arkq / openaptx

Reverse-engineered apt-X audio codec

[open]aptx - reverse-engineered apt-X

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!

Compilation

mkdir build && cd build
cmake -DENABLE_DOC=ON -DWITH_FFMPEG=ON -DWITH_SNDFILE=ON ..
make && make install

Configure options

• ENABLE_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 on bt-aptX-x86-4.2.2.so
• ENABLE_APTXHD100 - build reverse engineered apt-X HD library based on aptXHD-1.0.0-ARMv7A
• WITH_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.

Benchmark

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.

Setup

• CPU: ARM Cortex-A53
• Input file: WAV audio, Microsoft PCM, 16 bit, stereo 48000 Hz
• Input duration: 15 minutes 45 seconds

Results

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

Resources

1. AptX audio codec family
2. Method and apparatus for electrical signal coding
3. Two-channel QMF bank

openaptx's Issues

AptX Adaptive support #2

Following up #1 to track aptX Adaptive support.

Is configure missing? Don't know how to make it.

cmake -DENABLE_DOC=ON -DWITH_FFMPEG=ON -DWITH_SNDFILE=ON -DENABLE_APTX422=ON -DENABLE_APTXHD100=ON ..
CMake Warning at CMakeLists.txt:22 (message):
Building apt-X / apt-X HD with FFmpeg: Compiling openaptx with FFmpeg as an
encoding backend requires apt-X Adaptive API support in the client code.
Otherwise, client will not be able to free resources allocated with the
aptxbtenc_init() function.

CMake Error at src/CMakeLists.txt:24 (install):
install TARGETS given no LIBRARY DESTINATION for shared library target
"aptx-4.2.2".

CMake Error at src/CMakeLists.txt:38 (install):
install TARGETS given no LIBRARY DESTINATION for shared library target
"aptxHD-1.0.0".

CMake Error at src/CMakeLists.txt:89 (install):
install TARGETS given no LIBRARY DESTINATION for shared library target
"aptx".

CMake Error at utils/CMakeLists.txt:25 (install):
install TARGETS given no RUNTIME DESTINATION for executable target
"aptxdec".

-- Configuring incomplete, errors occurred!
See also "/home/pi/openaptx/build/CMakeFiles/CMakeOutput.log".

Bluealsa crash when using aptX

When running mplayer with multiple files with a set of headphones supporting AptX, bluealsa crashes when mplayer switches files. Investigation led to attempting to free the same memory twice: in file aptx-ffmpeg.c line 137 from the openaptx project,
encoder_ctx_free is called; in a2dp-audio.c, a thread cleanup handler is also freeing the context. This double free causes bluealsa to crash. I removed the thread cleanup handler call from a2dp-audio.c, and this fixes the crash. Here's a link to a patch.

a2dp-audio.c.patch.txt

can't install

No package 'bluez' found <- https://github.com/Arkq/bluez-alsa <- trying to install that <- heres the problem -> bluez is already the newest version (5.50-1+rpt1).

How can I install this over my existing installation and use it

Decode very slow on Raspberry Pi Zero

I compiled from source using the WITH_FFMPEG backend. Playback is not possible, decode speed is lower than realtime. Using AAC I get 13% CPU usage.

Is this a problem in ffmpeg? Not sure where to raise this issue.

AptX Adaptive support

Is it supported already?

Same Header Name

Unless I missed a configuration option, it appears that your header and libopenaptx's are both openaptx.h. Obviously, this means that one cannot have both packages installed simultaneously.

Synchronization errors

Hi @arkq , I'm testing openaptx with bluealsa on raspios.
I have some issues using with a Samsung A5 (2017) connected via bluetooth, forcing it to use aptx coded, but I don't think it is related on the device itself.
I get a plethora of errors on syslog getting the audio streams choppy and unusable.

Those are the errors:
Jan 24 11:33:10 moode bluealsa[20368]: [aptx @ 0x3bd000] Synchronization error
Jan 24 11:33:10 moode bluealsa[20368]: openaptx: ffmpeg apt-X: Send packet failed: Invalid data found when processing input
Jan 24 11:33:10 moode bluealsa[20368]: /usr/bin/bluealsa: E: Apt-X decoding error: Communication error on send

openaptx is built with those flags:
-DENABLE_DOC=ON -DENABLE_APTX422=ON -DENABLE_APTXHD100=ON -DWITH_FFMPEG=ON -DWITH_SNDFILE=ON

I had to add libavutil>=56.22.100 dependency in CMakeFiles to complete the build.
Thank you for the effort you are putting in your projects.