How can I select a device to use for capture/playback manually?

[gen2brain]

How can I select a device to use for capture/playback manually?

[fbrozovic]

Sorry, I realized I could have been clearer with explaining how I'm trying to do this.

This is my attempt now, but I'm still getting the same error... I'm not really familiar with Cgo, so any help would be much appreciated.

...

infos, err := ctx.Devices(malgo.Duplex)
if err != nil {
	fmt.Println(err)
	os.Exit(1)
}

fmt.Println("Duplex devices")
for i, info := range infos {
	fmt.Printf("%d: %v, %s\n", i, info.ID, info.Name())
}
fmt.Println()

devConf1 := malgo.DeviceConfig {
	DeviceType: malgo.Duplex,
	SampleRate: 44100,
	Capture: malgo.SubConfig{
		DeviceID: &infos[0].ID,
		Format: malgo.FormatS16,
		Channels: 1,
	},
	Playback: malgo.SubConfig{
		DeviceID: &infos[0].ID,
		Format: malgo.FormatS16,
		Channels: 1,
	},
}

...

dev1, err := malgo.InitDevice(ctx.Context, devConf1, devCallbacks1)
if err != nil {
	fmt.Println(err)
	os.Exit(1)
}

...

[gen2brain]

Passing ID to what? You should not use DefaultDeviceConfig but create custom DeviceConfig instead, which should contain ID from context.Devices you want to use. I had some examples where I needed that, but cannot find it, though, it should not be difficult.

[gen2brain]

Ok, need to check and test, API was different.

[fbrozovic]

Have you had a chance to look at this yet?

[gen2brain]

No, didn't find time to check.

[i0x71]

I am having the same issue, will post here if i can get it to work.

[fbrozovic]

So I managed to get it to work by doing the following:

diff --git a/device_config.go b/device_config.go
index 3392191..f28010d 100644
--- a/device_config.go
+++ b/device_config.go
@@ -37,7 +37,7 @@ func (d *DeviceConfig) cptr() *C.ma_device_config {
 
 // SubConfig type.
 type SubConfig struct {
-       DeviceID   *DeviceID
+       DeviceID   unsafe.Pointer
        Format     FormatType
        Channels   uint32
        ChannelMap [C.MA_MAX_CHANNELS]uint8
diff --git a/device_info.go b/device_info.go
index dc7eb59..1e07d10 100644
--- a/device_info.go
+++ b/device_info.go
@@ -21,8 +21,8 @@ func (d DeviceID) String() string {
        return hex.EncodeToString(d[:displayLen])
 }
 
-func (d *DeviceID) cptr() *C.ma_device_id {
-       return (*C.ma_device_id)(unsafe.Pointer(d))
+func (d *DeviceID) Cptr() unsafe.Pointer {
+       return C.CBytes(d[:])
 }
 
 // DeviceInfo type.

and setting the DeviceConfig struct as follows:

devConf1 := malgo.DeviceConfig {
	DeviceType: malgo.Duplex,
	SampleRate: 44100,
	Capture: malgo.SubConfig{
		DeviceID: infos[0].ID.Cptr(),
		Format: malgo.FormatS16,
		Channels: 1,
	},
	Playback: malgo.SubConfig{
		DeviceID: infos[0].ID.Cptr(),
		Format: malgo.FormatS16,
		Channels: 1,
	},
}

Let me know if this is an OK solution for you - I will create a PR with the changes if it is.

[fbrozovic]

Just realized that the pointer returned by C.CBytes() needs to be freed, but unfortunately the device config is not accessible from Uninit() as far as I can see...

Though I guess that since with the above solution, the user is calling Cptr() on the device ID, they should also be responsible for calling C.free on it. It's a bit ugly though, because of the

// #include <stdlib.h>
import "C"

that's needed in the user application.

[gen2brain]

It should be fixed in 1b98196 , just pass DeviceID: infos[0].ID.Pointer() or whatever index of device.

@fbrozovic No need to free anything in this case, it is not allocated from Go, whatever you allocate in C from Go should be freed.