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package wav
// #define DR_WAV_IMPLEMENTATION
// #include "dr_wav.h"
import "C"
import (
"fmt"
"github.com/op/go-logging"
"layeh.com/gopus"
)
// number of individual samples per batch (counting all channels)
const samplesPerBatch = 1920
var log = logging.MustGetLogger("wav")
func Load(filename string) (<-chan []byte, <-chan struct{}, error) {
cfname := C.CString(filename)
wav := C.drwav_open_file(cfname)
if wav == nil {
return nil, nil, fmt.Errorf("Unable to initialize drwav.")
}
if int(wav.channels) != 2 {
C.drwav_close(wav)
return nil, nil, fmt.Errorf("Wrong number of channels!")
}
if int(wav.sampleRate) != 48000 {
C.drwav_close(wav)
return nil, nil, fmt.Errorf("Wrong sample rate.")
}
ch := make(chan []byte, 1024*32)
enc, err := gopus.NewEncoder(int(wav.sampleRate), int(wav.channels), gopus.Audio)
if err != nil {
return nil, nil, err
}
doneCh := make(chan struct{})
encoderCh := make(chan []int16, 2*48000*2)
go func() {
buf := C.malloc(C.size_t(samplesPerBatch * wav.bytesPerSample))
defer C.free(buf)
defer C.drwav_close(wav)
for i := 0; i < (int(wav.totalSampleCount)/samplesPerBatch)+1; i++ {
readSamples := C.drwav_read_s16(wav, samplesPerBatch, (*C.dr_int16)(buf))
slc := (*[1 << 30]int16)(buf)[:readSamples:readSamples]
encoderCh <- slc
if readSamples < samplesPerBatch {
break
}
}
close(encoderCh)
}()
go func(channels int) {
elems := []int16{}
for v := range encoderCh {
elems = append(elems, v...)
if len(elems) > samplesPerBatch*channels {
opus, err := enc.Encode(elems[:samplesPerBatch*channels], samplesPerBatch, samplesPerBatch*channels*2)
elems = elems[samplesPerBatch*channels:]
if err != nil {
log.Errorf("Error encoding opus audio: %q", err)
continue
}
ch <- opus
}
}
close(ch)
close(doneCh)
}(int(wav.channels))
return ch, doneCh, nil
}
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