Making Anchor Bay's 'The Beyond' - A Visit with Complete Post's Mike Malooly

Easily one of the most complex and misunderstood aspects of the DVD format is the process of compression. But just what is it, and why does the format rely on it? In the first of our three-part series on Compression, Authoring and QC and the making of Anchor Bay's The Beyond, let's take a look at the art of compression. But in order to understand how it works and what role it plays in the entire DVD production chain, it is important to first take a brief look at the film-to-video transfer process, otherwise known as telecine.

The craft of transferring film to video remains a mysterious one to most DVD enthusiasts. How do all these small celluloid frames wind up on a strip of videotape, or buried deep inside the hard plastic mass of our beloved 5-inch disc? To accomplish this feat, literally every single frame of a film must be digitized (scanned in) one at a time, and all audio information digitally recorded and synched to the picture. And most, but not all, picture parameters are set during the telecine phase. Color balance, contrast, resolution and other image settings are carefully supervised by the telecine operator, in conjunction with the creative team. Audio elements are also mixed, EQ'd and sweetened before they are transferred from their original analog or digital source to the final composite master. The resultant film-to-tape transfer is stored on one or more of the common consumer-level video formats: 525-line NTSC video, PAL (for foreign markets) and, as is happening more and more frequently within the industry, high-definition. Once the master is made, the most common digital tape storage formats include D1, DigiBeta or DCT component digital tape, as we’ll as many others.

For DVD, once the telecine is completed and the NTSC master is ready to go, the material still has to be compressed before it can be stored on a disc. But with a full digital 525-line NTSC master created, why the need for compression at all? Because the telecine process is done in a 1:1 ratio, resulting in no loss in any video or audio information during the transfer, the resultant resolution (i.e., number of picture elements that make up an image, or the pixel count) of the final master is exceedingly large in size. Without any reduction in the amount of data, even advances in DVD disc storage technology (such as a DVD-9 dual-layer disc, which holds nearly 8.1GB of information) cannot hold more than a few minutes of uncompressed video and audio material.

So, the Moving Picture Experts Group (better known simply as MPEG) developed the MPEG-2 compression scheme, which was adopted as the standard codec for the DVD format. MPEG-2 allows a 525-line NTSC digital master to be reductively encoded and thus stored in a much smaller space than if it was simply transferred at a 1:1 ratio, pixel by pixel. But how can images so large in size be compressed in so small a space? How the MPEG-2 codec accomplishes this is by looking for redundant data; that is, information that does not change from frame to frame. It creates digital shortcuts in the form of commands to store this redundant information more compactly, thus reducing the total amount of space required. Then, the decoder (via any DVD playback device, such as your DVD set top player or DVD-ROM drive) understands and interprets those instructions to rebuild the image. It is this process of encoding and decoding that forms the first building block of MPEG-2 compression.

The Art of Compression

So how exactly is compression performed, and what does a compressionist do? The MPEG-2 compression process involves roughly three main phases: the initial encoding of the digital master, the fine tuning or "tweaking" of the material to maximize quality before final encoding, and working with other departments such as authoring and QC (Quality Control) to make any final adjustments as required

Throughout this process, interaction with the client is intensive, and with the ever-growing number of new DVD titles being produced, deadlines are often less-than-ideal. To be able to deliver the required content in the mandated timeframe, a compressionist needs to possess a mixture of technical, creative and initiative know-how. The process is long and arduous, and even tedious. The more complex the nature of the project and the number of elements involved, maintaining quality within a limited amount of disc space becomes a delicate balancing act.

To better understand the creative and technical challenges involved in the process, we sat down with Michael Malooly of Complete Post during the production of Anchor Bay's upcoming The Beyond special edition, to get a firsthand look at the entire process. With years of experience in the industry, Michael has worked in multiple areas of the overall DVD production, including quality control, telecine and now compression. Every decision a compressionist makes can seriously impact the quality of the final product, and although their role may only be one part in the overall chain of DVD production, a team is only as strong as its weakest link…

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