This project is for research purposes only. Without a proper license private and commercial usage might be a case of a patent infringement. If you are looking for a library, which can be installed and used legally (commercial, private and educational usage), go to the Qualcomm® aptX™ homepage and contact Qualcomm customer service.
The source code itself is licensed under the terms of the MIT license. However, compression algorithms are patented and licensed under the terms of a proprietary license. Hence, compilation and redistribution in a binary format is forbidden!
mkdir build && cd build
cmake -DENABLE_DOC=ON -DWITH_FFMPEG=ON -DWITH_SNDFILE=ON ..
make && make installENABLE_DOC- build and install manual files (requires Doxygen)ENABLE_APTX_DECODER_API- build with apt-X / apt-X HD decoder API (default: ON)ENABLE_APTX_ENCODER_API- build with apt-X / apt-X HD encoder API (default: ON)ENABLE_APTX422- build reverse engineered apt-X library based onbt-aptX-x86-4.2.2.soENABLE_APTXHD100- build reverse engineered apt-X HD library based onaptXHD-1.0.0-ARMv7AWITH_FFMPEG- use FFmpeg as a back-end (otherwise, stub library will be built)WITH_SNDFILE- read file formats supported by libsndfile (used by openaptx utils)
In the apt-X stub library (build without FFmpeg back-end), all symbols are exported as
weak. As a consequence, it should be possible to
overwrite them during runtime with other library which exports strong symbols. However, it might
be required to define LD_DYNAMIC_WEAK environment variable - for more information consult
ld.so manual.
When reverse-engineered libraries were enabled, they will be automatically linked with the apt-X stub library (build without FFmpeg back-end). See previous paragraph for the meaning of this.
Below is the result of a small benchmark test performed with various apt-X encoding libraries.
Test was done with the usage of aptxenc and aptxhdenc tools from this repository.
Elapsed user time was calculated with the usage of a standard UNIX time command line tool. All
libraries (except original Qualcomm libraries) were compiled with Clang version 8.0.7 with the
O2 or O3 optimization level.
- CPU: ARM Cortex-A53
- Input file: WAV audio, Microsoft PCM, 16 bit, stereo 48000 Hz
- Input duration: 15 minutes 45 seconds
| Library | apt-X | Mbit/s | apt-X HD | Mbit/s |
|---|---|---|---|---|
| libaptX-1.0.16-rel-Android21 | 1m00.370s | 1.23673 | — | — |
| libaptXHD-1.0.1-rel-Android21 | — | — | 1m07.030s | 1.11109 |
| openaptx-stub | 0m04.480s | 0.0 | 0m04.820s | 0.0 |
| openaptx-ffmpeg (libavcodec-58.54.100) | 1m58.100s | 0.60835 | 2m03.270s | 0.58354 |
| aptx422 | 1m19.840s | 0.91721 | — | — |
| aptxHD100 | — | — | 1m21.950s | 0.89616 |
| libopenaptx-0.2.0 | 1m22.090s | 0.89062 | 1m25.730s | 0.85429 |