A few techniques can keep the quality of your broadcasts high.
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Before you save video to disk or transmit it, you compress the video. Codecs (encoder-decoders), which compress video, work best with clean input data. If the audio or video is muddy to start with, it remains muddy after compression. Some codecs might even exaggerate the imperfections of poor inputs. Before compression, make sure the media file contains high-quality audio, good lighting, and optimal broadcast settings.
You can make a good live event even better by paying attention to audio details. Here are some suggestions:
•Use an External Microphone Most video cameras have an audio input for an external microphone. Use this, whenever possible, instead of the built-in microphone. Built-in microphones usually are not high quality, and they tend to pick up hum from the electronics inside the camera. Even an average external microphone can deliver better sound than most built-in camera mics.
•Use a Microphone Splitter or Mixer If the broadcast has more than one sound source, use a separate mic for each sound source. Give each speaking subject a dedicated mic. Connect the mics to a mic splitter or audio mixer. Connect the output of the splitter or mixer to the camera audio input.
•Position the Microphone Properly Place any microphone as close to the sound source as possible, even when using omni-directional microphones, because sound volume decreases greatly the farther away the microphone is placed. High-volume sound hitting the microphone results in a stronger signal from the mic.
•Use Lapel Microphones Even inexpensive lapel microphones can make a huge difference because you can place them close to the source of the sound: the speaker’s mouth.
•Control Environmental Noise If a chair squeaks, use a different chair. If you have a wood floor and you can hear people shuffling their feet, put down a rug. Turn off air conditioners, machines, and buzzing fluorescent lights. Do whatever it takes to keep noise at a minimum. Microphones pick up everything. Before you start broadcasting, yell, “Quiet on the set!”
Do not underestimate the power of lighting. Whether shooting outdoors or indoors, you must control the light that hits the lens. For a good picture and a high-quality video signal, provide your lens two things: enough light and light with the right qualities. Here are a few suggestions for good lighting:
•If you use only one light source, don’t shine it directly on your subject. Diffuse the light by bouncing it off the ceiling, or by shining it through translucent material.
•Avoid deep shadows. Make sure you fill all areas of your subject with light. Sometimes this requires adjusting the light to bounce off a different wall. Alternatively, use two lamps. To light evenly, you can place one lamp low and another high.
•Allow soft shadows. Do not light too evenly. Good lighting usually has the brightest lamp above and to one side of the lens, aimed at the subject.
•If you pour too much light on your subjects, they will look washed out. If your lighting balance is excellent, you can avoid using much make-up on your subjects.
•Watch professional broadcasts and learn from them. As you watch, notice the lighting. Notice how directors employ the suggestions listed above.
Good lighting can make an amateur video look professional and a professional video look fabulous. One or two properly-placed lamps or reflectors can make a huge difference in the visual quality of your broadcast.
One advanced and very effective approach to good lighting is known as triangular lighting (or three-point lighting, or the three-light setup). This involves setting up three lamps (sometimes using the Sun as one of the light sources), in a configuration that separates the subject from the background. Here are the main elements of triangular lighting:
•Key Light (Main Light) Use the sun or your brightest lamp as your key light. It does most of the work. Place the key light higher than the talent eye-level and the lens, at least 20 degrees to the left or right of the line between lens and talent. This creates shadows on the subject that enhance the sense of three-dimensionality.
•Fill Light Use a diffused light source as your fill light. Place the fill lamp higher than the talent eye-level and the lens, on the side of the lens opposite the key light. If you place the key lamp to the left of your camera, place the fill lamp to the right, or vice versa. The fill light brightens the shadows, making them softer and less severe.
•Back Light (Rim Light) Place the lamp for back lighting behind and above the subject. Aim the back light at the top of the subject’s head until the head and shoulders of your subject are rimmed with light. The back light separates your subject from the background and enhances the sense of three-dimensionality. Good chroma-key requires sharp separation between the subject and background. Make sure light from the back light does not spill into the lens, causing lens flares.
Once you have good video and audio coming into Wirecast, make sure the broadcast settings are configured correctly for your presentation. Though there are many broadcast parameters to modify, there are three that are the most important: bandwidth, motion, and encoder settings.
Bandwidth is the speed of data transmitted from your computer to your viewers. Transmit data no faster than your network upload speed and no faster than the download speed of your typical viewers.
Estimate viewer download speed by the type of Internet connection they likely have. Are your viewers all on your corporate high-speed LAN, are they viewing from home via DSL or cable Internet, or are they on cell phones in remote areas? Set your broadcasting bandwidth accordingly.
If you broadcast to a LAN, discuss your plans with your network administrator. Verify that you will not disrupt the network with your broadcasts. Ask the administrator what your bandwidth upper limit should be.
See also Wirecast: Firewire and USB Cameras.
Once you determine your bandwidth, determine whether your video contains a lot of motion. An interview typically has little motion. A sports event, however, typically has lots of motion. Wirecast comes configured with defaults to help ease your configuration task. Choose a default configuration that meets your motion constraints.
It is beyond the scope of this document to describe the delicate balance required in defining encoder settings. Various streaming networks publish their optimal encoder settings. The Wirecast settings for the various streaming platforms generally are optimized for those platforms.
See The Encoder Presets Window for information on changing the encoder settings.