mirror of
https://git.eden-emu.dev/eden-emu/eden.git
synced 2025-10-26 12:33:22 +00:00
67 lines
3.1 KiB
Markdown
67 lines
3.1 KiB
Markdown
**DrumThumper**
|
|
==========
|
|
Oboe playback sample app.
|
|
|
|
## Abstract
|
|
**DrumThumper** is a "Drum Pad" app which demonstrates best-practices for low-latency audio playback using the Android **Oboe** API.
|
|
**DrumThumper** consists of a set of trigger pad widgets and an optional UI for controlling the level and stereo placement of each of the virtual drums.
|
|
The audio samples are stored in application resources as WAV data. This is parsed and loaded (by routines in **parselib**) into memory blocks.
|
|
The audio samples are mixed and played by routines in **iolib**.
|
|
|
|
**DrumThumper** is written in a combination of Kotlin for the UI and JNI/C++ for the player components (to demonstrate accessing native code from a Kotlin or Java application).
|
|
|
|
## Scope
|
|
**DrumThumper** is designed with the following goals in mind:
|
|
* To demonstrate the most efficient means of playing audio with the lowest possible latency.
|
|
* To demonstrate how to play multiple sources of audio mixed into a single Oboe stream.
|
|
* To demonstrate the life-cycle of an Oboe audio stream and it's relationship to the application lifecycle.
|
|
* To demonstrate the correct handling of playback errors and output device connection/disconnection.
|
|
|
|
Secondarily, **DrumThumper** demonstrates:
|
|
* Using Android "assets" for audio data.
|
|
* The mechanism for calling native (C/C++) audio functionality from a Kotlin/Java app.
|
|
* A mechanism for sharing binary data between a Kotlin/Java app with the native (C/C++) layer.
|
|
* A mechanism for parsing/loading one type (WAV) of audio data.
|
|
* How to control the relative levels (gain) of audio sources mixed into an output stream.
|
|
* How to locate a mono data source in a stereo output stream.
|
|
* How to use the Oboe resampler to resample source audio to the device playback rate, and therefore not incur this overhead at playback time.
|
|
|
|
To keep things simple, **DrumThumper** specifically does not:
|
|
* Does not support audio samples in other than 16-bit PCM Samples. It does not support different PCM formats.
|
|
* Does not support non-WAV audio data (such as AIFF).
|
|
* Does not support compressed audio data.
|
|
|
|
**DrumThumper** now supports different sample rates for the source samples.
|
|
|
|
**DrumThumper** now supports mono and stereo sources.
|
|
|
|
## DrumThumper project structure
|
|
### Kotlin App Layer
|
|
Contains classes for the application logic and defines the methods for accessing the native data and player functionality.
|
|
|
|
### Native (C++) layer
|
|
Contains the implementation of the `native` (JNI) methods defined in the `DrumPlayer` (Kotlin) class.
|
|
|
|
### Dependent Libraries
|
|
* **iolib**
|
|
Classes for playing audio data.
|
|
|
|
* **parselib**
|
|
Classes for parsing and loading audio data from WAV resources.
|
|
|
|
## App
|
|
* DrumPlayer.kt
|
|
The Kotlin class which provides the audio playback functionality by interfacing with the native (C++) libraries.
|
|
|
|
* DrumThumperActivity.kt
|
|
The main application logic.
|
|
|
|
* TriggerPad.kt
|
|
An Android View subclass which implements the "trigger pad" UI widgets
|
|
|
|
## Native-interface (JNI)
|
|
* DrumPlayerJNI.cpp
|
|
This is where all the access to the native functionality is implemented.
|
|
|
|
## Screenshots
|
|
|