Dolby Digital

While the film side of things is going on, the audio is dealt with in a different fashion. There are a few types of film audio out there, mainly Dolby Digital, SDDS (Sony) and THX (Lucas). In each case the audio is processed and read differently. Each theatre must have the proper decoding equipment to play the sound back properly. We chose Dolby Digital because it had a wide adoption and was less expensive to license.

After paying the licensing fee to Dolby, they send out an engineer to create a MO (Magneto Optical) disk for each reel. He/she basically checks that the 5:1 mix is up to their standards and sets some levels/applies some filters. Typically at this stage the Dolby guy will want to make sure he is looking at a physical representation of each film out reel. This physical medium can be a Digital Beta tape output from the Quantel. The Dolby guys tend not to like QuickTime movies as they are not a "physical" reference such as a digital cut or a "dirty dupe" telecine of each reel's negative. They also use 2POPs on the film out reels and the audio mix to confirm lineup.

The MO disk is then used to create Dolby film strips for each reel. The final step is to marry the Dolby print and the master negative together to make your answer print (which is a interpostive). The Dolby information is written between the sprocket holes of the 35mm film on the answer print and is read by a decoder on the film projector. Here is a photo of what Dolby looks like.














If the audio on the answer print does not line up for whatever reason (which is common), then you adjust the relationship between the master negative and the Dolby strip and create a new answer print for that reel.