libbw64 – ITU-R BS.2088 Library

Introduction

The libbw64 library is a lightweight C++ header only library to read and write BW64 files. BW64 is standardised as Recommendation ITU-R BS.2088 and the successor of RF64. So it already contains necessary extensions to support files which are bigger than 4 GB. Apart from that a BW64 file is able to contain the ADM metadata and link it with the audio tracks in the file. To do that a BW64 file specifies two new RIFF chunks – the axml chunk and the chna chunk. To parse, create, modify and write the ADM metadata in the axml chunk you may use the libadm library.

Read the documentation to get started.

Features

• no dependencies
• support file sizes bigger than 4 GB (ds64 chunk)
• read and write axml and chna chunks
• 16, 24, and 32 bit integer file formats

Installation

macOS

On macOS you can use homebrew to install the library. You just have to add the EBU NGA homebrew tap and can then use the usual install command.

brew tap ebu/homebrew-nga
brew install libbw64

Manual installation

To manually install the library you have to clone the git repository and then use the CMake (version 3.5 or later) build system to build and install it.

git clone git@github.com:ebu/libbw64.git
cd libbw64
mkdir build && cd build
cmake ..
make
make install

Copy headers

The libbw64 is a header-only library so installing the library is not by all means necessary. It is also possible to just copy the content of the include directory to your project and make sure to add the bw64 folder to your PATH, that the header files can be found by the compiler.

CMake

As the library uses CMake as a build system it is really easy to set up and use if your project does too. Assuming you have installed the library, the following code shows a complete CMake example to compile a program which uses the libbw64.

cmake_minimum_required(VERSION 3.5)
project(libbw64_example VERSION 1.0.0 LANGUAGES CXX)

find_package(bw64 REQUIRED)

add_executable(example example.cpp)
target_link_libraries(example PRIVATE bw64)

If you prefer not to install the library on your system you can also use the library as a subproject. You can just add the library as a CMake subproject. Just add the folder containing the repository to your project and you can use the bw64 target.

cmake_minimum_required(VERSION 3.5)
project(libbw64_example VERSION 1.0.0 LANGUAGES CXX)

add_subdirectory(submodules/libbw64)

add_executable(example example.cpp)
target_link_libraries(example PRIVATE bw64)

Note

If libbw64 is used as a CMake subproject the default values of the options

• BW64_UNIT_TESTS
• BW64_EXAMPLES
• BW64_PACKAGE_AND_INSTALL

are automatically set to FALSE.

Basic usage

To use libbw64 simply include the main header file bw64.hpp and use the functions bw64::readFile and bw64::writeFile to create a BW64Reader or BW64Writer object. The functions return a unique_ptr to the object.

Read a BW64 file

#include <iostream>
#include <vector>
#include <bw64/bw64.hpp>

const unsigned int BLOCK_SIZE = 4096;

int main(int argc, char const* argv[]) {
  if (argc != 2) {
    std::cout << "usage: " << argv[0] << " [INFILE]" << std::endl;
    exit(1);
  }
  auto inFile = bw64::readFile(argv[1]);
  auto axmlChunk = inFile->axmlChunk();  // get axml chunk
  auto chnaChunk = inFile->chnaChunk();  // get chna chunk
  std::vector<float> buffer(BLOCK_SIZE * inFile->channels());
  while (!inFile->eof()) {
    auto readFrames = inFile->read(&buffer[0], BLOCK_SIZE);
    // TODO: process samples
  }
  return 0;
}

Write a BW64 file

#include <iostream>
#include <vector>
#include <bw64/bw64.hpp>

const unsigned int BLOCK_SIZE = 4096;

int main(int argc, char const* argv[]) {
  if (argc != 2) {
    std::cout << "usage: " << argv[0] << " [OUTFILE]" << std::endl;
    exit(1);
  }
  auto outFile = bw64::writeFile(argv[1]);
  std::vector<float> buffer(BLOCK_SIZE);
  for (int i = 0; i < 100; ++i) {
    // TODO: fill vector with data
    outFile->write(&buffer.front(), BLOCK_SIZE);
  }
  return 0;
}

More examples

See the examples folder in the repository for more examples.

Credits

libbw64 is originally a development of the IRT.

Acknowledgement

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 687645.

License

Copyright 2018-2020 The libbw64 Authors

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.