151 lines
3.5 KiB
Go
151 lines
3.5 KiB
Go
package wav
|
|
|
|
import (
|
|
"io"
|
|
"time"
|
|
|
|
"github.com/pkg/errors"
|
|
)
|
|
|
|
type ReadSeekCloser interface {
|
|
io.Reader
|
|
io.Seeker
|
|
io.Closer
|
|
}
|
|
|
|
type Streamer struct {
|
|
rsc ReadSeekCloser
|
|
h header
|
|
pos int32
|
|
err error
|
|
}
|
|
|
|
func NewStreamer(rsc ReadSeekCloser) (s *Streamer, err error) {
|
|
var (
|
|
d Streamer
|
|
herr error
|
|
)
|
|
d.rsc = rsc
|
|
defer func() { // hacky way to always close rsc if an error occured
|
|
if err != nil {
|
|
d.rsc.Close()
|
|
}
|
|
}()
|
|
d.h, herr = readHeader(rsc)
|
|
if herr != nil {
|
|
return nil, errors.Wrap(herr, "wav")
|
|
}
|
|
if d.h.formatType != 1 {
|
|
return nil, errors.New("wav: unsupported format type")
|
|
}
|
|
if d.h.numChans <= 0 {
|
|
return nil, errors.New("wav: invalid number of channels (less than 1)")
|
|
}
|
|
if d.h.bitsPerSample != 8 && d.h.bitsPerSample != 16 {
|
|
return nil, errors.New("wav: unsupported number of bits per sample, 8 or 16 are supported")
|
|
}
|
|
return &d, nil
|
|
}
|
|
|
|
func (s *Streamer) Err() error {
|
|
return s.err
|
|
}
|
|
|
|
func (s *Streamer) Duration() time.Duration {
|
|
numBytes := time.Duration(s.h.dataSize)
|
|
perFrame := time.Duration(s.h.bytesPerFrame)
|
|
sampRate := time.Duration(s.h.sampleRate)
|
|
return numBytes / perFrame * time.Second / sampRate
|
|
}
|
|
|
|
func (s *Streamer) Position() time.Duration {
|
|
frameIndex := time.Duration(s.pos / int32(s.h.bytesPerFrame))
|
|
frameTime := time.Second / time.Duration(s.h.sampleRate)
|
|
return frameIndex * frameTime
|
|
}
|
|
|
|
func (s *Streamer) Seek(d time.Duration) {
|
|
if d < 0 || s.Duration() < d {
|
|
panic("wav: seek duration out of range")
|
|
}
|
|
frame := int32(d / (time.Second / time.Duration(s.h.sampleRate)))
|
|
pos := frame * int32(s.h.bytesPerFrame)
|
|
_, err := s.rsc.Seek(int64(pos)+44, io.SeekStart) // 44 is the size of the header
|
|
if err != nil {
|
|
s.err = err
|
|
return
|
|
}
|
|
s.pos = pos
|
|
}
|
|
|
|
func (s *Streamer) Stream(samples [][2]float64) (n int, ok bool) {
|
|
if s.pos >= s.h.dataSize {
|
|
return 0, false
|
|
}
|
|
switch {
|
|
case s.h.bitsPerSample == 8 && s.h.numChans == 1:
|
|
width := 1
|
|
p := make([]byte, len(samples)*width)
|
|
n, err := s.rsc.Read(p)
|
|
for i, j := 0, 0; i < n-width; i, j = i+width, j+1 {
|
|
val := float64(p[i])/(1<<8-1)*2 - 1
|
|
samples[j][0] = val
|
|
samples[j][1] = val
|
|
}
|
|
if err != nil {
|
|
s.err = err
|
|
}
|
|
s.pos += int32(n)
|
|
return n / width, true
|
|
case s.h.bitsPerSample == 8 && s.h.numChans >= 2:
|
|
width := int(s.h.numChans)
|
|
p := make([]byte, len(samples)*width)
|
|
n, err := s.rsc.Read(p)
|
|
for i, j := 0, 0; i < n-width; i, j = i+width, j+1 {
|
|
samples[j][0] = float64(p[i+0])/(1<<8-1)*2 - 1
|
|
samples[j][1] = float64(p[i+1])/(1<<8-1)*2 - 1
|
|
}
|
|
if err != nil {
|
|
s.err = err
|
|
}
|
|
s.pos += int32(n)
|
|
return n / width, true
|
|
case s.h.bitsPerSample == 16 && s.h.numChans == 1:
|
|
width := 2
|
|
p := make([]byte, len(samples)*width)
|
|
n, err := s.rsc.Read(p)
|
|
for i, j := 0, 0; i < n-width; i, j = i+width, j+1 {
|
|
val := float64(int16(p[i+0])+int16(p[i+1])*(1<<8)) / (1<<15 - 1)
|
|
samples[j][0] = val
|
|
samples[j][1] = val
|
|
}
|
|
if err != nil {
|
|
s.err = err
|
|
}
|
|
s.pos += int32(n)
|
|
return n / width, true
|
|
case s.h.bitsPerSample == 16 && s.h.numChans >= 2:
|
|
width := int(s.h.numChans) * 2
|
|
p := make([]byte, len(samples)*width)
|
|
n, err := s.rsc.Read(p)
|
|
for i, j := 0, 0; i <= n-width; i, j = i+width, j+1 {
|
|
samples[j][0] = float64(int16(p[i+0])+int16(p[i+1])*(1<<8)) / (1<<15 - 1)
|
|
samples[j][1] = float64(int16(p[i+2])+int16(p[i+3])*(1<<8)) / (1<<15 - 1)
|
|
}
|
|
if err != nil {
|
|
s.err = err
|
|
}
|
|
s.pos += int32(n)
|
|
return n / width, true
|
|
}
|
|
panic("unreachable")
|
|
}
|
|
|
|
func (s *Streamer) Close() error {
|
|
err := s.rsc.Close()
|
|
if err != nil {
|
|
return errors.Wrap(err, "wav")
|
|
}
|
|
return nil
|
|
}
|