func newEcho(delay time.Duration) *echo {
h, err := portaudio.DefaultHostApi()
chk(err)
p := portaudio.LowLatencyParameters(h.DefaultInputDevice, h.DefaultOutputDevice)
p.Input.Channels = 1
p.Output.Channels = 1
e := &echo{buffer: make([]float32, int(p.SampleRate*delay.Seconds()))}
e.Stream, err = portaudio.OpenStream(p, e.processAudio)
chk(err)
return e
}
func (a *Audio) Start() error {
host, err := portaudio.DefaultHostApi()
if err != nil {
return err
}
parameters := portaudio.HighLatencyParameters(nil, host.DefaultOutputDevice)
stream, err := portaudio.OpenStream(parameters, a.Callback)
if err != nil {
return err
}
if err := stream.Start(); err != nil {
return err
}
a.stream = stream
return nil
}
func main() {
portaudio.Initialize()
defer portaudio.Terminate()
h, err := portaudio.DefaultHostApi()
chk(err)
stream, err := portaudio.OpenStream(portaudio.HighLatencyParameters(nil, h.DefaultOutputDevice), func(out []int32) {
for i := range out {
out[i] = int32(rand.Uint32())
}
})
chk(err)
defer stream.Close()
chk(stream.Start())
time.Sleep(time.Second)
chk(stream.Stop())
}
func (m *Meter) Initialize() {
hs, err := portaudio.HostApis()
if err != nil {
fmt.Println("portaudio.HostApis failed:", err)
panic(err)
}
m.Fast = make(map[string]*MeterFast)
m.Fast["i"] = &MeterFast{}
m.Fast["o"] = &MeterFast{}
for _, hai := range hs {
apistr := hai.Type.String()
if hai.Name != apistr {
apistr = fmt.Sprintf("%s \"%s\"", apistr, hai.Name)
}
all := make(map[string][]*MeterFastDev)
for k := range m.Fast {
all[k] = make([]*MeterFastDev, 0, len(hai.Devices))
}
minLatency := make(map[string]float64)
for i, d := range hai.Devices {
appendLowLatency := func(k string, numch int, latency float64) {
// some devices do not support low latency, indicated by a latency of -1
if numch > 0 && latency > 0 {
all[k] = append(all[k], &MeterFastDev{"", i, d, latency})
cur, ok := minLatency[k]
if !ok || cur > latency {
minLatency[k] = latency
}
}
}
appendLowLatency("i", d.MaxInputChannels, d.DefaultLowInputLatency.Seconds())
appendLowLatency("o", d.MaxOutputChannels, d.DefaultLowOutputLatency.Seconds())
}
for k, s := range all {
for _, d := range s {
if (d.Latency - minLatency[k]) >= 1e-3 {
continue
}
d.Name = d.DevInfo.Name
switch {
case hai.DefaultInputDevice == d.DevInfo && hai.DefaultOutputDevice == d.DevInfo:
d.Name = d.Name + " (default_in_out)"
case hai.DefaultInputDevice == d.DevInfo:
d.Name = d.Name + " (default_in)"
case hai.DefaultOutputDevice == d.DevInfo:
d.Name = d.Name + " (default_out)"
}
m.Fast[k].Dev = append(m.Fast[k].Dev, d)
}
}
}
for k, s := range m.Fast {
if len(s.Dev) < 1 {
fmt.Printf("Warning(ch.%s): no known latency on any device. making something up...", k)
h, err := portaudio.DefaultHostApi()
if err != nil {
fmt.Printf("portaudio.DefaultHostApi failed: ", err)
panic(err)
}
defdev := make(map[string]*portaudio.DeviceInfo)
defdev["i"] = h.DefaultInputDevice
defdev["o"] = h.DefaultOutputDevice
m.Fast[k].Dev = append(m.Fast[k].Dev, &MeterFastDev{
Name: "defdev" + k,
haiIndex: 0, // Completely made up.
DevInfo: defdev[k],
Latency: 1000, // Completely made up.
})
}
}
}