OboeTester is an app that can be used to test many of the features of Oboe, AAudio and OpenSL ES.
Download the top level oboe repository from GitHub. Then use Android Studio (3.3 or above) to build the app in this folder.
There are several different tests available from the main module.
Test opening, starting, stopping and closing a stream. Various stream parameters can be selected before opening. While the stream is playing, the frame counts and stream state are displayed. The latency is estimated based on the timestamp information.
Test input streams. Displays current volume as VU bars.
Measure touch screen latency plus audio output latency. Open, Start, then tap on the screen with your fingertip. The app will listen for the sound of your fingernail tapping the screen and the resulting beep, and then measure the time between them. If you use headphones then you can eliminate the latency caused by speaker protection. If you use USB-MIDI input then you can eliminate the latency due to the touch screen, which is around 15-30 msec. MIDI latency is generally under 1 msec.
Record several seconds of audio and play it back. The Share button lets you share the recorded WAV file. You can then examine the WAV file using a program like Audacity.
This test copies input to output and adds up to 3 seconds of delay. This can be used to simulate high latency on a phone that supports low latency. Try putting the phone to your ear with the added delay at 0 and try talking. Then set it to about 100 msec and try talking on the phone. Notice how the echo can be very confusing.
This test requires a loopback adapter. It measures the input and output latency combined. You will probably need to adjust the volume until the echo level is correct.
This test works best with a loopback adapter. But it can also work in a quiet room. It plays a sine wave and then tries to record and lock onto that sine wave. If the actual input does not match the expected sine wave value then it is counted as a glitch. The test will display the maximum time that it ran without seeing a glitch. A “reset” occurs if there is not enough input data, which causes a gap in the signal. Some resets are common at the beginnng.
Measure glitches for various combinations of input and output settings. Change the test duration to a high value and let it run for a while. If you get glitches in one configuration then you can investigate using the Manual Glitch Test. The Share button will let you email the report to yourself.