audio/wav: add (*Stream).SampleRate

Closes #2996
This commit is contained in:
Hajime Hoshi 2024-05-18 20:19:27 +09:00
parent ac83181403
commit a612e74031

View File

@ -26,8 +26,9 @@ import (
// Stream is a decoded audio stream.
type Stream struct {
inner io.ReadSeeker
size int64
inner io.ReadSeeker
size int64
sampleRate int
}
// Read is implementation of io.Reader's Read.
@ -49,6 +50,11 @@ func (s *Stream) Length() int64 {
return s.size
}
// SampleRate returns the sample rate of the decoded stream.
func (s *Stream) SampleRate() int {
return s.sampleRate
}
type stream struct {
src io.Reader
headerSize int64
@ -114,7 +120,7 @@ func (s *stream) Seek(offset int64, whence int) (int64, error) {
// A Stream doesn't close src even if src implements io.Closer.
// Closing the source is src owner's responsibility.
func DecodeWithoutResampling(src io.Reader) (*Stream, error) {
s, _, err := decode(src)
s, err := decode(src)
if err != nil {
return nil, err
}
@ -138,36 +144,37 @@ func DecodeWithoutResampling(src io.Reader) (*Stream, error) {
// Resampling can be a very heavy task. Stream has a cache for resampling, but the size is limited.
// Do not expect that Stream has a resampling cache even after whole data is played.
func DecodeWithSampleRate(sampleRate int, src io.Reader) (*Stream, error) {
s, origSampleRate, err := decode(src)
s, err := decode(src)
if err != nil {
return nil, err
}
if sampleRate == origSampleRate {
if sampleRate == s.sampleRate {
return s, nil
}
r := convert.NewResampling(s.inner, s.size, origSampleRate, sampleRate)
r := convert.NewResampling(s.inner, s.size, s.sampleRate, sampleRate)
return &Stream{
inner: r,
size: r.Length(),
inner: r,
size: r.Length(),
sampleRate: sampleRate,
}, nil
}
func decode(src io.Reader) (*Stream, int, error) {
func decode(src io.Reader) (*Stream, error) {
buf := make([]byte, 12)
n, err := io.ReadFull(src, buf)
if n != len(buf) {
return nil, 0, fmt.Errorf("wav: invalid header")
return nil, fmt.Errorf("wav: invalid header")
}
if err != nil {
return nil, 0, err
return nil, err
}
if !bytes.Equal(buf[0:4], []byte("RIFF")) {
return nil, 0, fmt.Errorf("wav: invalid header: 'RIFF' not found")
return nil, fmt.Errorf("wav: invalid header: 'RIFF' not found")
}
if !bytes.Equal(buf[8:12], []byte("WAVE")) {
return nil, 0, fmt.Errorf("wav: invalid header: 'WAVE' not found")
return nil, fmt.Errorf("wav: invalid header: 'WAVE' not found")
}
// Read chunks
@ -181,10 +188,10 @@ chunks:
buf := make([]byte, 8)
n, err := io.ReadFull(src, buf)
if n != len(buf) {
return nil, 0, fmt.Errorf("wav: invalid header")
return nil, fmt.Errorf("wav: invalid header")
}
if err != nil {
return nil, 0, err
return nil, err
}
headerSize += 8
size := int64(buf[4]) | int64(buf[5])<<8 | int64(buf[6])<<16 | int64(buf[7])<<24
@ -192,19 +199,19 @@ chunks:
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, 0, fmt.Errorf("wav: invalid header: maybe non-PCM file?")
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, 0, fmt.Errorf("wav: invalid header")
return nil, fmt.Errorf("wav: invalid header")
}
if err != nil {
return nil, 0, err
return nil, err
}
format := int(buf[0]) | int(buf[1])<<8
if format != 1 {
return nil, 0, fmt.Errorf("wav: format must be linear PCM")
return nil, fmt.Errorf("wav: format must be linear PCM")
}
channelCount := int(buf[2]) | int(buf[3])<<8
switch channelCount {
@ -213,11 +220,11 @@ chunks:
case 2:
mono = false
default:
return nil, 0, fmt.Errorf("wav: number of channels must be 1 or 2 but was %d", channelCount)
return nil, fmt.Errorf("wav: number of channels must be 1 or 2 but was %d", channelCount)
}
bitsPerSample = int(buf[14]) | int(buf[15])<<8
if bitsPerSample != 8 && bitsPerSample != 16 {
return nil, 0, fmt.Errorf("wav: bits per sample must be 8 or 16 but was %d", bitsPerSample)
return nil, fmt.Errorf("wav: bits per sample must be 8 or 16 but was %d", bitsPerSample)
}
sampleRate = int(buf[4]) | int(buf[5])<<8 | int(buf[6])<<16 | int(buf[7])<<24
headerSize += size
@ -228,10 +235,10 @@ chunks:
buf := make([]byte, size)
n, err := io.ReadFull(src, buf)
if n != len(buf) {
return nil, 0, fmt.Errorf("wav: invalid header")
return nil, fmt.Errorf("wav: invalid header")
}
if err != nil {
return nil, 0, err
return nil, err
}
headerSize += size
}
@ -252,7 +259,11 @@ chunks:
dataSize *= 2
}
}
return &Stream{inner: s, size: dataSize}, sampleRate, nil
return &Stream{
inner: s,
size: dataSize,
sampleRate: sampleRate,
}, nil
}
// Decode decodes WAV (RIFF) data to playable stream.