124 lines
2.8 KiB
Go
124 lines
2.8 KiB
Go
package wav
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import (
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"io"
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"time"
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"github.com/pkg/errors"
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)
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type Streamer struct {
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rc io.ReadCloser
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h header
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pos int32
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err error
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}
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func NewStreamer(rc io.ReadCloser) (*Streamer, error) {
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var (
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d Streamer
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err error
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)
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d.rc = rc
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d.h, err = readHeader(rc)
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if err != nil {
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rc.Close()
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return nil, errors.Wrap(err, "wav")
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}
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if d.h.formatType != 1 {
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rc.Close()
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return nil, errors.New("wav: unsupported format type")
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}
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if d.h.numChans <= 0 {
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rc.Close()
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return nil, errors.New("wav: invalid number of channels (less than 1)")
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}
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if d.h.bitsPerSample != 8 && d.h.bitsPerSample != 16 {
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rc.Close()
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return nil, errors.New("wav: unsupported number of bits per sample, 8 or 16 are supported")
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}
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return &d, nil
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}
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func (d *Streamer) Err() error {
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return d.err
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}
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func (d *Streamer) Duration() time.Duration {
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numBytes := time.Duration(d.h.dataSize)
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perFrame := time.Duration(d.h.bytesPerFrame)
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sampRate := time.Duration(d.h.sampleRate)
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return numBytes / perFrame * time.Second / sampRate
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}
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func (d *Streamer) Stream(samples [][2]float64) (n int, ok bool) {
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if d.pos >= d.h.dataSize {
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return 0, false
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}
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switch {
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case d.h.bitsPerSample == 8 && d.h.numChans == 1:
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width := 1
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p := make([]byte, len(samples)*width)
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n, err := d.rc.Read(p)
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for i, j := 0, 0; i < n-width; i, j = i+width, j+1 {
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val := float64(p[i])/255*2 - 1
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samples[j][0] = val
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samples[j][1] = val
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}
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if err != nil {
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d.err = err
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}
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d.pos += int32(n)
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return n / width, true
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case d.h.bitsPerSample == 8 && d.h.numChans >= 2:
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width := int(d.h.numChans)
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p := make([]byte, len(samples)*width)
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n, err := d.rc.Read(p)
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for i, j := 0, 0; i < n-width; i, j = i+width, j+1 {
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samples[j][0] = float64(p[i+0])/255*2 - 1
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samples[j][1] = float64(p[i+1])/255*2 - 1
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}
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if err != nil {
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d.err = err
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}
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d.pos += int32(n)
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return n / width, true
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case d.h.bitsPerSample == 16 && d.h.numChans == 1:
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width := 2
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p := make([]byte, len(samples)*width)
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n, err := d.rc.Read(p)
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for i, j := 0, 0; i < n-width; i, j = i+width, j+1 {
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val := float64(int16(p[i+0])+int16(p[i+1])*(1<<8)) / (1<<15 - 1)
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samples[j][0] = val
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samples[j][1] = val
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}
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if err != nil {
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d.err = err
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}
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d.pos += int32(n)
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return n / width, true
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case d.h.bitsPerSample == 16 && d.h.numChans >= 2:
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width := int(d.h.numChans) * 2
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p := make([]byte, len(samples)*width)
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n, err := d.rc.Read(p)
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for i, j := 0, 0; i <= n-width; i, j = i+width, j+1 {
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samples[j][0] = float64(int16(p[i+0])+int16(p[i+1])*(1<<8)) / (1<<15 - 1)
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samples[j][1] = float64(int16(p[i+2])+int16(p[i+3])*(1<<8)) / (1<<15 - 1)
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}
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if err != nil {
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d.err = err
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}
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d.pos += int32(n)
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return n / width, true
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}
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panic("unreachable")
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}
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func (d *Streamer) Close() error {
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err := d.rc.Close()
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if err != nil {
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return errors.Wrap(err, "wav")
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}
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return nil
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}
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