func (s *SystemPort) Open() error {
if s.isOpen && s.stream == nil {
return errors.New("Underlying portmidi port is already opened, " +
"but stream is not connected to this SystemPort.")
}
if s.id == -1 || s.isOpen { // Fake port or opened already, ignore.
return nil
}
var errNum C.PmError
if s.IsInputPort {
// The input / output naming LOOKS backwards, but we're opening a
// portmidi "output stream" for input Ports and vice versa.
errNum = C.Pm_OpenOutput(&(s.stream), C.PmDeviceID(s.id),
nil, C.int32_t(512), nil, nil, 0)
} else {
errNum = C.Pm_OpenInput(&(s.stream), C.PmDeviceID(s.id),
nil, C.int32_t(512), nil, nil)
}
if errNum == 0 {
s.isOpen = true
s.stop = make(chan bool, 1)
s.noteOns = make(chan Note, BufferSize)
s.noteOffs = make(chan Note, BufferSize)
s.controlChanges = make(chan ControlChange, BufferSize)
}
return makePortMidiError(errNum)
}
// Initializes a new output stream.
func NewOutputStream(deviceId DeviceId, bufferSize int64, latency int64) (stream *Stream, err error) {
var str *C.PmStream
errCode := C.Pm_OpenOutput(
(*unsafe.Pointer)(unsafe.Pointer(&str)),
C.PmDeviceID(deviceId), nil, C.int32_t(bufferSize), nil, nil, C.int32_t(latency))
if errCode != 0 {
return nil, convertToError(errCode)
}
return &Stream{deviceId: deviceId, pmStream: str}, nil
}
// NewOutputStream initializes a new output stream.
func NewOutputStream(id DeviceID, bufferSize int64, latency int64) (stream *Stream, err error) {
var str *C.PmStream
errCode := C.Pm_OpenOutput(
(*unsafe.Pointer)(unsafe.Pointer(&str)),
C.PmDeviceID(id), nil, C.int32_t(bufferSize), nil, nil, C.int32_t(latency))
if errCode != 0 {
return nil, convertToError(errCode)
}
if info := Info(id); !info.IsOutputAvailable {
return nil, ErrOutputUnavailable
}
return &Stream{deviceID: id, pmStream: str}, nil
}