NAME

Audio::Sndfile::Info - describe an opened audio file

SYNOPSIS

    my $info = Audio::Sndfile::Info.new(channels => 2, samplerate => 44100, format => 0x00010002);
    say $info.type;

DESCRIPTION

The objects of type undefined can be passed to the constructor of Audio::Sndfile when opening the file for writing and can be obtained from the info accessor of an Audio::Sndfile that was opened for reading. It is a representation of the SF_INFO struct used by libsndfile to pass this information around.

It is unlikely that changing the values of any of the attributes in the object will make sense after the object has been constructed.

METHODS

Where indicated some of these attributes can be passed as named arguments to Audio::Sndfile constructor when opening for writing.

frames

This returns an Int indicating the number of the frames in a file, this only makes sense when the file is opened for reading, it is ignored when the file is opened for writing and it is not updated while new data is written to the file. The number of frames is the number of sample items / channels.

channels

The number of channels in the data of this file. This is required when opening a file for writing.

format

An Int that describes the format of the file. This is the bitwise or of type, sub-type and endian. It is required when opening a file for writing and providing a value that is not legal will result in an exception.

samplerate

This is the sample rate of the frame data in frames / second. This is required when opening a file for writing. It is important to note though that if data is being read from one file and written to the other (i.e. copying or format converting) then setting this to any other value than that of the incoming file will not cause an automatic sample rate conversion and will simply have the effect of slowing down or speeding up the playback of the written data. If you want samplerate conversion you will either need to process the data yourself to add or remove the required frames (inferring the values in the up-sampling case,) or use some other library such as libsamplerate.

sections

An Int that indicates the number of (format dependent) sections in the file. This is not required for opening a file for writing.

seekable

This is a Boolean to indicate whether the input or output file is seekable, it will be true for most regular files and False for other special files, however as it is currently difficult to open other than regular files this can be mostly ignored.

format-check

method format-check() returns Bool

This returns a Bool to indicate whether the format in the current object makes sense. Attempting to use a setting of format where this is not true will cause an exception to be thrown.

type

method type() returns Format

This is a value of the enum undefined that indicates the major format of the file (e.g. WAV, FLAC ..). It is bitwise or-ed with sub-type and endian to provide format.

sub-type

method sub-type() returns Subformat

This is a value of the enum undefined that indicate the minor format or sample encoding of the data (e.g. PCM_16, FLOAT ... ). It is bitwise or-ed with type and endian to provide format.

endian

method endian() returns End

This is a value of the enum undefined which indicates the endian-ness of the samples in the data. It is bitwise or-ed with type and sub-type to make format.

duration

method duration() returns Duration

enum Audio::Sndfile::Info::Format

This describes the major format of the file as described above in type. The possible values are described below, it should be borne in mind that only certain combinations of type and sub-type make sense, this is detailed in http://www.mega-nerd.com/libsndfile/#Features

• WAV

Microsoft WAV format (little endian default).

• AIFF

Apple/SGI AIFF format (big endian).

• AU

Sun/NeXT AU format (big endian).

• RAW

RAW PCM data.

• PAF

Ensoniq PARIS file format.

• SVX

Amiga IFF / SVX8 / SV16 format.

• NIST

Sphere NIST format.

• VOC

VOC files.

• IRCAM

Berkeley/IRCAM/CARL

• W64

Sonic Foundry's 64 bit RIFF/WAV

• MAT4

Matlab (tm) V4.2 / GNU Octave 2.0

• MAT5

Matlab (tm) V5.0 / GNU Octave 2.1

• PVF

Portable Voice Format

• XI

Fasttracker 2 Extended Instrument

• HTK

HMM Tool Kit format

• SDS

Midi Sample Dump Standard

• AVR

Audio Visual Research

• WAVEX

MS WAVE with WAVEFORMATEX

• SD2

Sound Designer 2

• FLAC

FLAC lossless file format

• CAF

Core Audio File format

• WVE

Psion WVE format

• OGG

Xiph OGG container

• MPC2K

Akai MPC 2000 sampler

• RF64

RF64 WAV file

enum Audio::Sndfile::Info::Subformat

These describe the minor format or sample encoding of the format. As suggested above only certain combnations of Format and Subformat actually make sense.

• PCM_S8

Signed 8 bit data

• PCM_16

Signed 16 bit data

• PCM_24

Signed 24 bit data

• PCM_32

Signed 32 bit data

• PCM_U8

Unsigned 8 bit data (WAV and RAW only)

• FLOAT

32 bit float data

• DOUBLE

64 bit float data

• ULAW

U-Law encoded.

• ALAW

A-Law encoded.

• IMA_ADPCM

IMA ADPCM.

• MS_ADPCM

Microsoft ADPCM.

• GSM610

GSM 6.10 encoding.

• VOX_ADPCM

OKI / Dialogix ADPCM

• G721_32

32kbs G721 ADPCM encoding.

• G723_24

24kbs G723 ADPCM encoding.

• G723_40

40kbs G723 ADPCM encoding.

• DWVW_12

12 bit Delta Width Variable Word encoding.

• DWVW_16

16 bit Delta Width Variable Word encoding.

• DWVW_24

24 bit Delta Width Variable Word encoding.

• DWVW_N

N bit Delta Width Variable Word encoding.

• DPCM_8

8 bit differential PCM (XI only)

• DPCM_16

16 bit differential PCM (XI only)

• VORBIS

Xiph Vorbis encoding.

Audio::Sndfile::Info::End

These describe the endian-ness of the file format. Typically a file opened for reading will use File if the format defines an endian-ness and this should also be used when opening a file for writing unless there is some particular reason not to.

• File

Default file endian-ness

• Little

Force little endian-ness

• Big

Force big endian-ness.

• Cpu

Force CPU endian-ness.