Codec 2 README

Codec 2 is an open source (LGPL 2.1) low bit rate speech codec: http://rowetel.com/codec2.html

Also included:

• The FreeDV API for digital voice over radio. FreeDV is an open source digital voice protocol that integrates modems, codecs, and FEC README_freedv
• APIs for raw and Ethernet packet data over radio README_data
• High performance coherent OFDM modem for HF channels README_ofdm
• High performance non-coherent FSK modem README_fsk
• An STM32 embedded version of FreeDV 1600/700D for the SM1000
• Coherent PSK modem README_cohpsk for HF channels
• FDMDV DPSK modem README_fdmdv for HF channels

Quickstart

1. Install packages (Debian/Ubuntu):

   sudo apt install git build-essential cmake
   

   Fedora/RH distros:

   sudo dnf groupinstall "Development Tools" "C Development Tools and Libraries"
   sudo dnf install cmake
   

2. Build Codec 2:

   git clone [email protected]:drowe67/codec2.git
   cd codec2
   mkdir build_linux
   cd build_linux
   cmake ..
   make
   

3. Listen to Codec 2 (run from codec2/build_linux):

   ./src/c2demo ../raw/hts1a.raw hts1a_c2.raw
   aplay -f S16_LE ../raw/hts1a.raw
   aplay -f S16_LE hts1a_c2.raw
   

4. Compress, decompress and then play a file using Codec 2 at 2400 bit/s:

   ./src/c2enc 2400 ../raw/hts1a.raw hts1a_c2.bit
   ./src/c2dec 2400 hts1a_c2.bit hts1a_c2_2400.raw 
   

   which can be played with:

   aplay -f S16_LE hts1a_c2_2400.raw
   

   Or using Codec 2 using 700C (700 bits/s):

   ./src/c2enc 700C ../raw/hts1a.raw hts1a_c2.bit
   ./src/c2dec 700C hts1a_c2.bit hts1a_c2_700.raw
   aplay -f S16_LE hts1a_c2_700.raw
   

5. If you prefer a one-liner without saving to files:

   ./src/c2enc 1300 ../raw/hts1a.raw - | ./src/c2dec 1300 - - | aplay -f S16_LE
   

FreeDV 2020 support (building with LPCNet)

1. Build codec2 initially without LPCNet

   cd ~
   git clone https://github.com/drowe67/codec2.git
   cd codec2 && mkdir build_linux && cd build_linux
   cmake ../
   make
   

2. Build LPCNet:

   cd ~
   git clone https://github.com/drowe67/LPCNet
   cd LPCNet && mkdir build_linux && cd build_linux
   cmake -DCODEC2_BUILD_DIR=~/codec2/build_linux ../ 
   make
   

3. (Re)build Codec 2 with LPCNet support:

   cd ~/codec2/build_linux && rm -Rf *
   cmake -DLPCNET_BUILD_DIR=~/LPCNet/build_linux ..
   make
   

Programs

• c2demo encodes a file of speech samples, then decodes them and saves the result.

• c2enc encodes a file of speech samples to a compressed file of encoded bits. c2dec decodes a compressed file of bits to a file of speech samples.

• c2sim is a simulation/development version of Codec 2. It allows selective use of the various Codec 2 algorithms. For example switching phase modelling or quantisation on and off.

• freedv_tx & freedv_rx are command line implementations of the FreeDV protocol, which combines Codec 2, modems, and Forward Error Correction (FEC).

• cohpsk_* are coherent PSK (COHPSK) HF modem command line programs.

• fdmdv_* are differential PSK HF modem command line programs (README_fdmdv).

• fsk_* are command line programs for a non-coherent FSK modem (README_fsk).

• ldpc_* are LDPC encoder/decoder command line programs, based on the CML library.

• ofdm_* are OFDM PSK HF modem command line programs (README_ofdm).

Building and Running Unit Tests

CTest is used as a test framework, with support from GNU Octave scripts.

1. Install GNU Octave and libraries on Ubuntu with:

   sudo apt install octave octave-common octave-signal liboctave-dev gnuplot python3-numpy sox valgrind
   

2. Install CML library with instructions at the top of octave/ldpc.m

3. To build and run the tests:

   cd ~/codec2
   rm -Rf build_linux && mkdir build_linux
   cd build_linux
   cmake -DCMAKE_BUILD_TYPE=Debug ..
   make all test
   

4. To just run tests without rebuilding:

   ctest
   

5. To get a verbose run (e.g. for test debugging):

   ctest -V
   

6. To just run a single test:

   ctest -R test_OFDM_modem_octave_port
   

7. To list the available tests:

   ctest -N
   

Directories

cmake       - cmake support files
misc        - misc C programs that have been useful in development,
              not reqd for Codec 2 release. Part of Debug build.
octave      - Octave scripts used to support development
script      - shell scripts for playing and converting raw files
src         - C source code for Codec 2, FDMDV modem, COHPSK modem, FreeDV API
raw         - speech files in raw format (16 bits signed linear 8 kHz)
stm32       - STM32F4 microcontroller and SM1000 FreeDV Adaptor support
unittest    - Code to perform and support testing. Part of Debug build.
wav         - speech files in wave file format

GDB and Dump Files

1. To compile with debug symbols for using gdb:

   cd ~/codec2
   rm -Rf build_linux && mkdir build_linux
   cd build_linux
   CFLAGS=-g cmake ..
   make
   

2. For dump file support (dump data from c2sim for input to Octave development scripts):

   cd ~/codec2
   rm -Rf build_linux && mkdir build_linux
   cd build_linux
   CFLAGS=-DDUMP cmake ..
   make
   

Building for Windows on a Linux machine

On Ubuntu 17 and above:

sudo apt-get install mingw-w64
mkdir build_windows && cd build_windows
cmake .. -DCMAKE_TOOLCHAIN_FILE=/home/david/freedv-dev/cmake/Toolchain-Ubuntu-mingw32.cmake -DUNITTEST=FALSE -DGENERATE_CODEBOOK=/home/david/codec2/build_linux/src/generate_codebook 
make

Building for Windows on a Windows machine

mkdir build_windows (Or what ever you want to call your build dir)
cmake -G "MinGW Makefiles" -D CMAKE_MAKE_PROGRAM=mingw32-make.exe
Or if you use ninja for building cmake -G "Ninja" ..
mingw32-make or ninja  depends on what you used in the last command
wait for it to build.

Including Codec 2 in an Android project

In an Android Studio 'NDK' project (a project that uses 'native' code) Codec 2 can be added to the project in the following way.

1. Add the Codec 2 source tree to your app (e.g. in app/src/main/codec2) (e.g. as a git sub-module).

2. Add Codec 2 to the CMakeList.txt (app/src/main/cpp/CMakeLists.txt):

   # Sets lib_src_DIR to the path of the target CMake project.
   set( codec2_src_DIR ../codec2/ )
   # Sets lib_build_DIR to the path of the desired output directory.
   set( codec2_build_DIR ../codec2/ )
   file(MAKE_DIRECTORY ${codec2_build_DIR})
   
   add_subdirectory( ${codec2_src_DIR} ${codec2_build_DIR} )
   
   include_directories(
       ${codec2_src_DIR}/src
       ${CMAKE_CURRENT_BINARY_DIR}/../codec2
   )
   

3. Add Codec 2 to the target_link_libraries in the same file.

Building Debian packages

To build Debian packages, simply run the "cpack" command after running "make". This will generate the following packages:

• codec2: Contains the .so and .a files for linking/executing applications dependent on Codec2.

• codec2-dev: Contains the header files for development using Codec2.

Once generated, they can be installed with "dpkg -i" (once LPCNet is installed). If LPCNet is not desired, CMakeLists.txt can be modified to remove that dependency.