Video Feedback with Composite Cameras

A collection of info and resources for the course: "Intro to Video Feedback with Cameras" on Polyphase Portal. This is a community wiki; if you have a Polyphase login, you can edit or add to these pages if you feel so inspired.

🌀 Course Info

Course registration page: polyphaseportal.xyz/video-feedback-with-cameras

About the course

intro to video feedback with cameras

In this course, students will learn to create real-time visuals using camera feedback, and create recordings of the patterns they generate. We will each develop our own unique setup for generating video feedback patterns by pointing a video camera at a screen. While this method is simple at heart, it’s also very sensitive to small changes in conditions, and there are many factors that affect the resulting images, such as:

We will be working specifically with cameras and screens that support composite video, an analog video signal requiring just one simple cable (usually with either a yellow RCA or BNC connector).

Some prior experience in working with analog video signals is recommended for those who take this course, since you will need to provide and operate your own equipment. In an online course, there is a limit to how much tech support we can provide. However, there will be opportunities for troubleshooting guidance and Q&A during each class session.

Due to the nature of this medium, the resulting visual patterns we create will vary. Each student will have a chance to show their own setup and results so that we can all learn from each others’ experimentation!

Materials

Students in this course must have their own materials in order to participate fully. A document containing the full details on what you’ll need, and where to find it, will be sent out to everyone who registers.

Materials needed:

Optional but helpful:

About the Teacher

Paloma Kop is a multimedia artist who has been working with video since 2008. They have worked extensively with video feedback in their art practice & live performances, and hosted many in-person workshops through Phase Space and Phase Shift.

📹 Equipment & Materials

Analog Video Basics

The minimum equipment needed to get started with camera feedback is:

Though you can create a feedback loop with cameras and screens via other types of signals, such as HDMI, we are focusing on composite video in this class. Using an analog composite video signal allows us to incorporate other analog video equipment and tools into our feedback signal chain, and it allows us to use older, (sometimes) less expensive equipment.

Composite video usually uses a yellow RCA connector. Some professional video gear will have a BNC connector.

If your gear setup uses a mixture of RCA and BNC connectors, you can use a passive adapter to connect them together. However, if a device has BNC connectors, make sure they are definitely for composite video, because BNC is sometimes used for other types of signals as well.

If you are new to analog video, you should find out if your region typically uses the PAL or NTSC standard (or less commonly, SECAM). You will need to make sure that all your gear uses the same standard so that it is all compatible (some devices are able to switch between NTSC and PAL, either automatically or as a setting, and some only support one standard).

If you are curious, here is a list of resources where you can learn more about analog video (from the scanlines wiki). It is not a requirement for this class to have a deep technical understanding of analog video signals, so delving into this is optional.

Analog video resources

The primary goal here is that you can plug your camera into your screen, and the screen will show the live feed of what the camera is seeing. This basic setup is something you should be able to achieve on your own prior to the class. It is recommended that you have at least some experience working with analog video before this class, or be ready to do some learning on your feet.

If you happen to have access to multiple composite video cameras and screens, all the better. Different equipment can produce very different results, so experimenting to find what works best is a big part of the process.

A note about external links to products

I will try to add some links and models as examples of different equipment that can be used here. However, if you are purchasing equipment it is important to do your own research. Product links can be modified by sellers to show different products, inventory can run out, and prices can change, so we can't make any guarantees or simply point everyone to purchase the same items and rely on them to work. Be patient and know that finding the right equipment for video feedback often involves some trial and error. The up side to this is that since there is no one-size-fits-all solution, each of us will likely be working with different gear, and we will each get our own flavor of feedback as a result.

Buying older gear used is a great option, but we obviously can't provide links to specific listings since they are usually put up in small quantities. We encourage you to search on eBay, other used marketplaces, and/or at your local thrift/charity shop. Saving old gear from getting thrown away is often more sustainable than buying new equipment, and can sometimes be a much better value.

Cameras

Below are some of the types of cameras that can be found with live composite video output.

Security cameras

Many CCTV cameras have a composite video output. These can be great because they usually output a clean video feed. Some may be small and come in a dome-like enclosure; these will usually have a fixed wide-angle lens, and sometimes an infrared LED array for night vision. Others are larger and rectangular; these usually have a c-mount for attaching any compatible c-mount lens.

Examples:

Older consumer camcorders

Many camcorders from the 80s and 90s have a composite video output, though some require a specialized cable to access it. Some of these types of cameras have text or icon overlays on the video output, but it is sometimes possible to turn this off and get a clean output. Some even have digital effects.

Examples:

Mini cameras

there are a number of tiny cameras out there with composite outputs, which are sometimes used as backup cameras for cars, or other uses where they are built into some other device. These can be found brand new online for very cheap, but they usually have a lens that you can't change (often quite wide-angle) and no control over any of the settings (focus, exposure, etc.)

Examples:

Screens

CRT TVs

CRT screens are beloved for their retro aesthetic, and due to the technology behind them, they are extremely low-latency, which means your feedback patterns will often move and change very fast. Whether you are using them with a camera for feedback or for rescanning, it is helpful to use a camera that allows manual shutter speed so that you can set it to 1/60 for NTSC or 1/50 for PAL to prevent weird sync issues. But, some cameras without manual controls will still play nicely with CRTs; you will need to test them to find out.

Some CRTs don't take composite input and can only be used with an RF modulator.

They are also very heavy, take up a lot of space, and should be handled somewhat carefully due to the glass tubes.

LCD TVs

LCD screens can yield very good results when used for feedback. Their higher latency can actually make them a bit easier to work with. They can be found in small sizes made as backup screens for cars (often without an included power supply). TV models in the 15-20 inch size range with a variety of inputs can also be found used or in the trash.

Examples:

Tripods & Camera Supports

It's important to be able to control and stabilize the position and angle of your camera relative to the screen. On a budget, it is possible to create DIY camera supports out of a variety of household objects, such as small tables, books, etc. However, it can be very helpful to gather some specialized equipment to give you a finer grain of control. Here are some examples:

Projectors

You can also use a projector to create a video feedback loop. This can open up a lot of possibilities: projecting on different objects and surfaces, placing items or people in the path of the projector, and if you have more than one projector you can even layer their images together. Many consumer-grade projectors, even newer ones, come with an RCA input for composite video. However, they can also be expensive and delicate devices. Though we will be mainly focusing on using screens to create feedback, bear in mind that using a projector for feedback is also a great option, and try it out if you have one available to you.

👁️ Getting Started

Once you have your equipment, you are ready to get started creating some video feedback!

  1. Connect your camera and screen together so that the screen is showing what the camera sees, then point the camera at the screen.
  2. Try to align the edges of the camera's view with the edges of the screen, so they are lined up as closely as possible. You will likely have to zoom or adjust the distance between the camera and screen, as well as ensuring that the camera is level with the center of the screen, and pointing straight at the screen.
  3. Spend some time with your camera and screen, and identify what settings you can change that will affect the image (see below).
Settings to look for identify & experiment with on your camera and screen:
These controls may be available in the form of a knob, a lens ring, or an option inside a menu. For some security cameras, it may even be a small plastic screw called a "trim pot." Not all cameras and screens have all of these settings, but the more of them you can find, the more control you'll be able to have over your feedback.

Start by trying to align the camera and the screen as best you can, get the screen in focus, and try to get as close to neutral color & brightness as you can. From there, you can start to change individual settings and see if it affects the resulting feedback. Feedback can be delicate, so start with small changes.

It can be helpful to work in a darkened room as any ambient light can affect the results.

🔮 Optical Manipulation

What is optical manipulation?

Transformations & Geometry

rotation

tripods

magic arms

gimball heads

Physical materials

putting the tv flat on the table

Prisms and lenses

dichroic

random glass

Mirrors and reflective materials

Filters

Polarizing film

Masking and silhouettes

Hands

Random objects from the kitchen or around the house, cool-shaped pieces of metal, toys

Movement - rotation, turntables

Images drawn on transparency film

 

 

to-do:

⚡️ Signal Manipulation

what is signal manipulation?

 

[note: add diagrams]

Video Processors

x

enhancers

Video Mixers

x

luma key

Advanced signal chains

figure 8 feedback

🎞️ Capturing & Rescanning

Now that you have a beautiful video in the analog realm, how do you get it into a digital file?

Since this topic is relevant to anyone working with analog video signals, it has been made into its own wiki.

→Capturing & Rescanning Analog Video

💡 Inspiring Works & References

Videos

^an article about this piece

Readings

History