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av/stream/flac: working on cleaning up decode code

This commit is contained in:
saxon 2019-01-22 10:26:22 +10:30
parent 5f3bf33213
commit 7628efdbc2
1 changed files with 24 additions and 19 deletions
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43
stream/flac/decode.go
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@ -90,7 +90,8 @@ func (ws *writeSeeker) Seek(offset int64, whence int) (int64, error) {
// Decode takes buf, a slice of FLAC, and decodes to WAV. If complete decoding // Decode takes buf, a slice of FLAC, and decodes to WAV. If complete decoding
// fails, an error is returned. // fails, an error is returned.
func Decode(buf []byte) ([]byte, error) { func Decode(buf []byte) ([]byte, error) {
// Lex and decode the FLAC into a stream to hold audio and properties.
// Lex the FLAC into a stream to hold audio and it's properties.
r := bytes.NewReader(buf) r := bytes.NewReader(buf)
stream, err := flac.Parse(r) stream, err := flac.Parse(r)
if err != nil { if err != nil {
@ -99,17 +100,30 @@ func Decode(buf []byte) ([]byte, error) {
// Create WAV encoder and pass writeSeeker that will store output WAV. // Create WAV encoder and pass writeSeeker that will store output WAV.
ws := &writeSeeker{} ws := &writeSeeker{}
enc := wav.NewEncoder(ws, int(stream.Info.SampleRate), int(stream.Info.BitsPerSample), int(stream.Info.NChannels), wavFormat) sr := int(stream.Info.SampleRate)
bps := int(stream.Info.BitsPerSample)
nc := int(stream.Info.NChannels)
enc := wav.NewEncoder(ws, sr, bps, nc, wavFormat)
defer enc.Close() defer enc.Close()
// Decode FLAC into frames of samples
intBuf := &audio.IntBuffer{
Format: &audio.Format{NumChannels: nc, SampleRate: sr},
SourceBitDepth: bps,
}
return decodeFrames(stream, intBuf, enc, ws)
}
//
func decodeFrames(s *flac.Stream, intBuf *audio.IntBuffer, e *wav.Encoder, ws *writeSeeker) ([]byte, error) {
var data []int var data []int
for { for {
// Decode FLAC audio samples. frame, err := s.ParseNext()
frame, err := stream.ParseNext()
if err != nil { // If we've reached the end of the stream then we can output the writeSeeker's buffer.
if err == io.EOF { if err == io.EOF {
break return ws.Bytes(), nil
} } else if err != nil {
return nil, err return nil, err
} }
@ -120,18 +134,9 @@ func Decode(buf []byte) ([]byte, error) {
data = append(data, int(subframe.Samples[i])) data = append(data, int(subframe.Samples[i]))
} }
} }
buf := &audio.IntBuffer{ intBuf.Data = data
Format: &audio.Format{ if err := e.Write(intBuf); err != nil {
NumChannels: int(stream.Info.NChannels),
SampleRate: int(stream.Info.SampleRate),
},
Data: data,
SourceBitDepth: int(stream.Info.BitsPerSample),
}
if err := enc.Write(buf); err != nil {
return nil, err return nil, err
} }
} }
return ws.Bytes(), nil
} }