audio: wav: simplify code, more DRY, encapsulate decoder type, only export Decode function
This commit is contained in:
faiface
parent
55c94b6cc5
commit
502347d987
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@ -0,0 +1,162 @@
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package wav
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import (
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"encoding/binary"
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"fmt"
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"io"
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"time"
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"github.com/faiface/pixel/audio"
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"github.com/pkg/errors"
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)
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type ReadSeekCloser interface {
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io.Reader
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io.Seeker
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io.Closer
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}
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func Decode(rsc ReadSeekCloser) (s audio.StreamSeekCloser, err error) {
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var d decoder
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d.rsc = rsc
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defer func() { // hacky way to always close rsc if an error occured
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if err != nil {
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d.rsc.Close()
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}
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}()
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herr := binary.Read(rsc, binary.LittleEndian, &d.h)
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if herr != nil {
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return nil, errors.Wrap(herr, "wav")
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}
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if string(d.h.RiffMark[:]) != "RIFF" {
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return nil, errors.New("wav: missing RIFF at the beginning")
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}
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if string(d.h.WaveMark[:]) != "WAVE" {
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return nil, errors.New("wav: unsupported file type")
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}
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if string(d.h.FmtMark[:]) != "fmt " {
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return nil, errors.New("wav: missing format chunk marker")
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}
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if string(d.h.DataMark[:]) != "data" {
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return nil, errors.New("wav: missing data chunk marker")
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}
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if d.h.FormatType != 1 {
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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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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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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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type header struct {
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RiffMark [4]byte
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FileSize int32
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WaveMark [4]byte
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FmtMark [4]byte
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FormatSize int32
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FormatType int16
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NumChans int16
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SampleRate int32
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ByteRate int32
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BytesPerFrame int16
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BitsPerSample int16
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DataMark [4]byte
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DataSize int32
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}
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type decoder struct {
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rsc ReadSeekCloser
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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 (s *decoder) Err() error {
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return s.err
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}
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func (s *decoder) Duration() time.Duration {
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numBytes := time.Duration(s.h.DataSize)
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perFrame := time.Duration(s.h.BytesPerFrame)
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sampRate := time.Duration(s.h.SampleRate)
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return numBytes / perFrame * time.Second / sampRate
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}
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func (s *decoder) Position() time.Duration {
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frameIndex := time.Duration(s.pos / int32(s.h.BytesPerFrame))
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frameTime := time.Second / time.Duration(s.h.SampleRate)
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return frameIndex * frameTime
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}
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func (s *decoder) Seek(d time.Duration) error {
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if d < 0 || s.Duration() < d {
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return fmt.Errorf("wav: seek duration %v out of range [%v, %v]", d, 0, s.Duration())
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}
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frame := int32(d / (time.Second / time.Duration(s.h.SampleRate)))
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pos := frame * int32(s.h.BytesPerFrame)
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_, err := s.rsc.Seek(int64(pos)+44, io.SeekStart) // 44 is the size of the header
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if err != nil {
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return errors.Wrap(err, "wav: seek error")
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}
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s.pos = pos
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return nil
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}
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func (s *decoder) Stream(samples [][2]float64) (n int, ok bool) {
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if s.err != nil || s.pos >= s.h.DataSize {
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return 0, false
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}
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var frameWidth int
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switch {
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case s.h.BitsPerSample == 8 && s.h.NumChans == 1:
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frameWidth = 1
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case s.h.BitsPerSample == 8 && s.h.NumChans >= 2:
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frameWidth = int(s.h.NumChans)
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case s.h.BitsPerSample == 16 && s.h.NumChans == 1:
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frameWidth = 2
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case s.h.BitsPerSample == 16 && s.h.NumChans >= 2:
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frameWidth = int(s.h.NumChans) * 2
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}
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p := make([]byte, len(samples)*frameWidth)
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n, err := s.rsc.Read(p)
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if err != nil {
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s.err = err
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}
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switch {
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case s.h.BitsPerSample == 8 && s.h.NumChans == 1:
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for i, j := 0, 0; i < n-frameWidth; i, j = i+frameWidth, j+1 {
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val := float64(p[i])/(1<<8-1)*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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case s.h.BitsPerSample == 8 && s.h.NumChans >= 2:
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for i, j := 0, 0; i < n-frameWidth; i, j = i+frameWidth, j+1 {
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samples[j][0] = float64(p[i+0])/(1<<8-1)*2 - 1
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samples[j][1] = float64(p[i+1])/(1<<8-1)*2 - 1
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}
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case s.h.BitsPerSample == 16 && s.h.NumChans == 1:
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for i, j := 0, 0; i < n-frameWidth; i, j = i+frameWidth, 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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case s.h.BitsPerSample == 16 && s.h.NumChans >= 2:
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for i, j := 0, 0; i <= n-frameWidth; i, j = i+frameWidth, 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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}
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return n / frameWidth, true
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}
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func (s *decoder) Close() error {
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err := s.rsc.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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@ -1,78 +0,0 @@
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package wav
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import (
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"encoding/binary"
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"io"
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"github.com/pkg/errors"
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)
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type header struct {
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fileSize int32
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formatSize int32
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formatType int16
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numChans int16
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sampleRate int32
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byteRate int32
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bytesPerFrame int16
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bitsPerSample int16
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dataSize int32
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}
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func readHeader(r io.Reader) (header, error) {
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var (
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h header
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er errReader
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)
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err := er.
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ReadString(r, "RIFF", errors.New("missing RIFF at the beginning")).
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ReadBinary(r, binary.LittleEndian, &h.fileSize).
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ReadString(r, "WAVE", errors.New("unsupported file type")).
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ReadString(r, "fmt\x00", errors.New("missing format chunk marker")).
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ReadBinary(r, binary.LittleEndian, &h.formatSize).
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ReadBinary(r, binary.LittleEndian, &h.formatType).
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ReadBinary(r, binary.LittleEndian, &h.numChans).
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ReadBinary(r, binary.LittleEndian, &h.sampleRate).
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ReadBinary(r, binary.LittleEndian, &h.byteRate).
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ReadBinary(r, binary.LittleEndian, &h.bytesPerFrame).
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ReadBinary(r, binary.LittleEndian, &h.bitsPerSample).
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ReadString(r, "data", errors.New("missing data chunk marker")).
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ReadBinary(r, binary.LittleEndian, &h.dataSize).
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Err()
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return h, err
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}
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type errReader struct {
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err error
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}
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func (e *errReader) ReadString(r io.Reader, s string, notThereErr error) *errReader {
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if e.err != nil {
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return e
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}
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buf := make([]byte, len(s))
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_, err := r.Read(buf)
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if err != nil {
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e.err = errors.Wrap(err, "error while reading header")
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return e
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}
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if string(buf) != s {
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e.err = errors.Wrap(err, "invalid header")
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}
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return e
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}
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func (e *errReader) ReadBinary(r io.Reader, order binary.ByteOrder, data interface{}) *errReader {
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if e.err != nil {
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return e
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}
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err := binary.Read(r, order, data)
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if err != nil {
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e.err = errors.Wrap(err, "invalid header")
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}
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return e
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}
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func (e *errReader) Err() error {
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return e.err
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}
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@ -1,154 +0,0 @@
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package wav
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import (
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"fmt"
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"io"
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"time"
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"github.com/faiface/pixel/audio"
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"github.com/pkg/errors"
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)
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type ReadSeekCloser interface {
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io.Reader
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io.Seeker
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io.Closer
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}
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type Streamer struct {
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rsc ReadSeekCloser
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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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var _ audio.StreamSeekCloser = (*Streamer)(nil)
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func NewStreamer(rsc ReadSeekCloser) (s *Streamer, err error) {
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var (
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d Streamer
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herr error
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)
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d.rsc = rsc
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defer func() { // hacky way to always close rsc if an error occured
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if err != nil {
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d.rsc.Close()
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}
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}()
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d.h, herr = readHeader(rsc)
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if herr != nil {
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return nil, errors.Wrap(herr, "wav")
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}
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if d.h.formatType != 1 {
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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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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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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 (s *Streamer) Err() error {
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return s.err
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}
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func (s *Streamer) Duration() time.Duration {
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numBytes := time.Duration(s.h.dataSize)
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perFrame := time.Duration(s.h.bytesPerFrame)
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sampRate := time.Duration(s.h.sampleRate)
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return numBytes / perFrame * time.Second / sampRate
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}
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func (s *Streamer) Position() time.Duration {
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frameIndex := time.Duration(s.pos / int32(s.h.bytesPerFrame))
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frameTime := time.Second / time.Duration(s.h.sampleRate)
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return frameIndex * frameTime
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}
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func (s *Streamer) Seek(d time.Duration) error {
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if d < 0 || s.Duration() < d {
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return fmt.Errorf("wav: seek duration %v out of range [%v, %v]", d, 0, s.Duration())
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}
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frame := int32(d / (time.Second / time.Duration(s.h.sampleRate)))
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pos := frame * int32(s.h.bytesPerFrame)
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_, err := s.rsc.Seek(int64(pos)+44, io.SeekStart) // 44 is the size of the header
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if err != nil {
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return errors.Wrap(err, "wav: seek error")
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}
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s.pos = pos
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return nil
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}
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func (s *Streamer) Stream(samples [][2]float64) (n int, ok bool) {
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if s.pos >= s.h.dataSize {
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return 0, false
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}
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switch {
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case s.h.bitsPerSample == 8 && s.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 := s.rsc.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])/(1<<8-1)*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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s.err = err
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}
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s.pos += int32(n)
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return n / width, true
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case s.h.bitsPerSample == 8 && s.h.numChans >= 2:
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width := int(s.h.numChans)
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p := make([]byte, len(samples)*width)
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n, err := s.rsc.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])/(1<<8-1)*2 - 1
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samples[j][1] = float64(p[i+1])/(1<<8-1)*2 - 1
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}
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if err != nil {
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s.err = err
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}
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s.pos += int32(n)
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return n / width, true
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case s.h.bitsPerSample == 16 && s.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 := s.rsc.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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s.err = err
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}
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s.pos += int32(n)
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return n / width, true
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case s.h.bitsPerSample == 16 && s.h.numChans >= 2:
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width := int(s.h.numChans) * 2
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p := make([]byte, len(samples)*width)
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n, err := s.rsc.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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s.err = err
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}
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s.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 (s *Streamer) Close() error {
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err := s.rsc.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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