Mathematica Import/Export Format

SND (.snd)

Registered MIME type: audio/basic
SND audio format.
Used for digital audio in computer and telecommunication systems and on the web.
Supports a variety of audio codecs, including lossless uncompressed PCM,

-law, a-law, and ADPCM voice compression.
Sometimes referred to as

-law format or Unix Audio Format.
The

-law algorithm is a standard method for compressing the dynamic range of a signal.
SND is an acronym derived from Sound.
Binary file format.
Supports various sampling frequencies and an arbitrary number of channels.
Identical to the AU format.
Developed by Sun Microsystems in 1992.

Import and Export support all audio codecs commonly used in the SND format.

IMPORT AND EXPORT

Import["file.snd"] imports an SND file, returning a sound object.

Export["file.snd", expr] exports a sound object to an SND file encoded using 8-bit pulse code modulation.

Import["file.snd"] gives an expression of the form Sound[SampledSoundList[data, r]].

Export["file.snd", expr] creates an SND file from the sound object expr.

Import["file.snd", elem] imports the specified element from an SND file.

Import["file.snd", {elem, sub_a, sub_b, ...}] imports a subelement.

Import["file.snd", {{elem₁, elem₂, ...}}] imports multiple elements.

The import format can be specified with Import["file", "SND"] or Import["file", {"SND", elem, ...}].

Export["file.snd", expr, elem] creates an SND file by treating expr as specifying element elem.

Export["file.snd", {expr₁, expr₂, ...}, {{elem₁, elem₂, ...}}] treats each expr_i as specifying the corresponding elem_i.

Export["file.snd", expr, opt₁->val₁, ...] exports expr with the specified option elements taken to have the specified values.

Export["file.snd", {elem₁->expr₁, elem₂->expr₂, ...}, "Rules"] uses rules to specify the elements to be exported.

See the reference pages for full general information on Import and Export.

ImportString and ExportString support the SND audio format.

ELEMENTS

General Import elements:

	"Elements"	list of elements and options available in this file
	"Rules"	full list of rules for each element and option
	"Options"	list of rules for options, properties and settings

Data representation elements:

	"Data"	raw audio samples, given as a list of lists of real numbers, each sublist representing an individual audio channel
	"SampledSoundList"	SND file given as SampledSoundList
	"Sound"	Sound object that plays as the sound

The "Data" element corresponds to the first argument of SampledSoundList.

Multiple channels are represented as an array of audio samples.

Import and Export use the "Sound" element by default for SND files.

Advanced Import element:

"SampleRate"

number of amplitude samples per second and channel

OPTIONS

General option:

SampleRate

Automatic

number of audio samples per second for each channel

Detailed properties and settings:

	"AudioChannels"	Automatic	the number of audio channels in the file
	"AudioEncoding"	"Integer8"	how samples are encoded

If the sample rate is not specified when exporting to SND, the highest sample rate occurring in the exported sound is used, and all sounds are resampled as necessary.

If the number of channels is unspecified, the highest number of simultaneous channels is taken, and silence is inserted if necessary.

If "AudioChannels" is set to a value n which is less than the number of channels to be exported, only the first n channels are exported.

The SND format supports PCM (pulse code modulation) and ADPCM (adaptive differential pulse code modulation) codecs, and various other audio encoding algorithms.

"AudioEncoding" can be set to any of the following codecs:

	"Integer8"	8-bit PCM
	"Integer16"	16-bit PCM
	"Integer24"	24-bit PCM
	"Integer32"	32-bit PCM
	"Real32"	32-bit IEEE floating point
	"Real64"	64-bit IEEE floating point
	"aLaw"	a-Law 4-bit PCM (ITU-T G.711)
	"uLaw"	-Law 4-bit PCM (ITU-T G.711)
	"G721-32"	32 kbps ADPCM (ITU G.721)
	"G723-24"	G.723 encoding at 24 kbps
	"G723-40"	G.723 encoding at 40 kbps

Not all codecs support arbitrary sample rates and channel specifications.