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# generated by Kaitai Struct depends on the C# runtime library. You have to install it before you can parse data.
The C# runtime library is available in the NuGet Gallery. Installation instructions can also be found there.
Parse a local file and get structure in memory:
var data = Au.FromFile("path/to/local/file.au");
Or parse structure from a byte array:
byte[] someArray = new byte[] { ... };
var data = new Au(new KaitaiStream(someArray));
After that, one can get various attributes from the structure by accessing properties like:
data.Magic // => get magic
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
namespace Kaitai
{
/// <summary>
/// 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>
/// </summary>
/// <remarks>
/// Reference: <a href="https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/AU/AU.html">Source</a>
/// </remarks>
/// <remarks>
/// Reference: <a href="http://soundfile.sapp.org/doc/NextFormat/">Source</a>
/// </remarks>
/// <remarks>
/// Reference: <a href="http://soundfile.sapp.org/doc/NextFormat/soundstruct.h">Source</a>
/// </remarks>
/// <remarks>
/// Reference: <a href="https://github.com/andreiw/polaris/blob/deb47cb/usr/src/head/audio/au.h#L87-L112">Source</a>
/// </remarks>
/// <remarks>
/// Reference: <a href="https://github.com/libsndfile/libsndfile/blob/86c9f9eb/src/au.c#L39-L74">Source</a>
/// </remarks>
/// <remarks>
/// Reference: <a href="https://github.com/chirlu/sox/blob/dd8b63bd/src/au.c#L34-L49">Source</a>
/// </remarks>
/// <remarks>
/// Reference: <a href="https://github.com/mpruett/audiofile/blob/b62c902/libaudiofile/NeXT.cpp#L65-L96">Source</a>
/// </remarks>
public partial class Au : KaitaiStruct
{
public static Au FromFile(string fileName)
{
return new Au(new KaitaiStream(fileName));
}
public enum Encodings
{
Mulaw8 = 1,
Linear8 = 2,
Linear16 = 3,
Linear24 = 4,
Linear32 = 5,
Float = 6,
Double = 7,
Fragmented = 8,
Nested = 9,
DspCore = 10,
FixedPoint8 = 11,
FixedPoint16 = 12,
FixedPoint24 = 13,
FixedPoint32 = 14,
Display = 16,
MulawSquelch = 17,
Emphasized = 18,
Compressed = 19,
CompressedEmphasized = 20,
DspCommands = 21,
DspCommandsSamples = 22,
AdpcmG721 = 23,
AdpcmG722 = 24,
AdpcmG7233 = 25,
AdpcmG7235 = 26,
Alaw8 = 27,
Aes = 28,
DeltaMulaw8 = 29,
}
public Au(KaitaiStream p__io, KaitaiStruct p__parent = null, Au p__root = null) : base(p__io)
{
m_parent = p__parent;
m_root = p__root ?? this;
f_lenData = false;
_read();
}
private void _read()
{
_magic = m_io.ReadBytes(4);
if (!((KaitaiStream.ByteArrayCompare(Magic, new byte[] { 46, 115, 110, 100 }) == 0)))
{
throw new ValidationNotEqualError(new byte[] { 46, 115, 110, 100 }, Magic, M_Io, "/seq/0");
}
_ofsData = m_io.ReadU4be();
__raw_header = m_io.ReadBytes(((OfsData - 4) - 4));
var io___raw_header = new KaitaiStream(__raw_header);
_header = new Header(io___raw_header, this, m_root);
}
public partial class Header : KaitaiStruct
{
public static Header FromFile(string fileName)
{
return new Header(new KaitaiStream(fileName));
}
public Header(KaitaiStream p__io, Au p__parent = null, Au p__root = null) : base(p__io)
{
m_parent = p__parent;
m_root = p__root;
_read();
}
private void _read()
{
_dataSize = m_io.ReadU4be();
_encoding = ((Au.Encodings) m_io.ReadU4be());
_sampleRate = m_io.ReadU4be();
_numChannels = m_io.ReadU4be();
if (!(NumChannels >= 1))
{
throw new ValidationLessThanError(1, NumChannels, M_Io, "/types/header/seq/3");
}
_comment = System.Text.Encoding.GetEncoding("ASCII").GetString(KaitaiStream.BytesTerminate(m_io.ReadBytesFull(), 0, false));
}
private uint _dataSize;
private Encodings _encoding;
private uint _sampleRate;
private uint _numChannels;
private string _comment;
private Au m_root;
private Au m_parent;
/// <summary>
/// don't read this field, access `_root.len_data` instead
///
/// value `0xffff_ffff` means unspecified size
/// </summary>
public uint DataSize { get { return _dataSize; } }
public Encodings Encoding { get { return _encoding; } }
public uint SampleRate { get { return _sampleRate; } }
/// <summary>
/// number of interleaved channels
/// </summary>
public uint NumChannels { get { return _numChannels; } }
/// <summary>
/// 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.
/// </summary>
public string Comment { get { return _comment; } }
public Au M_Root { get { return m_root; } }
public Au M_Parent { get { return m_parent; } }
}
private bool f_lenData;
private int _lenData;
public int LenData
{
get
{
if (f_lenData)
return _lenData;
_lenData = (int) ((Header.DataSize == 4294967295 ? (M_Io.Size - OfsData) : Header.DataSize));
f_lenData = true;
return _lenData;
}
}
private byte[] _magic;
private uint _ofsData;
private Header _header;
private Au m_root;
private KaitaiStruct m_parent;
private byte[] __raw_header;
public byte[] Magic { get { return _magic; } }
public uint OfsData { get { return _ofsData; } }
public Header Header { get { return _header; } }
public Au M_Root { get { return m_root; } }
public KaitaiStruct M_Parent { get { return m_parent; } }
public byte[] M_RawHeader { get { return __raw_header; } }
}
}