Audio sampling rates and formats.



Ever wondered how many sampling rates, audio formats and compression methods there are in this world? Here's a list with a short explanation.

Sampling Rates
Audio Formats

The info is here and there enriched with data from the AudioFormats-files by Guido van Rossum, with his personal approval.
Thank you Guido.

Sampling Rates.

Samples/sec

Description

5500

One fourth of the Mac sampling rate (rarely seen).

7333

One third of the Mac sampling rate (rarely seen).

8000

Exactly 8000 samples/sec is a telephony standard that goes together with U-LAW (and also A-LAW) encoding. Some systems use an slightly different rate; in particular, the NeXT workstation uses 8012.8210513, apparently the rate used by Telco CODECs.

11 k

Either 11025, a quarter of the CD sampling rate, or half the oldfers Macs sampling rate (used to be perhaps the most popular rate on the Mac until 44 Khz sampling became available with 640AV and 840AV Quadra's and later the PowerPC Macintoshes).

16000

Used by, e.g. the G.722 compression standard.

18.9 k

CD-ROM/XA standard.

22 k

Either 22050, half the CD sampling rate, or the Mac rate; the latter is precisely 22254.545454545454 but usually misquoted as 22000. (Historical note: 22254.5454... was the horizontal scan rate of the original 128k Mac).

32000

Used in digital radio, NICAM (Nearly Instantaneous Compandable Audio Matrix [IBA/BREMA/BBC]) and other TV work, at least in the UK; also long play DAT and Japanese HDTV.

37.8 k

CD-ROM/XA standard for higher quality.

44056

This weird rate is used by professional audio equipment to fit an integral number of samples in a video frame.

44100

The CD sampling rate. (DAT players recording digitally from CD also use this rate.). Unlike the older Macs of a few years ago, allmost all PowerPC Macs (including the new G3's) support audio sampling at 44.1 Khz.

48000

The DAT (Digital Audio Tape) sampling rate for domestic use.

Note:

When producing digital audio on your Mac, only use the following sample rates. They are widly supported and accepted:

  • 8000 8-bit U-LAW mono,
  • 22050 8-bit linear unsigned mono and stereo,
  • 44100 16-bit linear signed mono and stereo.

Audio Formats.

669

669 tracker module

AIF/AIFF/AIFF-C

Audio Interchange File Format Developed by Apple (who else...;-) for storing high-quality sampled sound and musical instrument data.
AIFF and AIFF-C: (.aif, .aiff, .aifc) AIFF stands for Audio Interchange File Format and was developed by Apple for storage of sounds in the data fork. It has been adopted by SGI and some other specialized applications. The Macintosh OS includes support for playing and creating AIFF files. More information about the format can be found in Inside Macintosh VI or Inside Macintosh: Sound. In addition, the format specification can be found at various places on the Internet. AIFF is a very flexible file format, allowing the specification of arbitrary sampling rates, sample size, number of channels, and application-specific format chunks which can be ignored by other applications. AIFF-C is basically AIFF with compressed samples. Apple supports two proprietary types of compression on the Macintosh, MACE 3-to-1 and MACE 6-to-1. Both are lossy compression algorithms, but provide reasonable quality with a great space savings. Recently, Apple has added support for µ-law and IMA 4:1 sub-formats, which are described below. In addition, the Apple II GS uses ACE 2-to-1 and ACE 8-to-3 compression. The very wellknown audioplayer SoundApp does not supports ACE files. Unlike SoundCap/Edit, 8-bit samples are stored as two's complement values. Lossy compression means the compressed sound will not sound exactly like the original sound, much like JPEGs do not look exactly like the original picture.

AIS

Velvet Studio Instruments

A-LAW

European telephony format audio. See also: AU

AMS

Extreme's Tracker module format

AMS

Velvet Studio Module

ASE

Velvet Studio Sample

AU

Sun/NeXT/DEC Audio file.
Sun Audio and NeXT: (.au, .snd) Internally, these are the same formats. SoundApp differentiates between them by file type or suffix merely for the user's benefit. The format specifies arbitrary sampling rates and multi-channel sounds. It supports a number of sound encodings, including µ-law, a-law, various linear formats of varying sample sizes, floating point samples, native DSP samples and G.72x ADPCM compression. SoundApp supports µ-law, a-law, 8-bit signed, 16-bit signed, G.721 ADPCM and both versions of G.723 ADPCM. Each µ-law sample is stored in 8 bits, but the meaning of the sample is different. Normal sound formats use linear encoding, whereas µ-law and a-law are logarithmic. This means that the spacing between the different sound levels grows progressively larger as the values increase. This format provides a larger dynamic range than normal 8-bit samples, approximately equivalent to 12-bit samples. However, it suffers from more noise than linear encodings. The G.721, G.723-24 and G.723-40 ADPCM formats are CCITT standards for compression of 8000-Hz 14-bit samples into a 32-, 24- or 40-kbps data stream. These compressed formats are not very popular due to the extremely slow decompression rates. Most files start with the four-character signature, '.snd', but there are some older, headerless .au files. These are assumed to be µ-law encoded, mono at 8000 Hz. A ".al" suffix will force the sound to be a-law, if it does not have a header. The U.S. telephone system uses µ-law encoding for digitization, whereas the European telephone systems use a-law encoding.

AVI

MS Audio Video Interleave file

AVR

Audio Visual Research sound file, used by some high-end commercial audio software. It can include some midi information.

C01

Typhoon wave files

CDR

Raw Audio-CD data.
Raw Audio CD Data: Raw 44.1-kHz, stereo, 16-bit samples in little endian format used by some CD-ROM authoring programs. SoundApp can play this format.

CD Audio

Audio CD Tracks: Using QuickTime SoundApp can extract the digitial data from audio CDs via the Import To QuickTime option. It will bring up a dialog box which allows various parameters to be set for the conversion. Be aware that audio tracks take up a huge amount of disk space.

DCM

DCM module format

DEWF

Macintosh SoundCap/SoundEdit recorded instrument format.
SoundCap: This is a Macintosh sound format created for use with an early audio digitizer. Version 4.3 of the application circa 1986 is the latest. It was written by Mark Zimmer and Tom Hedges from Fractal Software. It supported two basic flavors of sounds, compressed and uncompressed. Both types had 'FSSD' as the file type and 'FSSC' as the creator. Uncompressed files are just a series of 8-bit unsigned bytes in the data fork. Compressed files store information pertaining to sampling rate and a checksum. Sampling rates are limited to 5.6, 7.4, 11.1 and 22.2 kHz, and compression is done with a Huffman algorithm. Compressed SoundCaps are sometimes referred to as HCOM files because that is the first four characters of the file. SoundCap files can be played with SoundApp.

DIG

Digilink format

DIG

Sound Designer I audio file

DLS

DownLoadable Sounds

DMF

Delusion/XTracker Digital Music Fileformat

DSF

Delusion/XTracker Digital Sample Fileformat

DSM

Digital Sound Module tracker format

DTM

DigiTrekker module

DVI ADPCM

DVI ADPCM: (.adpcm) This is the Intel/DVI ADPCM (Adaptive Differential Pulse Code Modulation) format. It is a 4-to-1 compressed 16-bit file format. It is unique among the various ADPCM formats in that it's very fast, and like all ADPCM formats it is lossy. SoundApp supports the version of the format that plays mono at a 8000-Hz sampling rate.

DWD

DiamondWare Digitized file

EDA

Ensoniq ASR disk image

EDE

Ensoniq EPS disk image

EDK

Ensoniq KT disk image

EDQ

Ensoniq SQ1/SQ2/KS32 disk image

EDS

Ensoniq SQ80 disk image

EDV

Ensoniq VFX-SD disk image

EFA

Ensoniq ASR file

EFE

Ensoniq EPS file

EFK

Ensoniq KT file

EFQ

Ensoniq SQ1/SQ2/KS32 file

EFS

Ensoniq SQ80 file

EFV

Ensoniq VFX-SD file

EMD

ABT Extended MoDule

ESPS

ESPS audio files

EUI

Ensoniq EPS family compacted disk image

F2R

Farandoyle linear module format

F3R

Farandoyle blocked linear module format

FAR

Farandoyle tracker module

FFF

GUS PnP bank file format

FNK

FunkTracker module format

FSM

Farandoyle Sample format

G721

Raw CCITT G721 4bit ADPCM format data

G723

Raw CCITT G723 3 or 5bit ADPCM format data

GKH

Ensoniq EPS family disk image file

GSM

Raw GSM 6.10 audio stream.
GSM: (.gsm, .au.gsm) This compression algorithm is the European GSM 06.10 standard for full-rate speech transcoding, prI-ETS 300 036, which uses RPE/LTP (residual pulse excitation/long term prediction) coding at 13 kbit/s. It was developed for the European digital cellular phone system to make the most of tight bandwidth. Basically, what this means is that it analyzes and derives a mathematical formulation of small sections of speech using a model of the human vocal tract. Thus, it is optimized for speech reproduction and is in fact used in may Internet phone applications, although it seems to compress arbitrary sounds relatively well. The ".au.gsm" format consists of a series of 33-byte frames at sampled at a mono 8000 Hz. In spite of the fact that the suffix contains ".au" the files are not related to the Sun Audio (AU) files. The WAVE implementation uses a slight variation on the algorithm (they're good with these standards!) and can support mono files at an arbitrary sampling rate. SoundApp supports this file format.

GSM

US Robotics voice modems / QuickLink GSM format

HCOM

Sound Tools HCOM format

IFF

Interchange file format
Amiga IFF (8SVX): (.iff) This is the dominant format on the Commodore Amiga platform. It can specify an arbitrary sampling rate but only supports 8-bit sounds in stereo or mono. It also supports a 2-to-1 lossy compression format which uses a unique Fibonacci-delta compression algorithm. This format is supported by SoundApp.

IMA ADPCM

IMA ADPCM: This is a cross-platform standard from the Interactive Multimedia Association for sound playback. The basic algorithm is the same as in DVI ADPCM. SoundApp currently supports IMA data in WAVE, AIFF-C and 'snd ' resources. Unfortunately, Apple and Microsoft store their data in different ways. (So much for standards!) Both mono and stereo sounds are supported at an arbitrary sampling rate; however, the compression algorithm only accepts 16-bit samples.

INI

MWave DSP synthís mwsynthini GM-setup

INI

Gravis UltraSound bank setup

INRS

INRS-Telecommunications audio

INS

Ensoniq EPS family instrument

INS

Sample Cell / II Mac instrument

INS

Sample Cell / II PC instrument

IRCAM

IRCAM: (.sf) These files are used by academic music software such as the CSound package and the MixView sound sample editor. These files also specify an arbitrary sampling rate and can contain mono or stereo files. SoundApp only supports 8- and 16-bit samples, although the format can contain other encodings, e.g. floating point. The IRCAM format is supported by SoundApp.

IST

Digitrakker Instrument File

IT

Impulse Tracker module/instrument/sample

K25

Kurzweil 2500 sample

KR1

Kurzweil 2000 sample (multi-floppy)

KRZ

Kurzweil 2000 sample

MAT

Matlab variables binary file

MAUD

MAUD sample format

MDL

Digitrakker Module

MED

OctaMED tracker module

MIDI

MIDI: (.mid, .midi, .kar) Musical Instrument Digitial Interface is primarily a standard for communication between musical instruments. General MIDI (GM) is a standard for storing compositions based on what events happened during the performance. It does not contain digitized audio data; instead, it stores only the information about which notes were played in a time-line format. This is similar to the MOD format but without the digitized instrument samples. QuickTime 2.0 and later supports General MIDI data in QuickTime movies. SoundApp can directly play type 0, 1 and 2 MIDI files using QuickTime or OMS 2.1 or later and can also play MIDI data embedded in QuickTime movies. Note that lyric information from karaoke files is not displayed. There are several extensions to the GM standard, including GS (Roland) and XG (Yahama). SoundApp supports both of these extensions. It will also send all System Exclusive data to the selected MIDI output device if you are using the OMS MDI driver.

MOD

MOD: (.mod, .s3m, .mtm) This is not really a sound format but a music format. The format was "born" on the Amiga platform. It stores (1) digitized instruments and contains (2) a musical score (sequencing information that determines how and when to play which samples) which produces a lengthy composition with a very small amount of data.
The sequencing information in a MOD file contains 4 tracks of information describing which, when, for how long, and at what frequency samples should be played. This means that a MOD file can have up to 31 distinct (digitized) instrument sounds, with up to 4 playing simultaneously at any given point. This allows a wide variety of orchestrational possibilities, including use of voice samples or creation of one's own instruments (with appropriate sampling hardware/software). The ability to use one's own samples as instruments is a flexibility that other music files/formats do not share, and is one of the reasons MOD files are so popular, numerous, and diverse.
There have been various extensions to this format, but SoundApp only supports a subset using two different drivers. These include Amiga SoundTracker, NoiseTracker, Protracker, Amiga StarTracker (4- and 8-track), Oktalyzer (4-8 tracks), Amiga MED/OctaMED (4-16 tracks, MMD0/1/2 formats), IBM FastTracker (4-, 6- and 8-track), IBM TakeTracker (1-32 tracks). Using the ZSS driver, SoundApp also supports S3M (ScreamTracker 3), MTM (Multitracker) and the 'MADF' and 'MADG' formats used by Player Pro for the Macintosh. Playback of XM or 669 files is not currently supported by either driver.

MOV

QuickTime Movies: (.mov) This is the Apple standard for time-based multimedia files. Versions 1.x support moving pictures, sound and later versions support text. QuickTime 2.0 added MIDI tracks via a software synthesizer or external synthesizer in 2.5 and later. QuickTime 2.0 or later and the QuickTime Musical Instruments extension must be installed in order to play QuickTime MIDI files with SoundApp. SoundApp can deal with MACE, IMA and µ-law compressed QuickTime sound tracks.

MPA/MPEG

MPEG Audio: (.mp, .mp2, .mp3, .m1a, .m2a, .mpg, .mpeg, .swa) MPEG stands for the "Moving Picture Experts Group," working under the joint direction of the International Organization for Standardization (ISO) and the International Electro-Technical Commission (IEC). This group works on standards for the coding of moving pictures and associated audio. MPEG audio files can be either layer I, II or III. Increasing layer numbers add complexity to the format and require more effort to encode and decode. However, they also provide higher playback quality for the sample bit rate. SoundApp supports layers I, II and III. To further complicate matters, MPEG files come in two flavors, MPEG-1 and MPEG-2. The encodings for the three layers are mostly the same; however, MPEG-2 streams have more compact header information. Files can have sampling rates of 32000, 44100 and 48000 Hz for MPEG-1 and 16000, 22050 and 24000 Hz for MPEG-2. Data can be in stereo or mono and decompresses to 16-bit resolution. MPEG compression is a lossy algorithm based on perceptual encodings, which can achieve high rates of compression without noticable decreases in quality. Typical compression rates are around 10-to-1. SoundApp supports MPEG audio only on Macs with a PowerPC processor. Finally, Macromedia's Shockwave streaming audio system uses a MPEG-1 Layer III encoding with a non-standard header, which SoundApp will ignore. They frequently have a ".swa" suffix.
More info on MPEG Audio can be found at http://www.mpeg.org/.

MTM

MultiTracker Module

MUS10

Mus10 audio

MWS

MWave DSP synthís instrument extract

NIST

NIST Sphere audio

O01

Typhoon vOice file

OKT

Oktalyzer tracker module

PAC

SB Studio II package

PAT

Advanced Gravis Ultrasound / Forte tech Patch

PCM

OKI MSM6376 synth chip PCM format

PLM

DisorderTracker2 module

PLS

DisorderTracker2 sample

PRG

WAVmaker program

PSB

Pinnacle Sound Bank

PSION

PSION a-law audio.
PSION sound: (.wve) This format consists of a short header followed by a-law encoded samples at 8000 Hz. It is used by the PSION Series 3 palmtop personal information manager and uses a ".WVE" suffix.

PSM

Protracker Studio Module Format

PTM

Poly Tracker module

RA

RealAudio, streaming audio on Internet: http://www.real.com/

RAW

Raw signed PCM data

RIFF WAVE

A format by Microsoft and IBM, first included within Windows 3.1. Better known as .WAV (see below).

RM

RealMedia, streaming audio and video on Internet: http://www.real.com/

SAM

Signed 8bit Sample data

SB

Raw Signed Byte (8bit) data

SBK

Emu SoundFont v1x Bank files / Creative Labs SB AWE 32

SD1

Sound Designer audio.
Sound Designer: Digidesign's predecessor to the Sound Designer II format. Unlike the second generation format, it does not use resources to store header information. It has a large header, although most of it is used internally by their software. It can only contain mono data. Most files are usually 16-bit, 44.1 kHz. SoundApp plays this fileformat. SD is also the standard working format for most professional harddisk recording software, such as Deck II.

SDII

Sound Designer II: This is a popular format for professional sound editing on the Macintosh. Deck II is a good example. It can specify arbitrary sampling rates and supports multiple channels and data sizes. Information regarding the specifics of the sound are stored in three 'STR ' resources. Like VOC, 8SVX and WAVE, samples are encoded as signed values. SoundApp plays this format.

SDK

Roland S-series floppy disk image

SDS

Raw Midi Sample Dump Standard file

SDW

Raw Signed DWord (32bit) data

SDX

Midi Sample Dump Standard files as compacted by SDX

SF

IRCAM SoundFile format

SF2

Emu SoundFont v20 file

SFD

SoundStage Sound File Data

SFI

SoundStage Sound File Info

SFR

Sonic Foundry Sample Resource

SMP

Samplevision format

SMP

Ad Lib Gold Sample

.snd

See: AU

SND

AKAI MPC3000 sample

SND

Apple SND systemsound format
System 7 and 'snd ': System 7 sound files are simply type 1 'snd ' resources stored with a type of 'sfil' and a creator of 'movr'. System 7 provides the familiar icon for them and permits playback in the Finder by double-clicking on them. An 'snd ' is a type of resource which consists of a series of commands for use by the Sound Manager. In addition to digitized sound samples, 'snd ' resources can contain direct frequency-modulated and wave table-based sounds. Any number of the three types can be combined with various effects to produce complex sound files. Simple Beep is an example of a non-digitized 'snd '. There are two types of 'snd ' resources, amazingly called type 1 and type 2. Type 1 is the format described above and is referred to as the System sound format. Type 2 is for use with HyperCard and can contain only a sampled (digitized) sound. SoundApp can play both types but will only convert sampled sounds. For more information on 'snd ' files consult Inside Macintosh VI or Inside Macintosh: Sound. A familiarity with the Resource Manager would also be helpful. 8-bit samples are stored as unsigned bytes, like SoundCap/Edit, but 16-bit samples are signed, like AIFF. Stereo 'snd ' resources are also possible, but Sound Manager 3.0 or later is required to play 16-bit samples directly. The possible types of compression for 'snd ' resources are the same MACE, IMA and µ-law types used in AIFF-C files. SoundApp plays these files.

SNDR

Sounder sound file

SNDT

Sndtool sound file

SOU

SB Studio II sound

SoundCap

See: DWEF

SoundEdit

SoundEdit: This is the same file type as uncompressed SoundCap (DWEF) for mono sounds. In addition, it adds to the resource fork some information about colors, labels, looping segments and the format. The most useful for playback is the 'INFO' resource, which stores the sampling rate, limited to the same four as SoundCap. Stereo files consist of the left and right channels stored back-to-back in the data fork. MACE-3 and MACE-6 compression is supported for mono 22 kHz files only, which is a limitation of the SoundEdit. SoundEdit also supports 4:1 and 8:1 compression, but SoundApp does not support these proprietary compression algorithms. The 'INFO' resource specifies the lengths of each channel, which can be different. SoundEdit came with the MacRecorder sound digitizer from Farallon and later by Macromedia. SoundEdit Pro and SoundEdit 16 are more recent incarnations, and they support a much larger format suite, including up to 48-kHz samples and 16-bit resolution. They shed the limitations inherent in the original format. SoundApp does not currently support SoundEdit Pro or SoundEdit 16 files.

SPD

Speach Data file

SPL

Digitrakker Sample

SPPACK

SPPack sound sample

SSI

Studio Session Instrument: This format is primarily used with Super Studio Session and stores digitally sampled instruments. There are two types: compressed and uncompressed. Compressed instruments have the same format as compressed SoundCap files, and uncompressed instruments are likewise similar to uncompressed SoundCap files, with the addition of an eight-byte header.

STM

Scream tracker v2 module

S3I

Scream tracker v3 instrument

S3M

Scream tracker v3 module

SVX

Interchange file format, 8SVX/16SV

SW

Raw Signed Word (16bit) data

SWA

Shockwave audio: streaming audio on Internet: http://www.macromedia.com/

SYW

Yamaha SY-series wave files (really named W??)

TXT

Ascii Text formatted audio data

TXT

Ascii Text parameter description

TXW

Yamaha TX16W wave files (really named W??)

UB

Raw Unsigned Byte (8bit) data

UDW

Raw Unsigned DWord (32bit) data

U-LAW

US telephony format (CCITT G711) audio. See also: AU.

ULT

UltraTracker modules

UNI

MikMod 'UniMod' format

UW

Raw Unsigned Word (16bit) data

UWF

UltraTracker Wave File

V8

Covox 8bit audio

VAP

Annotated speech

VOC

Sound Blaster VOC: (.voc) This is the format used by the Creative Voice SoundBlaster hardware used in IBM-compatible computers and is optimized for that hardware. It specifies the sampling rate as a multiple of an internal clock and is not as flexible as the other general formats. Data can be segmented and portions of silence can be added. SoundApp supports both of these features, but not the looping feature.

VOX

Dialogic adpcm

VOX

Talking Technology Incorporated file

W??

Yamaha waveforms (see TXW, SYW)

W01

Yamaha TX16W wave

W01

Yamaha SY-series wave

WAV

Windows WAVE: (.wav) This format was created by Microsoft and IBM, and it has unfortunately become a popular standard. Like AU, it specifies an arbitrary sampling rate, number of channels and sample size. It also specifies a number of application-specific blocks within the file. It has a plethora of different compression formats, although the Microsoft ADPCM is the most popular. SoundApp only supports 8-bit, 16-bit, 32-bit, µ-law, a-law, GSM-, IMA ADPCM- and MS ADPCM-compressed sounds. IMA and MS ADPCM provide a 4-to-1 compression ratio and GSM provides an approximately 9.7-to-1 compression ratio. All data fields and 16-bit samples are stored in little-endian notation, as Intel processors require. All other formats supported by SoundApp use big-endian notation which means the high-bytes come first in the data stream.

WFB

Turtle Beach WaveFront Bank (Maui/Rio/Monterey)

WFD

Turtle Beach WaveFront Drum set (Maui/Rio/Monterey)

WFP

Turtle Beach WaveFront Program (Maui/Rio/Monterey)

WVE

Psion sound

XM

Fast Tracker 2 extended module

XI

Fast Tracker 2 instrument




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