The NeXT/Sun audio file format.
Sample files:
This page hosts a formal specification of AU audio format using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for C++11/STL generated by Kaitai Struct depends on the C++/STL runtime library. You have to install it before you can parse data.
For C++, the easiest way is to clone the runtime library sources and build them along with your project.
Using Kaitai Struct in C++/STL usually consists of 3 steps.
std::istream). One can open local file for that, or use existing std::string or char* buffer.
#include <fstream>
std::ifstream is("path/to/local/file.au", std::ifstream::binary);
#include <sstream>
std::istringstream is(str);
#include <sstream>
const char buf[] = { ... };
std::string str(buf, sizeof buf);
std::istringstream is(str);
#include "kaitai/kaitaistream.h"
kaitai::kstream ks(&is);
au_t data(&ks);
After that, one can get various attributes from the structure by invoking getter methods like:
data.magic() // => get magic
#pragma once
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
#include "kaitai/kaitaistruct.h"
#include <stdint.h>
#include <memory>
#if KAITAI_STRUCT_VERSION < 9000L
#error "Incompatible Kaitai Struct C++/STL API: version 0.9 or later is required"
#endif
/**
* The NeXT/Sun audio file format.
*
* Sample files:
*
* * <https://github.com/python/cpython/tree/b8a7daf077da/Lib/test/sndhdrdata>
* * <ftp://ftp-ccrma.stanford.edu/pub/Lisp/sf.tar.gz>
* * <https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/AU/Samples.html>
* \sa https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/AU/AU.html Source
* \sa http://soundfile.sapp.org/doc/NextFormat/ Source
* \sa http://soundfile.sapp.org/doc/NextFormat/soundstruct.h Source
* \sa https://github.com/andreiw/polaris/blob/deb47cb/usr/src/head/audio/au.h#L87-L112 Source
* \sa https://github.com/libsndfile/libsndfile/blob/86c9f9eb/src/au.c#L39-L74 Source
* \sa https://github.com/chirlu/sox/blob/dd8b63bd/src/au.c#L34-L49 Source
* \sa https://github.com/mpruett/audiofile/blob/b62c902/libaudiofile/NeXT.cpp#L65-L96 Source
*/
class au_t : public kaitai::kstruct {
public:
class header_t;
enum encodings_t {
ENCODINGS_MULAW_8 = 1,
ENCODINGS_LINEAR_8 = 2,
ENCODINGS_LINEAR_16 = 3,
ENCODINGS_LINEAR_24 = 4,
ENCODINGS_LINEAR_32 = 5,
ENCODINGS_FLOAT = 6,
ENCODINGS_DOUBLE = 7,
ENCODINGS_FRAGMENTED = 8,
ENCODINGS_NESTED = 9,
ENCODINGS_DSP_CORE = 10,
ENCODINGS_FIXED_POINT_8 = 11,
ENCODINGS_FIXED_POINT_16 = 12,
ENCODINGS_FIXED_POINT_24 = 13,
ENCODINGS_FIXED_POINT_32 = 14,
ENCODINGS_DISPLAY = 16,
ENCODINGS_MULAW_SQUELCH = 17,
ENCODINGS_EMPHASIZED = 18,
ENCODINGS_COMPRESSED = 19,
ENCODINGS_COMPRESSED_EMPHASIZED = 20,
ENCODINGS_DSP_COMMANDS = 21,
ENCODINGS_DSP_COMMANDS_SAMPLES = 22,
ENCODINGS_ADPCM_G721 = 23,
ENCODINGS_ADPCM_G722 = 24,
ENCODINGS_ADPCM_G723_3 = 25,
ENCODINGS_ADPCM_G723_5 = 26,
ENCODINGS_ALAW_8 = 27,
ENCODINGS_AES = 28,
ENCODINGS_DELTA_MULAW_8 = 29
};
au_t(kaitai::kstream* p__io, kaitai::kstruct* p__parent = nullptr, au_t* p__root = nullptr);
private:
void _read();
void _clean_up();
public:
~au_t();
class header_t : public kaitai::kstruct {
public:
header_t(kaitai::kstream* p__io, au_t* p__parent = nullptr, au_t* p__root = nullptr);
private:
void _read();
void _clean_up();
public:
~header_t();
private:
uint32_t m_data_size;
encodings_t m_encoding;
uint32_t m_sample_rate;
uint32_t m_num_channels;
std::string m_comment;
au_t* m__root;
au_t* m__parent;
public:
/**
* don't read this field, access `_root.len_data` instead
*
* value `0xffff_ffff` means unspecified size
*/
uint32_t data_size() const { return m_data_size; }
encodings_t encoding() const { return m_encoding; }
uint32_t sample_rate() const { return m_sample_rate; }
/**
* number of interleaved channels
*/
uint32_t num_channels() const { return m_num_channels; }
/**
* Most resources claim that this field must be at least 4 bytes long.
* However, most programs don't enforce it, and [Audacity](
* https://www.audacityteam.org/) even generates .au files with this field
* being 0-byte long. According to <https://nixdoc.net/man-pages/IRIX/man4/dmedia/next.4.html>,
* "NeXT files require that this chunk be at least 4 bytes (chars) long,
* whereas this chunk may be zerolength in a Sun .au file."
*
* By convention, size should be a multiple of 4 -
* see <https://github.com/chirlu/sox/blob/dd8b63bd/src/au.c#L132-L133>.
* Page <http://soundfile.sapp.org/doc/NextFormat/> also mentions that for some
* sound playing programs, this field must have an even byte size. So a multiple
* of 4 is probably best for compatibility.
*
* Must be null-terminated. It is usually an ASCII text string, but this space
* might be also used to store application-specific binary (i.e. non-ASCII) data.
*/
std::string comment() const { return m_comment; }
au_t* _root() const { return m__root; }
au_t* _parent() const { return m__parent; }
};
private:
bool f_len_data;
int32_t m_len_data;
public:
int32_t len_data();
private:
std::string m_magic;
uint32_t m_ofs_data;
std::unique_ptr<header_t> m_header;
au_t* m__root;
kaitai::kstruct* m__parent;
std::string m__raw_header;
std::unique_ptr<kaitai::kstream> m__io__raw_header;
public:
std::string magic() const { return m_magic; }
uint32_t ofs_data() const { return m_ofs_data; }
header_t* header() const { return m_header.get(); }
au_t* _root() const { return m__root; }
kaitai::kstruct* _parent() const { return m__parent; }
std::string _raw_header() const { return m__raw_header; }
kaitai::kstream* _io__raw_header() const { return m__io__raw_header.get(); }
};
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
#include "au.h"
#include "kaitai/exceptions.h"
au_t::au_t(kaitai::kstream* p__io, kaitai::kstruct* p__parent, au_t* p__root) : kaitai::kstruct(p__io) {
m__parent = p__parent;
m__root = this;
m_header = nullptr;
m__io__raw_header = nullptr;
f_len_data = false;
_read();
}
void au_t::_read() {
m_magic = m__io->read_bytes(4);
if (!(magic() == std::string("\x2E\x73\x6E\x64", 4))) {
throw kaitai::validation_not_equal_error<std::string>(std::string("\x2E\x73\x6E\x64", 4), magic(), _io(), std::string("/seq/0"));
}
m_ofs_data = m__io->read_u4be();
m__raw_header = m__io->read_bytes(((ofs_data() - 4) - 4));
m__io__raw_header = std::unique_ptr<kaitai::kstream>(new kaitai::kstream(m__raw_header));
m_header = std::unique_ptr<header_t>(new header_t(m__io__raw_header.get(), this, m__root));
}
au_t::~au_t() {
_clean_up();
}
void au_t::_clean_up() {
}
au_t::header_t::header_t(kaitai::kstream* p__io, au_t* p__parent, au_t* p__root) : kaitai::kstruct(p__io) {
m__parent = p__parent;
m__root = p__root;
_read();
}
void au_t::header_t::_read() {
m_data_size = m__io->read_u4be();
m_encoding = static_cast<au_t::encodings_t>(m__io->read_u4be());
m_sample_rate = m__io->read_u4be();
m_num_channels = m__io->read_u4be();
if (!(num_channels() >= 1)) {
throw kaitai::validation_less_than_error<uint32_t>(1, num_channels(), _io(), std::string("/types/header/seq/3"));
}
m_comment = kaitai::kstream::bytes_to_str(kaitai::kstream::bytes_terminate(m__io->read_bytes_full(), 0, false), std::string("ASCII"));
}
au_t::header_t::~header_t() {
_clean_up();
}
void au_t::header_t::_clean_up() {
}
int32_t au_t::len_data() {
if (f_len_data)
return m_len_data;
m_len_data = ((header()->data_size() == 4294967295UL) ? ((_io()->size() - ofs_data())) : (header()->data_size()));
f_len_data = true;
return m_len_data;
}