| Mega Drone |
| ========== |
| Ever wondered what 100 square waves sound like when played together? Well now you can find out! |
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| Mega Drone is an app which creates 100 oscillators, combines their output in a mixer and plays the resulting sound. |
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| This sample demonstrates how to obtain the lowest latency and optimal computational throughput by: |
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| 1) Leaving Oboe to choose the best default stream properties for the current device |
| 2) Setting performance mode to LowLatency |
| 3) Setting sharing mode to Exclusive |
| 4) Setting the buffer size to 2 bursts |
| 5) Using the `-Ofast` compiler optimization flag, even when building the `Debug` variant |
| 6) Using [`getExclusiveCores`](https://developer.android.com/reference/android/os/Process#getExclusiveCores()) (API 24+) and thread affinity to bind the audio thread to the best available CPU core(s) |
| 7) Using a `StabilizedCallback` which aims to spend a fixed percentage of the callback time to avoid CPU frequency scaling ([video explanation](https://www.youtube.com/watch?v=C0BPXZIvG-Q&feature=youtu.be&t=1158)) |
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| This code was presented at [AES Milan](http://www.aes.org/events/144/) and [Droidcon Berlin](https://www.de.droidcon.com/) as part of a talk on Oboe. |
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| The [following article explaining how to debug CPU performance problems](https://medium.com/@donturner/debugging-audio-glitches-on-android-ed10782f9c64) may also be useful when looking at this code. |
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| Implementation details |
| --- |
| The stream properties are left to Oboe as such the app must output audio data in a format which matches that of the stream. |
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| Four different formats are supported: |
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| |Channel count|Format| |
| |-------------|------| |
| |1 - Mono|16-bit int| |
| |2 - Stereo|16-bit int| |
| |1 - Mono|Float| |
| |1 - Stereo|Float| |
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| The signal chain for mono streams is: |
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| Oscillators->Mixer |
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| For stereo chains a mono to stereo converter is added to the end of the chain: |
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| Oscillators->Mixer->MonoToStereo |
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| The compiler optimization flag `-Ofast` can be found in [CMakeLists.txt](CMakeLists.txt). |
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| Screenshots |
| ----------- |
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