Introduction to Video Compression - A Practical Guide to Video and Audio Compression - page 6

an expensive mistake, then it has accomplished an important goal: to arm you with
enough knowledge to ask the right questions and understand the answers you get.

1.12 Testing, Testing, Testing

Test your own content on all the systems you are considering for purchase and prove to
yourself which one is best. Demonstrations are often given to potential customers under
idealized and well-rehearsed circumstances with footage that may have been optimally
selected to highlight the strengths of a product. I've been present at demonstrations like
this, and then when customer provided footage is tried, the system fails utterly to deliver
the same performance. Of course, sometimes the products do perform to specification and
well beyond, which is good for everyone concerned. There is no substitute for diligence
during the selection process.

1.13 Defining the Territory

If you are presented with a large meal, it is a good idea to start with small bites. Video
compression is a bit indigestible if you try and get it all in one go.
We need to start with an understanding of moving image systems and how they
originated. Early in the topic, we look at film formats since they have been around the
longest. It is also helpful to understand how analogue TV works. Much of the complexity
in compression systems is necessary because we are compressing what started out as an
analog TV signal.
We will use the metaphor of going on a journey as we look at what is coming up in
the various chapters of the topic.

1.14 Deciding to Travel

In Chapter 2, we will examine the content we want to compress and why we want to com-
press it. This includes the platforms and systems you will use to view the compressed
video when it is being played back. If you just want an overview of why compression is
important, then Chapter 2 is a good place to start.

1.15 Choosing Your Destination

In Chapters 3, 4, 5, and 6, we look at the physical formats for storing moving images. We
will examine frame rates, image sizes, and various aspects of film and the different ways
that video is moved around and presented to our video compression system. It is impor-
tant to know whether we are working with high-definition or standard-definition content.
Moving images shot on film are quite different from TV pictures due to the way that TV