IssueTracker

Hello,

To test Android 14’s support for multiple USB devices, I installed Android 14 on a Raspberry Pi. My Android 14 image is sourced from the following link: https://konstakang.com/devices/rpi4/AOSP14/.

I found that Android 14 does not support multiple USB devices by default, so I modified the system/build.prop file and added the following line:

ro.audio.multi_usb_mode=true

After rebooting my Raspberry Pi, I performed the following steps:

1. First, I used the command adb shell getprop ro.audio.multi_usb_mode to check the value, and the result was true, as shown in the image below.

D:\pre>adb shell getprop ro.audio.multi_usb_mode
true

2. Second, I used cat /proc/asound/cards to check and confirm that two USB devices were detected.

rpi4:/ # cat /proc/asound/cards
 0 [Headphones     ]: bcm2835_headpho - bcm2835 Headphones
                      bcm2835 Headphones
 1 [vc4hdmi0       ]: vc4-hdmi - vc4-hdmi-0
                      vc4-hdmi-0
 2 [vc4hdmi1       ]: vc4-hdmi - vc4-hdmi-1
                      vc4-hdmi-1
 3 [Set            ]: USB-Audio - C-Media USB Headphone Set
                      C-Media USB Headphone Set at usb-0000:01:00.0-1.2, full speed
 4 [Headset        ]: USB-Audio - Logi USB Headset
                      Logi USB Headset Logi USB Headset at usb-0000:01:00.0-1.3, full speed

3. Finally, I entered my application and used the AudioManager methods to retrieve the device information, but only one USB device was returned. The relevant code and logs are as follows:

private fun getDeviceList(){
    val audioManager= mContext.getSystemService(Context.AUDIO_SERVICE) as AudioManager

    val inputDeviceList=audioManager.getDevices(AudioManager.GET_DEVICES_INPUTS)
    val outputDeviceList=audioManager.getDevices(AudioManager.GET_DEVICES_OUTPUTS)
    Log.i(tag,"The number of audio input devices size is ${inputDeviceList.size}")
    for(inputAudioDeviceInfo in inputDeviceList){
        Log.i(tag,"type:${inputAudioDeviceInfo.type},product name:${inputAudioDeviceInfo.productName}," +
                "isSource:${inputAudioDeviceInfo.isSource},isSink:${inputAudioDeviceInfo.isSink}")
    }

    Log.i(tag,"The number of audio output devices size is ：${outputDeviceList.size}")
    for(outputDevice in outputDeviceList){
        Log.i(tag,"type:${outputDevice.type},product name:${outputDevice.productName}," +
                "isSource:${outputDevice.isSource},isSink:${outputDevice.isSink}")
    }
}

2024-01-04 19:45:52.882  2628-2628  MyApplication           com.test.pjsiptest                   I  The number of audio input devices size is 3
2024-01-04 19:45:52.883  2628-2628  MyApplication           com.test.pjsiptest                   I  type:15,product name:Raspberry Pi 4,isSource:true,isSink:false
2024-01-04 19:45:52.883  2628-2628  MyApplication           com.test.pjsiptest                   I  type:25,product name:Raspberry Pi 4,isSource:true,isSink:false
2024-01-04 19:45:52.883  2628-2628  MyApplication           com.test.pjsiptest                   I  type:22,product name:USB-Audio - Logi USB Headset,isSource:true,isSink:false
2024-01-04 19:45:52.883  2628-2628  MyApplication           com.test.pjsiptest                   I  The number of audio output devices size is ：2
2024-01-04 19:45:52.883  2628-2628  MyApplication           com.test.pjsiptest                   I  type:2,product name:Raspberry Pi 4,isSource:false,isSink:true
2024-01-04 19:45:52.884  2628-2628  MyApplication           com.test.pjsiptest                   I  type:22,product name:USB-Audio - Logi USB Headset,isSource:false,isSink:true

Based on this link: https://source.android.com/docs/core/audio/combined-audio-routing, the documentation mentions that the USB framework supports routing to multiple USB devices, as long as the USB devices have different audio device types.

I checked my two USB headsets, and both have the audio device type TYPE_USB_HEADSET. Is this the reason why my program is only able to recognize one USB headset?

Our current requirement is to use two USB devices on an Android device to handle two simultaneous calls.

If Android 14 must support USB devices with different device types, how can I implement my functionality?

Can I achieve this by modifying the USB audio device’s device descriptor, or by modifying the audio device type of the USB headset in the Android audio HAL layer, such as directly modifying the UsbAlsaManager class? If so, this would allow Android 14 to support both of my USB headsets.

I have been waiting for this feature since Android 11, and now I’m testing with Android 14. Please find the detailed bug report attached.

I am eagerly awaiting your response.