16bit - see Bit Depth

24bit - see Bit Depth

44.1kHz - see Sampling Frequency

48kHz - see Sampling Frequency

96kHz - see Sampling Frequency

A to D Converter or Analogue to Digital Converter is a stand alone piece of hardware or a computer interface that will digitize an analogue audio signal. The quality of the A to D converter will affect how accurately the digital audio compares to the original analogue signal.

AAC - see Compressed files

Abbey Road Online Mastering is an online extension of Abbey Road's Mastering facilities. For over 50 years artists and producers have come to the studios in North West London to have their recordings and mixes optimised [tr. verb ~ to make something function at its best or most effective.] at the Mastering stage i.e. the final creative stage of the audio recording process. With more people than ever making music we have tried to make our expertise and equipment available to anyone with music to master and an internet connection.

Abbey Road Studios has been at the forefront of music recording and production since 1931. For more information on what we've done and what we do please visit our website at www.abbeyroad.com.

Ableton Live is a popular music production software application. If you use Ableton and would like to use Abbey Road Online Mastering for your mixed tracks then export them and/or record them as stereo WAV's or AIFF's and try us out.

AIFF - AIFF (Audio Interchange File Format) is Apple Inc.'s uncompressed digital audio file format, and along with WAV's are currently the most commonly used uncompressed digital audio file formats.

Audio Codecs can be either hardware or, more commonly, software tools that can compress and decompress digital audio data to a given audio file format such as MP3, WMA, AAC, Ogg Vorbis, and FLAC. See Compressed files.

Bit Depth is the number of bits contained in each sample of digital audio. Standard audio CD's are 16 bit (with a Sampling Frequency of 44.1kHz) while other formats such as DVD-A can contain 24 bit samples (at 96kHz sampling rates). As a general rule the lower the bit depth (and sampling frequency) the lower the quality of (PCM) digital audio.

A binary number containing 16 0's or 1's is equivalent to 2¹⁶ or a range of 65536 decimal states per sample while a binary number containing 24 0's or 1's is equivalent to 2²⁴ or a range of 16777216 decimal states per sample. Therefore files with higher bit depths have higher file sizes and require greater storage capacity.

Bit Rate is the rate at which the bits of a digital audio file are transferred or processed per unit of time. The bit rate is measured in bits per second (bps) and generally prefixed with the SI standard kilo (kbps) or Mega (Mbps). Files with higher bit rates are of a greater quality, have higher file sizes and therefore require greater storage capacity.

BLUE Book is the technical term for an Enhanced CD (ECD) a 'multi-session' CD containing audio data which plays in a CD player and video/data content which is accessible via one's computer.

Blu-Ray is a relatively new optical disc storage media. It has the same physical size as a standard CD or DVD though a single layer Blu-Ray disc can store up to 25GB of data.

Brick Wall Limiting - see Peak limiting

Checksum is a way to determine the integrity of data sent across a network or via media. A checksum is generated at source and transferred with the subject data while another check is carried out upon delivery and any discrepancies with the source checksum indicates the data has become corrupted. If the sums are the same the data has been transferred successfully. We are currently developing the use of checksums for use within Abbey Road Online Mastering.

Compressed files are files that have been reduced in size to make them easier to store, copy, email, etc. There are generally two types of file compression; 'lossless' and 'lossy'.

FLAC and MLP are examples of lossless data compression where the uncompressed WAV or AIFF can be reduced in file size by 50% with no degradation in audio fidelity. Similarly Zip/Unzip is a form of lossless data compression which we use at Abbey Road Online Mastering to facilitate the upload of multiple titles in one hit.

MP3 and AAC are examples of lossy compressed files where "unwanted" data from the uncompressed WAV or AIFF is discarded sometimes reducing file sizes to 10% of the original (subject to the encoded file's Bit Rate) resulting in significant degradation of audio fidelity. They may be quicker to upload however due to this compromise in audio fidelity we don't accept lossy compressed files at Abbey Road Online Mastering.

Another common file compression type, developed by Microsoft, is WMA, (Windows Media Audio) which can be both lossless and lossy subject to which Windows Audio Codec is used. Either way Compressed files should not be confused with . . .

Compression (Audio) is the reduction of an audio signal's Dynamic Range by altering the ratio of input level to output level starting at a defined threshold.

Copper - see DMM.

Cubase is a widely used music production software program developed by Steinberg. If you use Cubase and would like to use Abbey Road Online Mastering for your mixed tracks then export them and/or record them as stereo WAV's or AIFF's and try us out.

D to A Converter or Digital to Analogue Converter is a stand alone piece of hardware or a computer interface that converts a digital audio signal for use in the analogue world i.e. our ears. The quality of the D to A converter will affect how accurately the analogue signal compares to its digital counterpart.

DAW or a Digital Audio Workstation is a computer based system used, in conjunction with proprietary hardware, to record and manipulate audio and MIDI data. DAW's popular at Abbey Road are Pro Tools, SADiE, Pyramix and Sonic SoundBlade.

DDP - Disc Description Protocol is a type of image file used in the production of audio CD's. It includes files such as the audio content of the disc as well track timings and any other additional information. CD manufacturing houses accept DDP images and can be stored on a CD/DVD ROM or easily transferred over a network.

Digital Performer is a commonly used DAW made by MOTU (Mark of the Unicorn). If you use Digital Performer and would like to use Abbey Road Online Mastering then export your mixed tracks as stereo WAV's or AIFF's and try us out.

DMM or Direct Metal Mastering pertains to a specific method of cutting to copper rather than Lacquer discs for the production of vinyl masters. Copper masters generally produce a clearer sound while lacquer masters are preferred for dance music due to their warmer bass response. Abbey Road Online Mastering has two DMM cutting lathes and one lacquer lathe.

Dolby Digital (DD or AC3) is a type of data rate reduction algorithm, not dissimilar to DTS, and is usually used for stereo or surround sound audio on standard DVD-V's.

DSD (Direct Stream Digital) is a type of digital audio stream developed by Sony and Philips and is used on SACD's (Super Audio Compact Discs). Where PCM audio on standard CD's have 16 bit samples at a Sampling Frequency of 44.1kHz, DSD audio uses 1 bit samples at a rate of 2.8224MHz i.e. 1 bit x 64 x 44.1kHz).

DTS is a type of data rate reduction algorithm, not dissimilar to Dolby Digital, and is usually used for surround sound audio on standard DVD-V's. DTS arguably sounds better than its Dolby Digital counterpart although both DTS and Dolby now provide a lossless encoder for use on the Blu-Ray.

DVD-A (Digital Versatile Disc Audio) is an audio only (albeit with some graphics but no video content) type of DVD allowing stereo and surround sound without the need for reduced quality caused by lossy Compressed file data rate reduction such as Dolby Digital or DTS. Moreover DVD-A's use a lossless type of data rate reduction known as MLP (Meridian Lossless Packing) to pack more information on the disc. It is also possible to have a DVD hybrid disc containing both DVD-V and DVD-A content.

DVD-V (Digital Versatile Disc Video) is the type of DVD usually used for movies with audio, and graphics. All the surround sound audio must be data rate reduced (see Dolby Digital or DTS) while stereo sound can be at the full data rate with no reduction.

Dynamic range of a piece of music is the difference between the loud parts and the quiet parts. Many modern recordings are, at the artist's or producer's request, mastered as loud as possible (so they stand out on your iPod) however this is at the expense of a track's dynamic range.

EQ or Equalisation is used throughout the recording process to enhance and reduce the requisite frequencies of a track's component instruments and parts. In the Mastering environment EQ is applied to increase or decrease certain frequencies over the whole track to make it more suitable for playback in a club or on the radio for example.

Free Lunch is an imaginary artifact often associated with Peak Limiting.

FTP or File Transfer Protocol is a method of transferring data from one computer to another across the internet or through a network. Abbey Road Online Mastering uses a secure form of FTP when receiving and returning tracks.

GarageBand is a software application developed by Apple for Mac OS X. If you use GarageBand and would like to use Abbey Road Online Mastering for your mixed tracks then record/export them as stereo WAV's or AIFF's and try us out.

ICPN (International Code Product Number) is a unique 13 digit number record companies use to identify a physical audio product. For example the ICPN for the CD version of an artist's album will differ from the ICPN for the vinyl version.

ISRC Code or the International Standard Recording Code is a 12 digit code that uniquely identifies a sound recording used anywhere in the world. They are used to facilitate the logging of radio plays and therefore royalty collections. In the UK in order to obtain ISRC's you need to become a member of the PPL (Phonographic Performance Limited) who can be found at www.ppluk.com.

Lacquer indicates the material used during the production of vinyl mastering when cutting to lacquer rather than copper (DMM) discs. Copper masters generally produce a clearer sound while lacquer masters are preferred for dance music due to their warmer bass response. Abbey Road Online Mastering has two DMM cutting lathes and one lacquer lathe.

Limiting is a type of compression, with a high, usually 10:1 or greater, compression ratio i.e. a 10dB change at the input will cause only a 1dB change at the output. Limiting with a compression ratio of infinity: 1 is known as Peak limiting (also called brick wall limiting).

LOGIC Pro, Logic Express and Logic Studio are popular DAW's currently owned by Apple Inc. If you use Logic and would like to use Abbey Road Online Mastering then export your mixed tracks as stereo WAV's or AIFF's and try us out.

Lossless Compression - see Compressed files

Lossy Compression - see Compressed files

Mastering or (Abbey Road Online Mastering) is the final creative stage of the audio recording process and generally includes EQ'ing, compressing, limiting, and assembling individual tracks to make a final product. When there is more than one track the final running order and the gaps between the tracks may need to be determined by the artist. Even in these days of shuffling iPods there are still some people who listen to an album from start to finish!

MD5 Checksum - see Checksum

MIDI (Musical Instrument Digital Interface) has since 1983 been an industry standard protocol that enables electronic musical instruments, computers, etc. to communicate, control and synchronise with each other. MIDI does not transmit an audio signal moreover it transmits time related event messages such as note value and velocity which can be recorded, manipulated if necessary then played back.

MLP (Meridian Lossless Packing) - see DVD-A

MP3 - see Compressed Files

ORANGE Book is the Philips/Sony set of specifications for CD-R's.

PCM (Pulse Code Modulation) is a digital representation of an analogue signal which has been sampled at regular intervals and is used for uncompressed digital audio in computers and on standard Red book CD's.

Peak Limiting or Brick Wall Limiting is used to make sound artificially loud. It can be likened to driving your VW beetle into the back wall of your garage where the rear end (quieter sounds) get closer to the front end (louder sounds), but the curve of the bonnet gets progressively squashed and arguably less attractive the more you crush it.

PMCD or Pre-master CD was originally used to describe a CDR which contained additional information designed to be used to speed up the manufacturing process. Now used to describe a CDR that has been checked and auditioned and has been passed as suitable to be used for manufacturing audio CDs

PMF or Pyramix Media Format is an audio file format exclusive to the Pyramix DAW. We use PMF's around the studios but not within Abbey Road Online Mastering yet.

Post Production in a professional audio facility is a catch all term for all the operations that can be carried out on audio once it has been mixed. At Abbey Road this includes Mastering (stereo and surround), Abbey Road Online Mastering, Re-Mastering (stereo and surround), Copying and bulk CD Duplication.

Pro Tools is a very common DAW used throughout professional recording studios and bedroom studios alike. If you use Pro Tools and would like to use Abbey Road Online Mastering then export your mixed tracks as stereo WAV's or AIFF's and try us out.

Reason is a very popular software music production application made by Propellerheads. If you use Reason and would like to use Abbey Road Online Mastering for your mixed tracks then record them as stereo WAV's or AIFF's and try us out.

RED Book is the Philips/Sony set of specifications for replicated (manufactured) audio CD's.

SACD (Super Audio Compact Disc) is an optical audio disc format developed by Sony/Philips aimed at providing higher fidelity digital audio than CD. SACD's use the DSD data stream for this high quality audio while Hybrid SACD's contain two layers, one being conventional 16 bit 44.1kHz audio, the other being SACD. When played in a suitable player, the laser can focus on the layer required.

SADiE 5 is the DAW (Digital Audio Workstation) most widely used in Abbey Road's Post Production department.

Sampling Frequency or Sample Rate is the number of times per second a continuous (analogue) audio signal is sampled to create a discrete (digital) signal. A sample of digital audio has a binary value with a predetermined Bit Depth. Standard audio CD's have sampling frequencies of 44.1kHz (i.e. 44,100 samples per channel per second with a bit depth of 16 bits) while other formats such as DVD-A can have 96kHz sampling frequencies (at a bit depth of 24 bits). As a general rule the lower the sampling frequency (and bit depth) the lower the quality of (PCM) digital audio.

A greater number of samples per second results in a wider frequency range. The highest frequency that can be recorded is approximately half the sampling frequency. Other sample rates used in professional recording environments are 48kHz (common when using video), 88.2kHz, 96kHZ, and 192khz. Therefore files with higher sampling frequencies have higher file sizes and require greater storage capacity.

Scarlet Book - the technical term for the SACD.

SDII or SD2 (Sound Designer 2) is, or was, DigiDesign's (Pro Tools) proprietary audio file format which has now been superceded by WAV's and AIFF's.

Sonic SoundBlade, formerly Sonic Solutions, is a widely used DAW one of which is at Abbey Road.

Stuffit is a family of software utilities for archiving and compressing files on Apple Mac computers. Abbey Road Online Mastering currently doesn't accept Stuffit files as the current OSX platform comes with the alternative Zip/Unzip utility.

WAV or WAVE (Waveform Audio File Format) is an uncompressed digital audio file format, developed by Microsoft and IBM, and along with AIFF's are currently the most commonly used uncompressed digital audio file formats. A BWF (Broadcast Wave Format) is a WAV file that also carries time position information commonly used in conjunction with video content.

WinZip - see Zip/Unzip

WMA (Windows Media Audio) - see Compressed files.

Zip/UnZip or WinZip, developed for Microsoft, is a software utility for archiving and compressing files. Zip is a form of lossless compression so the integrity of the audio files remains intact.