func (d *Decoder) readNextPage(frame *[][]float32, pcm [][][]float32) (n int, err error) {
if ret := vorbis.OggSyncPageout(&d.syncState, &d.page); ret < 0 {
d.onError(errors.New("vorbis: corrupt or missing data in bitstream"))
return 0, nil // non-fatal
} else if ret == 0 {
// need more data
return d.readChunk(d.input)
}
// page is synced at this point
vorbis.OggStreamPagein(&d.streamState, &d.page)
for !d.stopRequested() {
if ret := vorbis.OggStreamPacketout(&d.streamState, &d.packet); ret < 0 {
continue // skip packet
} else if ret == 0 {
// no packets left on the page, go to the new one
return 0, nil
}
if vorbis.Synthesis(&d.block, &d.packet) == 0 {
vorbis.SynthesisBlockin(&d.dspState, &d.block)
}
samples := vorbis.SynthesisPcmout(&d.dspState, pcm)
for ; samples > 0; samples = vorbis.SynthesisPcmout(&d.dspState, pcm) {
space := int32(d.samplesPerChannel - len(*frame))
if samples > space {
samples = space
}
for i := 0; i < int(samples); i++ {
sample := make([]float32, d.info.Channels)
for j := 0; j < int(d.info.Channels); j++ {
sample[j] = pcm[0][j][:samples][i]
}
*frame = append(*frame, sample)
}
if len(*frame) == d.samplesPerChannel {
d.sendFrame(*frame)
*frame = make([][]float32, 0, d.samplesPerChannel)
}
vorbis.SynthesisRead(&d.dspState, samples)
}
}
if d.stopRequested() || vorbis.OggPageEos(&d.page) == 1 {
return 0, io.EOF
}
return 0, nil
}
func (d *Decoder) readStreamHeaders(r io.Reader) error {
d.readChunk(r)
// Read the first page
if ret := vorbis.OggSyncPageout(&d.syncState, &d.page); ret != 1 {
return errors.New("vorbis: not a valid Ogg bitstream")
}
// Init the logical bitstream with serial number stored in the page
vorbis.OggStreamInit(&d.streamState, vorbis.OggPageSerialno(&d.page))
vorbis.InfoInit(&d.info)
vorbis.CommentInit(&d.comment)
// Add a complete page to the bitstream
if ret := vorbis.OggStreamPagein(&d.streamState, &d.page); ret < 0 {
return errors.New("vorbis: the supplied page does not belong this Vorbis stream")
}
// Get the first packet
if ret := vorbis.OggStreamPacketout(&d.streamState, &d.packet); ret != 1 {
return errors.New("vorbis: unable to fetch initial Vorbis packet from the first page")
}
// Finally decode the header packet
if ret := vorbis.SynthesisHeaderin(&d.info, &d.comment, &d.packet); ret < 0 {
return fmt.Errorf("vorbis: unable to decode the initial Vorbis header: %d", ret)
}
var headersRead int
forPage:
for headersRead < 2 {
if res := vorbis.OggSyncPageout(&d.syncState, &d.page); res < 0 {
// bytes have been skipped, try to sync again
continue forPage
} else if res == 0 {
// go get more data
if _, err := d.readChunk(r); err != nil {
return errors.New("vorbis: got EOF while reading Vorbis headers")
}
continue forPage
}
// page is synced at this point
vorbis.OggStreamPagein(&d.streamState, &d.page)
for headersRead < 2 {
if ret := vorbis.OggStreamPacketout(&d.streamState, &d.packet); ret < 0 {
return errors.New("vorbis: data is missing near the secondary Vorbis header")
} else if ret == 0 {
// no packets left on the page, go get a new one
continue forPage
}
if ret := vorbis.SynthesisHeaderin(&d.info, &d.comment, &d.packet); ret < 0 {
return errors.New("vorbis: unable to read the secondary Vorbis header")
}
headersRead++
}
}
d.info.Deref()
d.comment.Deref()
d.comment.UserComments = make([][]byte, d.comment.Comments)
d.comment.Deref()
return nil
}