Better Livestreams

The number one way to improve the technology side of a livestream - sorry, technology can’t improve the content – is to improve the audio quality. The second most important contributor to video quality is … lighting! Let me quote from an article by Paul Alan Clifford, self-styled Pastor to Techies and ChurchTech consultant on the blog churchproduction.com.

God is much better at creating things that see than we are. Our eyes, for example, are a technical marvel. The dynamic range they see far exceeds what most cameras can. This one fact is why so many churches have such bad lighting.

What’s the problem?

It is often difficult to explain why it is that lighting is needed in environments where we can see perfectly well. Our eyes “see” far better than any video camera ever made. They have superior low-light performance, superior colour palette, superior focusing ability and superior resolution. Our eyes work so well, that it seems inconsequential to architects and lighting designers to include features in our buildings that are problematical (at best) in terms of delivering light to the things we want to look at. Large windows directly behind the pulpit and top-down vertically directed lighting are common issues in this regard. However, most of the time, our eyes automatically compensate for this, and we don’t notice – we even think the scene looks good!

Cameras, on the other hand, will “look” at that same scene and potentially struggle to produce a usable image. Let’s look at how a camera works. I’m going to walk through a typical electronic digital camera; in terms of lighting issues, a film camera has the same types of issues, though there are more options to mitigate these in the processing stage.

At its simplest, a camera is a device that controls the admission of light into a hole in a box, to illuminate a sensor/recording device. We enhance this by adding lenses and other modifying devices to give us more control over the image produced. With a digital camera, the light entering through the lens strikes an image sensor. The signal output by the image sensor is processed within the camera to create image data, which is stored in a memory. For motion, multiple images are compiled into a video stream and transmitted or stored.

In the camera, the image sensor is the equivalent of the human eye. It has the role of converting the light directed on it through the lens to the electrical signals that are processed by the image processing engine. Sensors inherently have dynamic range limitations - too much light will wash out the picture; too little light results in little or no image being recorded. Light can be regulated by the lens aperture, (the size of the opening in the camera’s lens), which can be adjusted to allow more, or less, light in. However, cameras always require more light to produce a given image compared to the naked eye. Even at its most open setting, a lens will not allow enough light in to produce an adequate image for livestreaming.

Camera manufacturers have traditionally responded to this issue by using the Image Processing Engine in the camera to attempt to compensate for the sensor shortcomings. The quality of the Image Processing Engine makes the difference between low-quality and high-quality cameras. The Image Processing Engine is a dedicated, special purpose computer that processes each image in the stream pixel by pixel. The workload for this computer increases as resolution, colour depth or frame rate increase – there are simply more pixels to process in a fixed timeframe. If the scene the camera is capturing doesn’t have enough light reflecting back to the camera, the Image Processing Engine has to work even harder and may run out of processing capacity all together, resulting in flat, sub-optimal images. Note that it is the reflected light we need – there may be plenty of light in the environment as far as the eye is concerned. The camera and the light source need to be on the same side of the scene for this to work. A window behind the scene will easily overpower the light reflected from the scene, and overhead lights will light the top of the scene and cast shadows down the scene which will turn up as dark patches in the video.

Solutions

The obvious and technically preferred solution is to put more light on the scene. However, there are less costly options that may help:

• Reduce the quality of the video output of your cameras (less resolution, colour depth, frame rate) to reduce the processing load on the Image Processing Engine.
• If you can relocate any of your existing lights, move them closer to the scene, and reduce the angle to the camera.
• Control natural lighting with blinds or curtains – even indirect sunlight will overpower other lighting. Also, if the sun goes behind a cloud in the middle of a livestream, you may suddenly find that what was working well, no longer works.

Theatrical Lighting

Theatrical lighting can be optimised to deliver targeted white light, to get great video, although it can be expensive to install. LED lighting systems have reduced the price of lighting dramatically and may provide an affordable solution. Some things to remember:

• Check your building’s electrical capacity. LED lighting has reduced the requirement for power significantly, but always check capacity.
• Check structural capacity if you are considering mounting lights from walls or ceilings. The Building Code will require secondary seismic restraint, so things don’t fall in an earthquake.
• The objective is to create an even wash of light over the full scene. This tends to require lots of light fittings, which is why 3-point lighting was developed. This identifies the areas of most interest in the scene and illuminates them with Key light (main light), Fill light (fills in the shadows from the key light) and Top light (sometimes called back light – this highlights the top and side of the subject so it visually “pops” out of the background). There are many good videos and articles on the web on how to install 3-point lighting.

Have fun experimenting with the tips I have shared to help improve your livestreams and videos.