataChunk
+}
+
+type Header struct {
+	GroupID    [4]uint8
+	FileLength uint32
+	RiffType   [4]uint8
+}
+
+type FormatChunk struct {
+	GroupID    [4]uint8
+	ChunkSize  uint32
+	FormatTag  uint16
+	Channels   uint16
+	SampleRate uint32
+	ByteRate   uint32
+	Alignment  uint16
+	BitDensity uint32
+}
+
+type DataChunk struct {
+	GroupID   [4]uint8
+	ChunkSize uint32
+	Samples   io.Reader
+}
+
+func Load(filename string) (*WavFile, error) {
+	file, err := os.Open(filename)
+
+	if err != nil {
+		return nil, err
+	}
+
+	load16 := func(b []byte) (uint16, error) {
+		var out uint16
+		err := binary.Read(bytes.NewBuffer(b), binary.LittleEndian, &out)
+		return out, err
+	}
+
+	load32 := func(b []byte) (uint32, error) {
+		var out uint32
+		err := binary.Read(bytes.NewBuffer(b), binary.LittleEndian, &out)
+		return out, err
+
+	}
+
+	b, err := ioutil.ReadAll(io.LimitReader(file, 40))
+	if err != nil {
+		return nil, err
+	}
+
+	h := Header{}
+	h.FileLength, err = load32(b[4:36])
+	if err != nil {
+		return nil, err
+	}
+	h.FileLength -= 8 // subtract RIFF/WAVE markers
+
+	for i := 0; i < 4; i++ {
+		h.GroupID[i] = b[i]
+		h.RiffType[i] = b[i+36]
+	}
+
+	fmt.Println(h)
+	fmt.Println(string(h.RiffType[:]))
+
+	if string(h.GroupID[:]) != "RIFF" { // || string(h.RiffType[:]) != "WAVE" {
+		return nil, fmt.Errorf("invalid header!")
+	}
+
+	f := FormatChunk{}
+
+	file.Seek(40, io.SeekStart)
+	b, err = ioutil.ReadAll(io.LimitReader(file, 36))
+	if err != nil {
+		return nil, err
+	}
+
+	for i := 0; i < 4; i++ {
+		f.GroupID[i] = b[i]
+	}
+
+	f.ChunkSize, err = load32(b[4:36])
+	if err != nil {
+		return nil, err
+	}
+
+	file.Seek(76, io.SeekStart)
+	b, err = ioutil.ReadAll(io.LimitReader(file, int64(f.ChunkSize)))
+	if err != nil {
+		return nil, err
+	}
+
+	f.FormatTag, err = load16(b[36:52])
+	if err != nil {
+		return nil, err
+	}
+
+	f.Channels, err = load16(b[52:68])
+	if err != nil {
+		return nil, err
+	}
+
+	f.SampleRate, err = load32(b[68:100])
+	if err != nil {
+		return nil, err
+	}
+
+	f.ByteRate, err = load32(b[100:132])
+	if err != nil {
+		return nil, err
+	}
+
+	f.Alignment, err = load16(b[132:148])
+	if err != nil {
+		return nil, err
+	}
+
+	f.BitDensity, err = load32(b[138:180])
+	if err != nil {
+		return nil, err
+	}
+
+	if string(f.GroupID[:]) != "fmt " ||
+		f.FormatTag != 1 ||
+		f.Alignment != uint16((uint32(f.Channels)*f.BitDensity/8)&0xff) {
+		return nil, fmt.Errorf("invalid format block!")
+	}
+
+	if f.BitDensity != 16 || f.Channels != 2 || f.SampleRate != 44100 {
+		return nil, fmt.Errorf("wrong pcm format!")
+	}
+
+	d := DataChunk{}
+
+	file.Seek(220, io.SeekStart)
+	b, err = ioutil.ReadAll(io.LimitReader(file, 36))
+	if err != nil {
+		return nil, err
+	}
+
+	for i := 0; i < 4; i++ {
+		d.GroupID[i] = b[i]
+	}
+
+	d.ChunkSize, err = load32(b[4:])
+	if err != nil {
+		return nil, err
+	}
+
+	if string(f.GroupID[:]) != "fmt " {
+		return nil, fmt.Errorf("invalid data block!")
+	}
+
+	file.Seek(256, io.SeekStart)
+	d.Samples = io.LimitReader(file, int64(d.ChunkSize))
+
+	return &WavFile{
+		Header: h,
+		Format: f,
+		Data:   d,
+	}, nil
+}