Several
Android Compatibility Test Suite
(CTS)
tests for
Android USB audio
require the physical connection of USB audio
peripherals. For these, additional CTS Verifier tests have been implemented.
Nomenclature
Throughout this document, the term "device" and "peripheral" are used in a
very precise manner:
- Device
refers to the Android device.
- Peripheral
refers to an external USB audio peripheral
connected to the Android device.
Supported Peripherals
Please use the peripherals listed below for the USB audio CTS Verifier Tests.
USB audio interface
One of these peripherals is required to conduct the USB Audio Peripheral
Attributes test. They can also be used for the Play test and Record test.
A USB audio interface (A PreSonus AudioBox 96).
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USB headset
For the CTS Verifier
USB Audio Loopback Tests
we strongly recommend using the
Google USB-C
digital to 3.5 mm headphone adapter
. We have found that many other adapters
add significant latency. Some also add echo cancellation, which can block the loopback signal.
The CTS Verifier
USB Audio Buttons Test
does not require a specific USB
headset peripheral. It can be any of the following:
Note that in either case, the button must produce virtual key codes for all three of the
required buttons (volume up, volume down, play/pause) for the test to succeed.
Refer to the Software mapping section in
Android USB Headset Accessory Specification
for the virtual key codes.
A USB headset.
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Required additional hardware
Patch cables (for loopback) 2 short ¼" male to ¼" male patch cables to
connect the outputs to the inputs of the USB
¼" male to ¼" male patch cables.
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USB peripheral cable
This cable (which typically comes with the peripheral),
connects the USB audio peripheral to the host device.
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USB "On The Go" (OTG) adapter
A USB "On The Go" (OTG) adapter is required to physically
connect the peripheral to the Android device and indicate to the Android
device that it should assume the role of "host".
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Analog headphones to monitor the output of the USB audio interface for the
Play test.
Set of analog headphones.
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Tests
In each test, indicate test success by clicking the
test
pass
(check mark) button. Otherwise, indicate test failure by
clicking the
test fail
(exclamation point) button.
Attributes test
Abstract
This test verifies that the attributes (supported sample-rates, channel
configurations, sample formats, etc.) match the set of a-priori known attributes
of the device.
Process
After invoking the test from the main menu, connect a USB audio
peripheral. If the attributes match, the
test pass
(check
mark) button will be enabled.
Select
USB Audio Peripheral Attributes
Test.
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Summary of instructions is displayed.
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Pre-connect screen.
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USB audio peripheral connected to Android Device with
peripheral cable and OTG adapter.
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Post-connect screen.
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Play test
Abstract
This test verifies that audio playback is functioning. It does this by
generating a 1KHz test tone and presenting it in stereo (two-channels) to the
USB audio peripheral.
Process
After invoking the test from the main menu, connect the USB audio
interface, including the analog headset, to the headset output jack on the
interface for monitoring.
Press the
PLAY
button. If the test tone is heard in both
channels of the headset, indicate test pass by clicking the
test
pass
(check mark) button. If either or both of the channels do not
play the tone, indicate test failure by clicking the
test
fail
(exclamation point) button.
Notes
Record (loopback) test
Abstract
This test verifies that audio recording is functioning. It does this by
generating a tone at the outputs of the USB audio interface, which is then
routed via patch cords to the inputs of the USB audio peripheral.
Process
After invoking the test from the main menu, connect the USB audio
interface. Connect the analog outputs to the analog inputs with patch cables.
Press the
RECORD LOOPBACK
button. If both the channels of
the recorded test tone are shown in the view below, indicate test pass by
clicking the
test pass
(check mark) button. If either or
both of the channels does not display, indicate test failure by clicking the
test fail
(exclamation point) button.
Notes
Ensure positive connection of both input and output jacks on the
peripheral. It will be necessary to adjust the input levels to correctly
display the recorded signal.
Select
USB Audio Peripheral Record Test.
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Summary of instructions is displayed.
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Pre-connect screen.
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USB audio Interface with loopback connected to Android
device.
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Connections on the back of the USB audio interface.
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Connections on the front of the USB audio interface.
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Post-connect screen.
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Post-connect screen, with record test running.
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Abstract
This test verifies the
media/transport
buttons on the
recommended headset are correctly recognized.
Process
After invoking the test from the main menu, connect the USB headset
peripheral. Press each
media/transport
(play, pause, volume
up & volume down) button on the headset. As each is recognized, it will be
recognized in the test panel. When all buttons have been recognized, the
test pass
(check mark) button will be enabled. Click the
test pass
button to indicate success. If the full set of
buttons is not recognized, indicate test failure by clicking the
test
fail
(exclamation point) button.
Notes