// Read reads samples into a buffer and returns the amount read.
func (c *CaptureDevice) Read(buffer interface{}) (samples int, err error) {
bufferType := reflect.TypeOf(buffer)
if !(bufferType.Kind() == reflect.Array ||
bufferType.Kind() == reflect.Slice) {
return 0, errors.New("Read requires an array type")
}
sizeError := errors.New("Read requires a matching sample size")
switch bufferType.Elem().Kind() {
case reflect.Int8:
if c.formatSampleSize() != 1 {
return 0, sizeError
}
case reflect.Int16:
if c.formatSampleSize() != 2 {
return 0, sizeError
}
case reflect.Int32, reflect.Float32:
if c.formatSampleSize() != 4 {
return 0, sizeError
}
case reflect.Float64:
if c.formatSampleSize() != 8 {
return 0, sizeError
}
default:
return 0, errors.New("Read does not support this format")
}
val := reflect.ValueOf(buffer)
length := val.Len()
sliceData := val.Slice(0, length)
var frames = C.snd_pcm_uframes_t(length / c.Channels)
bufPtr := unsafe.Pointer(sliceData.Index(0).Addr().Pointer())
ret := C.snd_pcm_readi(c.h, bufPtr, frames)
if ret == -C.EPIPE {
C.snd_pcm_prepare(c.h)
return 0, ErrOverrun
} else if ret < 0 {
return 0, createError("read error", C.int(ret))
}
samples = int(ret) * c.Channels
return
}
// Write writes given PCM data.
// Returns wrote value is total bytes was written.
func (handle *Handle) Write(buf []byte) (wrote int, err error) {
frames := len(buf) / handle.SampleSize() / handle.Channels
w := C.snd_pcm_writei(handle.cHandle, unsafe.Pointer(&buf[0]), _Ctype_snd_pcm_uframes_t(frames))
// Underrun? Retry.
if w == -C.EPIPE {
C.snd_pcm_prepare(handle.cHandle)
w = C.snd_pcm_writei(handle.cHandle, unsafe.Pointer(&buf[0]), _Ctype_snd_pcm_uframes_t(frames))
}
if w < 0 {
return 0, errors.New(fmt.Sprintf("Write failed. %s", strError(_Ctype_int(w))))
}
wrote = int(w)
wrote *= handle.FrameSize()
return wrote, nil
}