The SBC codec is the mandotory codec for Bluetooth audio over A2DP Profile
The technical specification of the codec is covered in Appendix B of Advanced Audio Distribution
mSBC extension is covered by Appendix A of Hands-Free Profile
The directory layout is as follows :
- include: Library interface
- src: Source files
- tools: Standalone encoder/decoder tools
- build: Building outputs
- bin: Compilation output
The default toolchain used is GCC. Invoke make to build the library.
$ make -jCompiled library libsbc.a will be found in bin directory.
The cc, as, ld and ar can be selected with respective Makefile variables CC,
AS, LD and AR. The AS and LD selections are optionnal, and fallback
to CC selection when not defined.
$ make -j CC=path_to_toolchain/bin/toolchain-prefix-gcc CFLAGS="..."Compiled library will be found in bin directory.
Assembly code is available for armv7-em architecture. Enabling assembly code
is done with the ARCH Makefile variable. Following example enable assembly
optimization for target CPU ARM Cortex M4 :
$ make -j CC=path_to_arm_toolchain/bin/toolchain-prefix-gcc \
CFLAGS="-mcpu=cortex-m4 -mthumb" ARCH="arm-v7em"Tools can be all compiled, while involking make as follows :
$ make toolsThe standalone encoder esbc take a wave file as input and encode it
according given parameter. The standalone decoder dsbc do the inverse
operation.
Refer to esbc -h or dsbc -h for options.
Note that esbc output bitstream to standard output when output file is
omitted. On the other side dsbc read from standard input when input output
file are omitted.
In such way you can easly test encoding / decoding loop with :
$ ./esbc <in.wav> -b <bitpool> | ./dsbc > <out.wav>Adding Linux aplay tools, you are able to instant hear the result :
$ ./esbc <in.wav> -b <bitpool> | ./dsbc | aplay