wav.go

package wav

import (
	"bytes"
	"encoding/binary"
)

type Head struct {
	ChunkID   [4]byte //内容为"RIFF"
	ChunkSize uint32  //wav文件的字节数, 不包含ChunkID和ChunkSize这8个字节）
	Format    [4]byte //内容为WAVE
}

type Fmt struct {
	Subchunk1ID   [4]byte //内容为"fmt "
	Subchunk1Size uint32  // Fmt所占字节数，为16
	AudioFormat   uint16  //存储音频的编码格式，pcm为1
	NumChannels   uint16  //通道数, 单通道为1,双通道为2
	SampleRate    uint32  //采样率，如8k, 44.1k等
	ByteRate      uint32  //每秒存储的byte数，其值=SampleRate * NumChannels * BitsPerSample/8
	BlockAlign    uint16  //块对齐大小，其值=NumChannels * BitsPerSample/8
	BitsPerSample uint16  //每个采样点的bit数，一般为8,16,32等。
}

type Data struct {
	Subchunk2ID   [4]byte //内容为"data"
	Subchunk2Size uint32  //内容为接下来的正式的数据部分的字节数，其值=NumSamples * NumChannels * BitsPerSample/8
}

type WavHead struct {
	Head
	Fmt
	Data
}

func New(numChannels uint16, sampleRate uint32, bitsPerSample uint16, wavLen uint32) *WavHead {
	head := &WavHead{
		Head: Head{
			//ChunkID:   []byte("RIFF"),
			ChunkSize: uint32(36 + wavLen),
			//Format:    []byte("WAVE"),
		},
		Fmt: Fmt{
			//Subchunk1ID:   []byte("fmt "),
			Subchunk1Size: 16,
			AudioFormat:   1,
			NumChannels:   numChannels,
			SampleRate:    sampleRate,
			ByteRate:      sampleRate * uint32(numChannels) * uint32(bitsPerSample) / 8,
			BlockAlign:    numChannels * bitsPerSample / 8,
			BitsPerSample: bitsPerSample,
		},
		Data: Data{
			//Subchunk2ID:   []byte("data"),
			Subchunk2Size: uint32(wavLen),
		},
	}

	copy(head.ChunkID[:], "RIFF")
	copy(head.Format[:], "WAVE")
	copy(head.Subchunk1ID[:], "fmt ")
	copy(head.Subchunk2ID[:], "data")
	return head
}

func (wh *WavHead) Marshal() ([]byte, error) {

	buf := &bytes.Buffer{}

	err := binary.Write(buf, binary.LittleEndian, *wh)

	if err != nil {
		return nil, err
	}

	return buf.Bytes(), nil
}