// Decode decodes Ogg/Vorbis data to playable stream.
//
// Sample rate is automatically adjusted to fit with the audio context.
func Decode(context *audio.Context, src audio.ReadSeekCloser) (*Stream, error) {
decoded, channelNum, sampleRate, err := decode(src)
if err != nil {
return nil, err
}
if channelNum != 1 && channelNum != 2 {
return nil, fmt.Errorf("vorbis: number of channels must be 1 or 2 but was %d", channelNum)
}
var s audio.ReadSeekCloser = decoded
size := decoded.Size()
if channelNum == 1 {
s = convert.NewStereo16(s, true, false)
size *= 2
}
if sampleRate != context.SampleRate() {
s = convert.NewResampling(s, size, sampleRate, context.SampleRate())
size = size * int64(context.SampleRate()) / int64(sampleRate)
}
return &Stream{s, size}, nil
}
// Decode decodes WAV (RIFF) data to playable stream.
//
// The format must be 1 or 2 channels, 8bit or 16bit little endian PCM.
// The format is converted into 2 channels and 16bit.
//
// Sample rate is automatically adjusted to fit with the audio context.
func Decode(context *audio.Context, src audio.ReadSeekCloser) (*Stream, error) {
buf := make([]byte, 12)
n, err := io.ReadFull(src, buf)
if n != len(buf) {
return nil, fmt.Errorf("wav: invalid header")
}
if err != nil {
return nil, err
}
if !bytes.Equal(buf[0:4], []byte("RIFF")) {
return nil, fmt.Errorf("wav: invalid header: 'RIFF' not found")
}
if !bytes.Equal(buf[8:12], []byte("WAVE")) {
return nil, fmt.Errorf("wav: invalid header: 'WAVE' not found")
}
// Read chunks
dataSize := int64(0)
headerSize := int64(0)
sampleRateFrom := 0
sampleRateTo := 0
mono := false
bitsPerSample := 0
chunks:
for {
buf := make([]byte, 8)
n, err := io.ReadFull(src, buf)
if n != len(buf) {
return nil, fmt.Errorf("wav: invalid header")
}
if err != nil {
return nil, err
}
headerSize += 8
size := int64(buf[4]) | int64(buf[5])<<8 | int64(buf[6])<<16 | int64(buf[7])<<24
switch {
case bytes.Equal(buf[0:4], []byte("fmt ")):
// Size of 'fmt' header is usually 16, but can be more than 16.
if size < 16 {
return nil, fmt.Errorf("wav: invalid header: maybe non-PCM file?")
}
buf := make([]byte, size)
n, err := io.ReadFull(src, buf)
if n != len(buf) {
return nil, fmt.Errorf("wav: invalid header")
}
if err != nil {
return nil, err
}
format := int(buf[0]) | int(buf[1])<<8
if format != 1 {
return nil, fmt.Errorf("wav: format must be linear PCM")
}
channelNum := int(buf[2]) | int(buf[3])<<8
switch channelNum {
case 1:
mono = true
case 2:
mono = false
default:
return nil, fmt.Errorf("wav: channel num must be 1 or 2 but was %d", channelNum)
}
bitsPerSample = int(buf[14]) | int(buf[15])<<8
if bitsPerSample != 8 && bitsPerSample != 16 {
return nil, fmt.Errorf("wav: bits per sample must be 8 or 16 but was %d", bitsPerSample)
}
sampleRate := int64(buf[4]) | int64(buf[5])<<8 | int64(buf[6])<<16 | int64(buf[7])<<24
if int64(context.SampleRate()) != sampleRate {
sampleRateFrom = int(sampleRate)
sampleRateTo = context.SampleRate()
}
headerSize += size
case bytes.Equal(buf[0:4], []byte("data")):
dataSize = size
break chunks
default:
buf := make([]byte, size)
n, err := io.ReadFull(src, buf)
if n != len(buf) {
return nil, fmt.Errorf("wav: invalid header")
}
if err != nil {
return nil, err
}
headerSize += size
}
}
var s audio.ReadSeekCloser = &stream{
src: src,
headerSize: headerSize,
dataSize: dataSize,
remaining: dataSize,
}
if mono || bitsPerSample != 16 {
s = convert.NewStereo16(s, mono, bitsPerSample != 16)
if mono {
dataSize *= 2
}
if bitsPerSample != 16 {
dataSize *= 2
}
}
if sampleRateFrom != sampleRateTo {
s = convert.NewResampling(s, dataSize, sampleRateFrom, sampleRateTo)
dataSize = dataSize * int64(sampleRateTo) / int64(sampleRateFrom)
}
return &Stream{s, dataSize}, nil
}