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audio/vorbis: refactoring
This commit is contained in:
Hajime Hoshi
parent
b0a4b6ebbf
commit
5942192b66
@ -27,28 +27,28 @@ import (
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// Stream is a decoded audio stream.
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type Stream struct {
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decoded io.ReadSeeker
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size int64
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readSeeker io.ReadSeeker
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length int64
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sampleRate int
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}
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// Read is implementation of io.Reader's Read.
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func (s *Stream) Read(p []byte) (int, error) {
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return s.decoded.Read(p)
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return s.readSeeker.Read(p)
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}
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// Seek is implementation of io.Seeker's Seek.
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//
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// Note that Seek can take long since decoding is a relatively heavy task.
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func (s *Stream) Seek(offset int64, whence int) (int64, error) {
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return s.decoded.Seek(offset, whence)
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return s.readSeeker.Seek(offset, whence)
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}
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// Length returns the size of decoded stream in bytes.
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//
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// If the source is not io.Seeker, Length returns 0.
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func (s *Stream) Length() int64 {
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return s.size
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return s.length
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}
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// SampleRate returns the sample rate of the decoded stream.
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@ -56,27 +56,19 @@ func (s *Stream) SampleRate() int {
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return s.sampleRate
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}
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type decoder interface {
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Read([]float32) (int, error)
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SetPosition(int64) error
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Length() int64
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Channels() int
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SampleRate() int
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type i16Stream struct {
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totalBytes int
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posInBytes int
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vorbisReader *oggvorbis.Reader
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i16Reader io.Reader
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}
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type decoded struct {
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totalBytes int
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posInBytes int
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decoder decoder
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decoderr io.Reader
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}
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func (d *decoded) Read(b []byte) (int, error) {
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if d.decoderr == nil {
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d.decoderr = convert.NewReaderFromFloat32Reader(d.decoder)
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func (s *i16Stream) Read(b []byte) (int, error) {
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if s.i16Reader == nil {
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s.i16Reader = convert.NewReaderFromFloat32Reader(s.vorbisReader)
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}
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l := d.totalBytes - d.posInBytes
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l := s.totalBytes - s.posInBytes
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if l > len(b) {
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l = len(b)
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}
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@ -85,7 +77,7 @@ func (d *decoded) Read(b []byte) (int, error) {
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}
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retry:
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n, err := d.decoderr.Read(b[:l])
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n, err := s.i16Reader.Read(b[:l])
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if err != nil && err != io.EOF {
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return 0, err
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}
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@ -94,59 +86,63 @@ retry:
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goto retry
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}
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d.posInBytes += n
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if d.posInBytes == d.totalBytes || err == io.EOF {
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s.posInBytes += n
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if s.posInBytes == s.totalBytes || err == io.EOF {
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return n, io.EOF
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}
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return n, nil
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}
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func (d *decoded) Seek(offset int64, whence int) (int64, error) {
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func (s *i16Stream) Seek(offset int64, whence int) (int64, error) {
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next := int64(0)
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switch whence {
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case io.SeekStart:
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next = offset
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case io.SeekCurrent:
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next = int64(d.posInBytes) + offset
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next = int64(s.posInBytes) + offset
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case io.SeekEnd:
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next = int64(d.totalBytes) + offset
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next = int64(s.totalBytes) + offset
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}
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// pos should be always even
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next = next / 2 * 2
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d.posInBytes = int(next)
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if err := d.decoder.SetPosition(next / int64(d.decoder.Channels()) / 2); err != nil {
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s.posInBytes = int(next)
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if err := s.vorbisReader.SetPosition(next / int64(s.vorbisReader.Channels()) / 2); err != nil {
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return 0, err
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}
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d.decoderr = nil
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s.i16Reader = nil
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return next, nil
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}
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func (d *decoded) Length() int64 {
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return int64(d.totalBytes)
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func (s *i16Stream) Length() int64 {
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return int64(s.totalBytes)
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}
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// decode accepts an ogg stream and returns a decorded stream.
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func decode(in io.Reader) (*decoded, int, int, error) {
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func decode(in io.Reader) (*i16Stream, int, int, error) {
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r, err := oggvorbis.NewReader(in)
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if err != nil {
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return nil, 0, 0, err
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}
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d := &decoded{
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if r.Channels() != 1 && r.Channels() != 2 {
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return nil, 0, 0, fmt.Errorf("vorbis: number of channels must be 1 or 2 but was %d", r.Channels())
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}
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s := &i16Stream{
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// TODO: r.Length() returns 0 when the format is unknown.
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// Should we check that?
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totalBytes: int(r.Length()) * r.Channels() * 2, // 2 means 16bit per sample.
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posInBytes: 0,
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decoder: r,
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totalBytes: int(r.Length()) * r.Channels() * 2, // 2 means 16bit per sample.
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posInBytes: 0,
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vorbisReader: r,
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}
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if _, ok := in.(io.Seeker); ok {
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if _, err := d.Read(make([]byte, 65536)); err != nil && err != io.EOF {
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if _, err := s.Read(make([]byte, 65536)); err != nil && err != io.EOF {
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return nil, 0, 0, err
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}
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if _, err := d.Seek(0, io.SeekStart); err != nil {
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if _, err := s.Seek(0, io.SeekStart); err != nil {
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return nil, 0, 0, err
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}
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}
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return d, r.Channels(), r.SampleRate(), nil
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return s, r.Channels(), r.SampleRate(), nil
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}
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// DecodeWithoutResampling decodes Ogg/Vorbis data to playable stream.
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@ -158,22 +154,21 @@ func decode(in io.Reader) (*decoded, int, int, error) {
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// A Stream doesn't close src even if src implements io.Closer.
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// Closing the source is src owner's responsibility.
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func DecodeWithoutResampling(src io.Reader) (*Stream, error) {
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decoded, channelCount, sampleRate, err := decode(src)
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i16Stream, channelCount, sampleRate, err := decode(src)
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if err != nil {
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return nil, err
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}
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if channelCount != 1 && channelCount != 2 {
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return nil, fmt.Errorf("vorbis: number of channels must be 1 or 2 but was %d", channelCount)
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}
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var s io.ReadSeeker = decoded
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size := decoded.Length()
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var s io.ReadSeeker = i16Stream
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length := i16Stream.Length()
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if channelCount == 1 {
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s = convert.NewStereo16(s, true, false)
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size *= 2
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length *= 2
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}
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stream := &Stream{
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decoded: s,
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size: size,
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readSeeker: s,
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length: length,
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sampleRate: sampleRate,
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}
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return stream, nil
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@ -193,27 +188,25 @@ func DecodeWithoutResampling(src io.Reader) (*Stream, error) {
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// Resampling can be a very heavy task. Stream has a cache for resampling, but the size is limited.
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// Do not expect that Stream has a resampling cache even after whole data is played.
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func DecodeWithSampleRate(sampleRate int, src io.Reader) (*Stream, error) {
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decoded, channelCount, origSampleRate, err := decode(src)
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i16Stream, channelCount, origSampleRate, err := decode(src)
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if err != nil {
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return nil, err
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}
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if channelCount != 1 && channelCount != 2 {
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return nil, fmt.Errorf("vorbis: number of channels must be 1 or 2 but was %d", channelCount)
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}
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var s io.ReadSeeker = decoded
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size := decoded.Length()
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var s io.ReadSeeker = i16Stream
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length := i16Stream.Length()
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if channelCount == 1 {
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s = convert.NewStereo16(s, true, false)
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size *= 2
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length *= 2
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}
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if origSampleRate != sampleRate {
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r := convert.NewResampling(s, size, origSampleRate, sampleRate)
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r := convert.NewResampling(s, length, origSampleRate, sampleRate)
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s = r
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size = r.Length()
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length = r.Length()
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}
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stream := &Stream{
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decoded: s,
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size: size,
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readSeeker: s,
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length: length,
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sampleRate: sampleRate,
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}
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return stream, nil
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