jna-aac-encoder

This library provides AAC encoding capabilities for the JVM. It utilizes the FDK AAC library via JNA in order to do so.

License

Important! While this library uses LGPL-3, please see the FDK AAC license for additional information regarding re/distribution and licensing limitations.

Usage

Dependencies

Artifacts are available on maven central:

Maven

<dependency>
    <groupId>org.sheinbergon</groupId>
    <artifactId>jna-aac-encoder</artifactId>
    <version>0.1.6</version>
</dependency>

Gradle

compile 'org.sheinbergon:jna-aac-encoder:0.1.6'

Additional information

• Single artifact containing libfdk-aac shared libraries cross-compiled for:
  • Linux (64-bit)
  • Windows (32-bit and 64-bit)
  • OSX (64-bit, compiled with Xcode 9.4.1 SDK)
• Provided fdk-aac version is 0.1.6
• Both versions 0.1.6 and 0.1.6 were tested and found to comply with this bridge.

Encoding using the JVM AudioSystem

AudioInputStream input = AudioSystem.getAudioInputStream(...);
File output = new File(...);
AudioSystem.write(input, AACFileTypes.AAC_LC, output);

Performance

Performance benchmarks comparing JNA to a BINARY application(aac-enc) are available using JMH and JMH Visualizer:

To run the benchmarks locally:

• Clone this repository onto a Linux host
• Ensure that you have libfdk-aac.so library installed (either from an external repository or manually compiled)
• Ensure that you have the aac-enc binary installed (either from an external repository or manually compiled)
• Run the following command (from within the cloned repository)

./gradlew -b benchmark.gradle jmh jmhReport

• If the aac-enc binary is not installed in /usr/bin/aac-enc, you can a custom path path by adding this gradle property:

-PaacEncBin=/CUSTOM/PATH/TO/AAC-ENC 

• The JMH reports can be viewed by opening build/reports/benchmark/index.html in your browser.

Limitations

Currently, libfdk-aac itself supports only the pcm_s16le WAV input format, meaning:

• Sample size - 16 bit(signed)
• WAV format - (L)PCM
• Byte order - Little Endian

While this form of input formatting seems to be the common raw-audio formatting, it's important to note that providing input audio with different formatting will cause the encoding process to fail.

Additional restrictions:

• A maximum of 6 audio input/output channels
• Only the AAC-LC/HE-AAC/HE-AACv2 encoding profiles are supported

Roadmap

• Upgrade to fdk-aac 2.0.x
• Improved lower-level interface (with examples).
• Support for 24 bit WAV input (via conversion).
• M4A encoding.
• AAC decoding ???