Difference in mastering for surround

Mastering is the process taken after the mixing stage and is the last process taken before the audio is ready for the market place. Mastering engineer’s will often compress and equalise all of the tracks for the album or E.P. to ensure that they all have a suitable dynamic and frequency range: this allows continuity from song to song. After this is done, the engineer will encode the audio to an appropriate format and this is where 5.1 and stereo music differs.

Unlike stereo in order for the consumer to be able to playback surround audio it must go through a different encoding process, this is due to the extra four channels that 5.1 surround sound utilises. Two common formats are used for encoding 5.1 audio are the Dolby Digital format (AC3) by Dolby Laboratories Inc. and DTS by Digital Theatre Systems Inc. AC3 by Dolby Labs is the mandatory format for DVD-V discs and can be encoded at up to 448kbps at a maximum resolution of 24-bit and 48kHz. Its alternative DTS can be encoded at up to 1536 kbps at a maximum resolution of 24-bit and 96kHz. These file formats have a greater resolution than CD quality (16-bit, 44.1kHz); this is because they were design for DVD purposes like film.

Although these formats were designed for DVD there is an audio CD that can replay surround audio, which is the Super Audio Compact Disc (SACD). This dual-layer disc offers 16-bit stereo, which is used for conventional CD’s and also a high-resolution six-channel mix. The benefit to this CD is that it can be played through normal CD players, however in order to playback the SACD in surround the consumer must use a SACD player or DVD player that supports SACD.