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Jim Krause | Classes | C228 Multi-Cam TV Studio Production 1

Week 8

Agenda/Reality check/Updates -----------------------------------------

  • This week in lab:
    • Produce round two of Studio 7 Perspectives .
    • Pitch Dramatic/Comedic scenes.
  • Lab next week:
    • Quiz #3 (Studio tech & signal flow)
    • News Update exercise. Students must turn in a 30-second script (just the reporters copy- NO camera shots, etc.) and 2 graphics (location and over the shoulder). We need 2 volunteers per lab to serve as on-camera talent, which means looking "newsy" at least from the waist up. In lab this week you should pick at least two people from each lab for this. I'll cover the exercise in this lecture.
  • Performance videos - We need talent! This could be a musician (a solo or duo is suggested- no bands, as they are too complicated to mic.), a monologue, a comedian, or a comedy skit (E.g. Full Frontal, University Twits, etc.)
  • Don't forget to check in via Chat (for attendence)

Readings: Cybercollege 57 (timecode) & 60 (switchers)

Timecode, Video Switchers and Chroma Keys ------------------------

Timecode is a numerical code embedded into media, which allows for synchronization and frame accurate control. Timecode allows us to label and access a specific frame or location in the media stream precisely and with frame accuracy.

Timecode is formatted like a 24 hour clock HH:MM:SS:FF.

"Hours" range from 00 to 23, "minutes" range from 00 to 59, "seconds" range from 00 to 59, "frames" ranges from 00-29. The highest value timecode you can have is this:









If you added a single frame to this, you'd get "midnight," which is 00:00:00;00

Drop frame verses Non-Drop Frame Timecode - We think of video running at 30 frames per second, but it actually runs a tad slower: 29.97 frames per second. This 3/100ths of a second difference every second adds up and can cause timing issues if misinterpreted. This is why we have two different ways to count or number timecode (which can be set on the camcorder, edit software, or digital recorder):

  • Non-drop frame often referred to as "NDF"
  • Drop frame often referred to as "DF" (The industry standard for delivering TV/film content.)

Non-drop frame timecode: each new frame of video is given the next higher number. (06:01:00:29 becomes 06:01:01:00)

The problem with NDF timecode is that it's based on 30 frames per second, while video actually runs at 29.97 frames per second. The displayed timecode in the NDF format will eventually drift from the actual running time of a program.

Drop frame timecode is a little trickier to count, but provides a numbering system that is more accurate, and stays true to the running time of our video/film content.

You can tell when something is drop frame because the time code display has semicolons (;)

If you want to learn more, watch one of these videos:

If you want ta timecode calculator for you phone download one of these:

Or, if you want to access one on-line, try this one:

Signal Flow and Video Switchers

Signal Flow in the Studio - In a TV production studio you often hear the words "upstream" and "downstream." These terms use the analogy of water flow to represent the relationship of the video signal to various pieces of equipment in the studio.

Think of a camera as being the most upstream element in the studio. This is where the signal originates. After the signal comes out of the camera CCU, it flows downstream into the input of the switcher. Once inside the Grass Valley switcher in Studio 5, the signal flows from the Preview and Program busses to the keyer. So the keyer is downstream of the program bus. After the keyer, the video flows to the Master/Panic Black switch. So whatever we do on the Program or keyer stage can be covered by the Master/Panic Black button. After leaving the switcher, the video flows downstream to a VTR.

Video Switchers - Video switchers allow the user to select and mix video signals. They also provide a limited degree of effects. Basic functions include:

  1. Select appropriate source from several inputs
  2. Perform basic transitions
  3. Create/access special effects

Switchers can have a number of different busses. A buss is simply a row of buttons, which allow the operator to select which input goes out to a particular destination. Usually there are at least three different busses on a production switcher:

  • Program bus: whatever source is selected goes to the program monitor
  • Preview bus: identical in appearance to the program bus
  • Effects bus: used to select sources for different effects

Basic Operation:

  • Cut or take (Ready 1- take 1)
  • Flip flop of program/preview bus
  • Dissolve: (standby 1- dissolve to 1)
  • Super (superimposition: using the fade bar and keeping it halfway between sources)
  • Fade: (a dissolve with black)

Special Effects & controls:

  • Wipes & wipe patterns (see below)
  • Key & clip controls (chroma key, luminance key)
  • Downstream keyer
  • Color background controls

Wipe: when one image replaces or uncovers another
Soft wipe: you can set the border to be soft (fuzzy) by a knob on the switcher

Wipe pattern: the geometric shapes you can choose from (diamond, circle,) these are standardized and referred to by numbers so that EDLs (edit decision lists) can pull them up consistently from various switchers

Wipe positions and directions: al wipes can be reversed (by pressing the reverse button on the switcher) or stopped partway by stopping the fader bar.

Split screen: if you stop a horizontal, vertical or diagonal wipe halfway you get a split screen.

DVE (digital video effect) allows you to actually squeeze, rotate, flip, shrink or expand the image. Grass Valley uses the abbreviation IDPM (Digital Picture Manipulation) instead of DVE- but they both mean the same. DVEs or DPMs allow for shaping or distoriting the video in interesting ways, including perspective, squuezes, page turns, flips etc.

Keys: When using keys, the switcher replaces part of the video signal with video from another source. There are several types of keys you can do with a production switcher: luminance keys, chroma keys and external keys.

  • Luminance keys work on brightness. If someone is standing in front of a black background, you can use a luminance key, adjust the threshold, and key out the dark areas. Similarly you can key out the brightest areas of an image. The problem with this type of key is that it's not very precise. If we key out the dark areas, everything else that's equally dark will be removed as well (shoes, pupils in eyes, buttons, etc)
  • Chroma keys work by selecting and removing specific colors. This is usually how the weatherman standing in front of a map is produced, or "on-location" shots of news people who areen't really on-location. The two most popular colors to use are blue and green. This is because these colors are usually farthest away from the color of people's hair and skin. Studios and production companies usually have both a green and a blue screen. If the talent shows up wearing blue, you use the green screen and vice-versa.
  • External or Linear keys are fed by an external source, such as a character generator. The external device sends two video signals: the key and video fill. The key signal acts like a cookie cutter telling the switcher what video to remove. The video fill is what goes into the cut out portion.

Downstream Key - This is a key that happens downstream, or after the video leaves the switcher. These can be used to insert the station ID, weather warnings, etc.

Switcher types & functions

The Grass Valley switchers in Studio 5 and 7 are just one type of switcher. There are several different types of switchers designed for different applications.

  • Production switchers are used for live production. (like the Kayak Grass Valley swe have in Studio 5) & 7
  • Post-production switchers (used for primarily for editing) Most of the switcher's functions (such as wipes, dissolves, etc.) can be remotely controlled by the Editing Control Unit. These are now rare as most editing is being carried out with non-linear systems (Avid, Final Cut Pro, etc.).
  • Master control switcher: These are optimized for switching and controlling numerous video sources and playback devices (VCRs digital cart machines, etc.). These generally won't have a lot of effects but focus on video previewing and insertion of station IDs and weather warnings.
  • Routing switchers: Similar in function to a patch bay. Some routing switchers are nothing more than a row of buttons. Some are computer-based and can be programmed with a variety of setups.

Production Switcher

Master Control Switcher

Simple Routing Switcher

Don't forget Audio

Audio follow video switchers - Audio switching is sometimes done by a separate device (other than the video switcher) The term "audio follows video" refers to devices that control or trigger an audio switcher. The result is that when you swicth a video source, the audio follows along.

The Grass Valley Karrera Switcher

Our Karrera switcher has 3 Mixed Effects Banks (ME1, ME2, and the Program Bus).

This week you'll get a chance to learn how to use the "look ahead" feature this week in lab.


Karrera Keyer Features (video 4.5 minutes)

Lighting for a Chromakey



Lab --------------------------------------------------------------


  • Attendence
  • Get volunteers for next week's News Exercise (need to dress for delivering news).
  • Get suggestions for performers
  • Demonstrate setting up a chroma key in the switcher
  • Show the "look ahead" function in the switcher
  • Show the "PST BLK" function on the switcher
  • Carry out Studio 5 News Update


  • Take attendence
  • Make sure Demonstration Videos are scheduled for weeks 10 & 11.
  • Get suggestions for performers. Note what these are and make sure there is followup.
  • Walk through News Update script, Pick at least two people from each lab who can be on-camera talent.
  • Pitch Dramatic/Comedic scenes.
  • Produce round two of Studio 7 Perspectives.
  • Wrap



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