Tutorial: Shooting Top-Quality Streaming Video—How to Minimize Motion
A version of this article first appeared in the September issue of Streaming Media magazine. For your free subscription, click here.
Welcome to the first installment of our Shooting Top-Quality Streaming Video tutorial series. We’ll begin by discussing how to minimize motion in your videos, but first, let’s take a brief look at the range of challenges you’ll encounter when you’re shooting for streaming.
Understanding the Landscape
Whether starting from scratch or coming over with loads of experience shooting video for broadcast, movies, or DVD, shooting video to produce top-quality streaming video has (at least) four unique requirements.
First, with most other types of videos, directors and producers are taught to introduce motion into the video to retain the viewer’s interest, so slow pans and zooms come almost naturally to most videographers. When shooting for streaming, however, motion negates the benefits of the inter-frame compression algorithms used in most streaming compression technologies, degrading the quality of the compressed video.
Of course, how much the video degrades depends upon the final production bit rate of the video and the codec used to compress it. This is shown in Figure 1, a short zoom sequence in an interview compressed to the same parameters with two different codecs. Looks great on the left, awful on the right.
Figure 1 (below): Some codecs handle a slow zoom better than others.
For this reason, before shooting, you’ll need to know which codec you’ll be shooting with and the target bit rate. In most instances, you’ll also have to reduce the amount of motion in the video to produce good quality streaming video, which I address in How to Minimize Motion for Streaming.
Second, you have to manage your backgrounds carefully. Codecs respond differently to different backgrounds, as shown in Figure 2. On the left, the image is clear; on the right, the background is slightly over-saturated and blotchy. Figure 2 (below): Clear on the left, blotchy on the right.
When producing your set, you have to know the idiosyncrasies of your target codecs to optimize your background, as well as understand how to dress and position your subjects. This will be covered in How to Design Your Set.
Lighting is the third key to shooting top-quality streaming video. Again, when shooting for broadcast or movies, producers use hard lighting to set moods and/or provide a certain look to the video, which produces shadows and regions with low lighting in the video. This look often produces artifacts and noise during compression.
For this reason, when shooting for streaming, you have two overriding priorities, first to provide sufficient lighting to avoid gain noise in the camcorder, and second to create adequate contrast between the subject and the background. I’ll cover how to do this in How to Light Your Set for Streaming.
The last step, of course, is the camera itself. Do broadcast cameras produce vastly better quality than the relatively inexpensive 3CCD cameras that most corporate producers use? Once you’ve selected your camera, which settings should you use, and do techniques like shooting in progressive mode increase the quality of your streaming video? I’ll cover issues like these in How to Optimize Your Camera Controls for Streaming.
A quick word about audio. Most producers of streaming video agree that the audio side of the equation is even more important than the video, that viewers expect and accept degraded video, but not audio. I agree, but will focus this series of articles on the visual side.
We begin this issue by focusing on reducing motion in your video. The most important point to remember while shooting is that any motion degrades video quality. The second point is that the amount of visible degradation relates to the data rate of the compressed clip, and the selected codec.