Concept and delimitation
The mastering meant here should not be confused with the last preparatory production step before the actual pressing process, which is also referred to as (technical) mastering and includes the creation of the master ( glass master for CDs and die for vinyl record pressing).
Audio mastering involves the preceding steps of post-production and editing of the sound or data material and the final creation of a "premaster CD" ( premastering ) or a DDP ( disc description protocol ) master, which is used as a positive template for the creation of the master in the press shop.
Since the short term mastering has generally prevailed for audio mastering , the demarcation should be clarified again using the steps of an exemplary CD production today:
- Music / sound recording ( tracking ) in multi-track mode
- Mixing ( mix , mixdown ) of the individual tracks on a stereo or surround sound track (the so-called sum )
- Post-processing of the stereo / surround sound sum through the actual audio mastering
- Creation of the premaster as a positive template for the glass master ( premastering )
- Creation of the glass master as a negative press template in the press shop for CD production (also known as mastering )
Steps 1 through 3 are music production steps. Step 4 is usually also carried out by a mastering engineer.
Goal and implementation steps
The goals of mastering are to give the audio material a better quality and to enable playback compatibility on as many technical devices and media as possible. A professional sound recording should sound just as good when played back on a small stereo system as, for example, when it is broadcast on the radio or played through headphones. A balanced stereo image, good mono compatibility and a balanced frequency response play a major role here. In the mastering process, these factors are examined in more detail and corrected if necessary.
Mastering not only requires new, but also old recordings, which either need a sound improvement due to their quality before a re-release (especially from analog master tapes) or for further releases in a new compilation. One then speaks of remixing (" remastering ")
In addition to the purely technical processing, mastering can often achieve a significant improvement in the sound impression of a music / sound production. Various technical equipment - such as filters , equalizers , compressors or psychoacoustic devices - is used for this.
The stereo base width can also be changed during mastering. This is achieved through the technique of so-called MS mastering, whereby the signal is separated into the middle and side signals. In this way, the level of instruments that are in the center of the panorama can be adjusted in relation to the instruments panned further out.
Depending on the requirements of the source material, mastering can include, among other things, noise reduction, level adjustment and pause harmonization of the individual tracks or the removal of digital jitter as well as the creation of fades .
After the actual audio mastering, premastering , which usually no longer involves sound processing, determines the track order, sets pauses and track indices, and creates certain additional information such as ISRC , EAN codes or CD-Text . Finally, a premaster CD is created that should conform to the Red Book standard for audio CDs. Before the time of hard disk recording and when only vinyl records were produced, these steps were accordingly not necessary or were only carried out by the press shop. Finally, a master tape was created that served as a template for the production of sound carriers in the press shop.
Digital and analog mastering
A distinction is made between digital and analog mastering. When it comes to digital mastering, processing is usually done entirely using computer technology and special audio software (so-called digital audio workstations ). All necessary devices known from conventional analog technology are available here as virtual machines in the form of so-called plug-ins . This mode of operation is the cheapest, but is subject to certain restrictions, especially in terms of real-time capability, which, due to the system, can never be fully achieved even with the most powerful hardware, as certain plug-ins cause the signal to be delayed. Therefore, in professional studios, external, DSP -based studio devices are preferably integrated into the signal path , in which the signal processing takes place in a similar way, purely mathematically - but completely in real time.
In analog mastering, on the other hand, the mastering engineer uses conventional analog devices that are integrated into the digital setup of today's studios via high-quality AD converters, so-called studio converters . By using real analog devices, one bypasses the artifacts of digital processing that sometimes exist : on the one hand, the mathematical models used do not map the analog components as precisely as desired, on the other hand the algorithms always represent a compromise between execution speed and accuracy But in no way inferior to role models. The digital replicas of the analog devices also have the advantage that the analog noise of the original hardware can be switched on and off at will. The fundamental disadvantage of analog technology compared to digital technology - namely, the unwanted addition of distortion and noise to the sound material - is not very problematic with high-quality equipment, but can also be used deliberately to give the audio material a characteristic sound. This mixed way of working, also known as hybrid technology , is the most expensive.
Due to the steadily increasing performance of computer technology, digital stand-alone hardware is also on the decline, especially since not a few manufacturers offer their software both in devices and as inexpensive plug-ins . The plug-ins even have an advantage in many cases: When the software calculates offline, they deliver a mathematically more exact result precisely because of the lack of real-time restrictions.
In addition to classic recording studios with their sound engineers, there are special mastering studios in which mastering engineers deal exclusively with the tonal adjustment and improvement of third-party recordings. Often, however, the customer's request for the creation of a loud end product is also fulfilled, which can only be done by drastically reducing the dynamics and transparency of the audio material. For the resulting problems, see Loudness War .
- Bob Katz: Mastering Audio - About Art and Technology . GC Carstensen Verlag, 2012. ISBN 978-3-910098-43-5
- Friedemann Tischmeyer: Audio mastering with PC workstations . Wizoobooks, Bremen 2006. ISBN 3-934903-52-5
- Georg Berhausen-Land: Entry into mastering . Practical course with DVD. Wizoobooks, Bremen 2007. ISBN 3-934903-60-6
- Florian Gypser, Karsten Dubsch: Mastering . (PDF; 1.1 MB) audio workshop, Waldorf 2007 (short version)
- Friedemann Tischmeyer: Tutorial DVD Audio Mastering Vol. 1 . Tischmeyer Publishing, Kükels 2007. ISBN 3-940058-05-X
- Friedemann Tischmeyer: Tutorial DVD Audio Mastering Vol. 2 . Tischmeyer Publishing, Kükels 2007. ISBN 3-940058-06-8
- Friedemann Tischmeyer: Tutorial DVD Audio Mastering Vol. 3 . Tischmeyer Publishing, Kükels 2007. ISBN 3-940058-07-6
- Bob Katz: Mastering audio - the art and the science . 2nd Edition. Focal Press, Burlington / Oxford 2007, pp. 210 ff . ISBN 0-240-80545-3