A Short Guide To

Audio Mastering & CD Manufacture

Home Email: info@the-digital-audio.co.uk

Introduction

CD Mastering room SkiptonThis page is designed as a brief guide to the processes involved in turning your studio master into Mp3s for download or saleable audio CDs. It is impossible to cover every aspect in depth, but we hope that this information will help you make informed, sound decisions and to avoid costly mistakes. We have made every effort to ensure that the information is accurate, but technology and processes are changing rapidly. If you are unclear about anything please do ask.

After the recording studio

Once you have been in the sound studio and spent time, energy, effort, and possibly a considerable amount of money committing your project to disc (or tape), you probably want to have it duplicated either for sale to the public or for distribution to record companies, etc. in order to secure a deal. Hopefully the sound studio will have done a good job for you, and you will be pleased with your  music master. There are now various process which your material will need to pass through in order to be manufactured or committed to a Download site.

Initially these are the same for Mp3 and audio CD but they then diverge and there is a separate section for each of these.

The diagram below should illustrate this (stages in blue are optional):

Original recording studio master

Audio Mastering process 

Sound Editing process

Pre-mastering

Mp3 production master

CD production master

Encoding as Mp3 master

Glass master

Loading to Download site

Individual audio CDs

Mastering & Pre-Mastering

The audio master which you have recorded and mixed at the studio is normally known as an ‘Original Master’. It will usually be on either a Digital Audio Tape (DAT), which should ideally be recorded with a sampling frequency of 44.1 kHz, with start identification marks (Start IDs) and absolute time (A Time) or Timecode, or as audio files (such as .wav, AIFF, etc). Many studios will get your material in the right sequence, but it is often then necessary to make adjustments in order to create a Production Master which can be sent to a factory for manufacture. This involves pre-mastering and may also include audio mastering:

Creative processing including equalisation, compression and multi-band dynamics can dramatically increase the impact of a piece of music by adding extra energy and allowing a higher average level. There is often an improved sense of space. Experience has shown that having a new and fresh pair of ears at the end of a project can yield an improvement of between 5 and 50%! It’s definitely worth considering. We have the ability to make your music LOUD, but consider the implications before asking. You might like to read this article from The Guardian.

Pre-Mastering - preparing and creating production audio masters.

Material is checked for technical faults in the sound (overloads, distortion, clicks, drop-outs, etc.) and then a Production Master is created which is suitable for the format required:

The Digital Audio Company uses either DDPi files on DVD-R or DDP Exabyte for CD production masters because it is very secure. We have run extensive listening and data tests, comparing original source material with production CDs to check that what the client supplies is what the final CDs sound like. We have never found any evidence of changes in sound when DDP is used.

Quality control is very important during audio CD pre-mastering. All CD masters are fully auditioned for audible problems either as they are loaded onto the edit system or played out. Our DAT machines have error indicators and the edit system analyses the digital audio for errors. As the master is being written it is automatically checked for data errors which are corrected. Once the master is written it is then verified (double checked) and for Exabytes and 1610 masters a report is printed to guarantee the quality. PQ coding is the process which adds extra information to the CD which tells the CD player where each song starts and stops, and its duration.

An audio CD can have up to 99 tracks and each track can contain up to 99 index points (although not all CD players can access indices).

It is also possible to embed a Bar Code number and International Standard Recording Codes (ISRC) into the table of contents on an audio CD to identify the owner of each track. ISRC's consist of a series of letters and numbers which are allocated by the PPL in the UK, and regulated worldwide by the IFPI. ISRCs can be used by radio stations, etc., to automatically log play out of your material for royalty payments. Visit their web site or for more contact information see our links page.

CD text is a relatively new addition to the CD specification and we can include information such as track title, composer, arranger and artiste when creating a DDPi master. Please ensure that you supply all CD text information with the correct spelling.

 

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Page last updated Thursday 25th February 2010 at 19:00.