Module 8: The Display, Monitors and Timecodes

VIDEO COLOR SYSTEMS

Color Systems

Be sure to read How Color Is Recorded, p. 16, and Thinking About Camera Choices, Compression, and Workflow, p. 94, before reading this section.

All digital camcorders accomplish the same basic set of tasks: (1) capture an image to a sensor; (2) measure the amounts of red, green, and blue light at photosites across the sensor; (3) process and store that data; and (4) provide a means to play back the recording, re-creating the relative values of red, green, and blue so a monitor can display the image.

Fig. 5-14. RGB, component, S-video, and composite video systems vary in the paths they use to convey the video signal from one piece of equipment to another. For systems that use multiple paths, the signal is sometimes sent on multiple cables, but often the various paths are part of one cable. See text. (Robert Brun)

Different cameras use different methods, particularly when it comes to steps 2 and 3. As noted earlier, each photosite in a digital camera sensor can measure only brightness, but we can create color values in the image by placing a microscopic red, green, or blue filter over individual photosites (a technique used for single-sensor cameras; see Fig. 1-13) or by splitting the light from the lens into three paths using a prism and recording with three sensors (the technique used in three- chip cameras; see Fig. 1-14).

Let’s briefly review how digital cameras acquire and process color; one or more of these methods may be employed by your camera.

RGB

All digital cameras internally process raw data from the sensor(s) to generate three distinct color signals—red, green, and blue (RGB). RGB (also called 4:4:4; see below) is a full-bandwidth, uncompressed signal that offers a wide gamut of hues and is capable of very high image quality. RGB output can be found in high-end cameras, including some digital cinematography cameras, and is usually recorded to a high-end format like HDCAM SR. RGB requires high bandwidth and storage space; it is particularly useful for visual effects. RGB handles brightness values differently than

component video, so there may be translation issues, for instance, when moving between the RGB color of a computer graphics program and the component color of a video editing program (see Fig. 5-12).18

Most digital cameras today record component video. They acquire the three RGB signals from the sensor(s), digitize them, process them, then throw away either half or three-quarters of the color data to make a video signal that’s easier to store and transmit. Prior to output, the three color signals (R, G, and B) are encoded into a monochrome luminance (sometimes called luma) signal, represented with the letter Y, which corresponds to the brightness of the picture, as well as two “color difference” signals (R minus Y, B minus Y), which are called chrominance (or sometimes chroma). Your color TV later decodes the luma and chroma signals and reconstructs the original RGB signals. Prominent examples of this type of video are the world standards for standard definition, ITU-R 601, and high definition, ITU-R 709.

Shorthand for component video is variously Y’CBCR, YCbCr, or Y,B-Y,R-Y. Though historically inaccurate, it’s also widely referred to as YUV. Analog component is Y’PBPR.

S-video (separate video) is also called Y/C. This is for analog video only, and it’s not so much a video system as a two-path method of routing the luminance signal separately from the two chrominance signals. It provides poorer color and detail than true component video, but is noticeably better than composite. If a camera or monitor has an S-video input or output, this is a superior choice over a composite input or output.

Analog television, the original form of video, was broadcast as a single signal. What was uploaded to the airwaves was composite video, in which the luminance and two chrominance signals were encoded together. As a result, composite video could be sent down any single path, such as an RCA cable. Many different types of gear today still have analog composite inputs and outputs, often labeled simply “video in” and “video out” (see Fig. 14-13). These can be handy for, say, monitoring a camera on a shoot. Composite video was used for decades for analog broadcast PAL and NTSC, but it delivered the lowest-quality image of all the color systems, with many sacrifices in color reproduction due to technical compromises. No digital cameras today record composite video.

See Reducing Color Data, p. 17, before reading this.

When we look at the world or a picture, our eyes (assuming we have good eyesight) can perceive subtle distinctions in brightness in small details. However, the eye is much less sensitive to color gradations in those same fine details. Because of this, smart engineers realized that if a video system records less information about color than brightness, the picture can still look very good, while cutting down the amount of data. This can be thought of as a form of compression.

As discussed above, most digital camcorders record component color. In this system there are three components: Y (luma) and CB and CR (both chroma). When the signal from the camera’s sensor

is processed, some of the color resolution is thrown away in a step called subsampling or chroma subsampling; how much depends on the format.

To see how this works, look at a small group of pixels, four across (see Fig. 5-15). In a 4:4:4 (“four-four-four”) digital video system there are four pixels each of Y, CB, and CR. This provides

full-color resolution. Component 4:4:4 is used mostly in high-end video systems like film scanners. (RGB video, described above, is always 4:4:4, meaning that each pixel is fully represented by red,

green, and blue signals.)19
In 4:2:2 systems, a pair of adjacent CB pixels is averaged together and a pair of CR pixels is

averaged together. This results in half as much resolution in color as brightness. Many high-quality component digital formats in both standard and high definition are 4:2:2. This reduction in color information is virtually undetectable to the eye.

Some formats reduce the color sampling even further. In a 4:1:1 system, there are four luma samples for every CB and CR, resulting in one-quarter the color resolution. This is used in the NTSC

version of DV. While the color rendering of 4:1:1 is technically inferior to 4:2:2, and the difference may sometimes be detectable in side-by-side comparisons, the typical viewer may see little or no difference. Another type of chroma sampling is 4:2:0, used in HDV and PAL DV. Here, the resolution of the chroma samples is reduced both horizontally and vertically. Like 4:1:1, the color resolution in 4:2:0 is one-quarter that of brightness.

Some people get very wrapped up in comparing cameras and formats in terms of chroma sampling, praising one system for having a higher resolution than another. Take these numbers with a grain of salt: the proof is in how the picture looks. Even low numbers may look very good. Also, bear in mind that chroma sampling applies only to resolution. The actual color gamut—the range of colors—is not affected.

The main problems with 4:1:1 and 4:2:0 formats have to do with the fact that after we’ve thrown away resolution to record the image, we then have to re-create the full 4:4:4 pixel array when we want to view the picture. During playback this involves interpolating between the recorded pixels (essentially averaging two or more together) to fill in pixels that weren’t recorded. As a result, previously sharp borders between colored areas can become somewhat fuzzy or diffuse. This makes 4:1:1 and 4:2:0 less than ideal for titles and graphics, special effects, and blue- or green-screen work (though many people successful do green-screen work with 4:2:0 HD formats). Often projects that are shot in a 4:1:1 format like DV are finished on a 4:2:2 system that has less compression.

Fig. 5-15. Color sampling. In a 4:4:4 system, every pixel contains a full set of data about brightness (Y) and color (CB and CR). In 4:2:2 and 4:1:1 systems, increasing amounts of color data are thrown

away, resulting in more pixels that have only brightness (luma) information. In 4:2:0 systems, pixels with Y and CR alternate on adjacent lines with ones that have Y and CB (shown here is PAL DV; other

4:2:0 systems use slightly different layouts).

See Camera and Recorder Basics, p. 5, and Viewfinder and Monitor Setup, p. 105, before reading this section.

On many productions, a lot of attention and money go into finding the best camera, doing good lighting, creating artful production design, etc. All in the service of creating a picture that looks great and captures the intent of the filmmakers.

But when showing the work in video, all that care can be undone by a display device that’s not up to the task. There are numerous reasons why a given monitor or projector may not show the picture the way it should (see below). As a moviemaker, you can control some aspects of the viewing experience (such as what type of equipment you use yourself and how you set it up). In screening situations, always do a “tech check” beforehand to make sure anything adjustable is set correctly. Unfortunately, once your movie goes out into the world, you have no control over how it looks and viewers will see something that may or may not look the way you intended it.

Types of Displays

These days, video displays are everywhere and there are many different types. The following are some of the main varieties available. Many of these technologies come in different forms: as flat- panel screens (except CRT) and video projectors (which shine on a screen like a film projector). CRTs are analog; the rest are digital.

Fig. 5-20. Sony’s Luma series of professional LCD video monitors. (Sony Electronics, Inc.)

 CRT

Cathode ray tube (CRT) technology is what’s behind the traditional TV set dating back to the beginning of broadcasting (see Fig. 5-6). For decades CRTs were the only game in town; now they’re no longer made. Even so, high-quality CRTs continue to offer some of the best color and contrast reproduction of any monitors. Color and brightness are formed by a coating of phosphors on the inside of the tube that glows when struck from behind by a scanning electron beam. CRTs, as a result, are a direct light source.

LCD

Liquid crystal display (LCD) monitors use a fluorescent or LED backlight to project through a screen of liquid crystal molecules sandwiched together with tiny RGB filters. The brightness of a pixel is controlled by sending a voltage to it, which darkens it to prevent light from shining through. LCDs are very thin and can offer good color reproduction; good blacks are a problem, though, and shadow detail may be crushed. Contrast, however, is constantly improving and major broadcast manufacturers are beginning to introduce reference-quality LCD video monitors (see below).

LCDs are often limited in their viewing angle: if you sit off axis (to the side, above, or below) the image may grow lighter or darker. LCDs have no burn-in effect (see Plasma, below).

PLASMA

Plasma screens are flat-panel displays that use tiny red, green, and blue pixels filled with a rare gas that gives off light when excited with electricity (similar to fluorescent light). Plasma screens can be very large, with a wide viewing angle. They have good contrast, color, and black levels. They use the same types of phosphors as CRTs and share a similar color reproduction. They are heavier than LCDs.

Some plasmas can suffer from screen burn-in, which causes the screen to retain brightness values from static images held for a long time.

OLED

Organic light-emitting diode (OLED) displays are another newer thin-film display technology that may someday replace LCDs. When an electrical current is applied, OLEDs phosphoresce (glow), providing their own illumination. They offer excellent color and contrast and have perfect blacks, since black is simply the absence of illumination. (Nothing is backlit.) Their

image-forming surface is paper-thin, and they can be remarkably light in weight.

DLP

Digital light processing (DLP) displays use millions of microscopic mirrors to direct light through colored filters. The mirrors switch on and off thousands of times a second. DLP projectors are capable of excellent color, contrast, and resolution; some are very affordable and compact. Many digital cinema projectors in commercial theaters are DLP.

Fig. 5-21. Panasonic 3D home theater projector with 1080p resolution. The PT-AE7000U uses transparent LCD panel technology. (Panasonic Broadcast)

OTHERS

LCOS (liquid crystal on silicon) is similar to LCD technology and is used for video projectors as well as camera viewfinders. JVC calls its version D-ILA and Sony calls its SXRD. LCOS eliminates the screen door effect created by visible pixels. (On some LCDs, the pixel grid is obvious in the image, as though viewing through a screen door.) Sony has a 4K SXRD projector popular for digital cinema use. Laser-based projectors are under development.

Clearly there are numerous display technologies in use. As a moviemaker, you need to be aware that, even within one type of technology, all monitors are not created equal and you need the right type for the job you’re doing.

Computer monitors are designed to show the output of a laptop or desktop computer. Depending on the system, computer monitors may be connected with a DVI (Digital Video Interface) cable, DisplayPort cable, Thunderbolt cable, or HDMI cable (see p. 237 for more on these connections). You’ll be using a computer monitor as part of your nonlinear editing system (either built into a laptop or connected to a desktop). Computer monitors operate in RGB color space (see above) and are fine for viewing the editing interface and controls. However, when it comes to evaluating the color and contrast of the actual video you’re making, other considerations come into play. Almost all broadcast video formats produced by HD and SD cameras are in component video color space (also called Y’CBCR or YUV; see p. 209). So if you edit your movie with an NLE and output the component signal

to a typical computer monitor, the picture will often look flat (low contrast) and too dark, because the color and tonal values are not properly converted from component to RGB (see Fig. 5-12). This problem can be addressed in a number of ways.

Fig. 5-22. When editing video, it’s important that tonal values be correctly translated from the editing system any built-in or external monitors. Shown here, Avid Nitris DX input/output and monitoring interface. (Avid Technology, Inc.)

First, if you’re producing something that will be seen only on the Web, cell phones, iPods, or computer monitors, then your computer monitor can serve as a picture reference, since your audience will be watching on RGB screens themselves. If you’re using a good-quality monitor and the picture looks okay to you, it will hopefully look somewhat similar for your viewers. You may need to color-correct your material in the NLE for proper contrast and color.

However, if you’re doing something for television or distribution in video (for example, on DVD or Blu-ray), you need to view the picture with proper component color values (for HD, the monitor should be compliant with Rec. 709). This is usually done with a monitor designed and calibrated for video use. A broadcast monitor is essentially a professional-quality video monitor capable of reproducing the full range of color to meet broadcast standards, with the kinds of controls and settings necessary to adjust the image properly. One particularly helpful control is the blue-only switch for accurate color adjustments (see Appendix A). Consumer TVs generally do not deliver consistent, controlled results; only with a broadcast monitor can you make the most realistic and accurate assessment of what the picture actually looks like. When doing critical tasks like color correction, a high-end reference monitor is even better.

You can feed a video monitor with the output from a camera, a deck, or a computer input/output (I/O) device. For example, you can output component video from an NLE using products such as Blackmagic Design’s DeckLink or Intensity cards, AJA’s Kona cards or Io boxes (see Fig. 14-4), or Matrox’s MXO2 I/O devices (see Fig. 5-23). Some of these can be used with a desktop computer via a PCI card, or connected to a laptop via Thunderbolt or ExpressCard. The MXO2 units have a calibration utility that can help you set up a consumer TV that lacks the ability to display color bars with blue-only (see Appendix A). This utility also allows you to calibrate an RGB computer monitor to emulate the look of a YUV video monitor. Matrox promotes this as an affordable alternative to a broadcast monitor for HD color correction.

Newer versions of some NLEs, such as Adobe Premiere Pro CS6, claim to display HD video properly on the NLE’s computer monitor (the desktop), so you may be able to view the picture with correct tonalities for TV without the need of an I/O device. However, I/O devices with dedicated video monitors may still offer better motion or quality, as well as larger full-screen playback.

Maddeningly, even if everything is set up correctly, you’ll find that your video often looks quite different on different systems.

Flat-panel displays have a fixed number of pixels, which is their native resolution, and they are at their best when playing video that has the same number of pixels (sometimes called pixel-for-pixel, or 1:1): for example, a 720p monitor displaying a 720p picture from a Blu-ray player. Check your monitor’s manual for its native resolution; when working in HD, try to get one capable of “Full HD” (1920 x 1080).

If the video source has fewer pixels than the monitor, the picture may be displayed pixel-for-pixel, using only part of the screen and appearing as a smaller box within the frame. Or the monitor may scale up (enlarge) the picture to the monitor’s size. Sometimes you have to do this manually (by pressing the zoom button on the remote). Scaling up an image will result in a less sharp picture.

If the video source has a higher resolution (more pixels), some detail will be lost and some of the picture area may actually be cut off. There are various devices that can convert from one format or resolution to another for monitoring. For example, if you’re editing HD video and only have an SD monitor, you can use capture cards or external boxes that can downconvert to SD in real time (see p. 550), though editing HD in SD is not optimal.

Flat-panel displays and digital projectors are progressive by nature. If you input interlaced video, the player or monitor will deinterlace, which may cause artifacts (see above). The other side of that coin is that if you shoot in an interlaced format, there can be interlace artifacts (such as twitter), or errors in field order (due to mismatched cameras or improper NLE setups) that appear only on an interlaced CRT display. So if you have only a progressive LCD or plasma screen there could be image issues you won’t see but others with CRTs may.

Newer flat-panel displays may offer high scanning rates, such as 120 Hz or 240 Hz in NTSC countries, which may reduce motion artifacts (see p. 86). Be aware that sometimes these have settings that create new, interpolated frames between existing frames (essentially increasing the frame rate), which can change the look of the video.

Getting accurate color reproduction is one of the trickiest aspects of monitors and projectors. There are two aspects you need to be concerned with. One is hue, technically called phase, which is like dialing into place all the colors on a color wheel. The other aspect is saturation—how pale or rich the colors are—which is controlled by the chroma setting. See Appendix A for setup.

If you’re working in HD, you’ll want the monitor set up to Rec. 709 standards for color and contrast (see p. 195). Many consumer monitors come from the factory set too bright and with oversaturated colors because consumers are thought to like a punchy image. In some types of video or connections there is no need for phase adjustments, such as when using HDMI, HD-SDI, component analog RGB, or PAL. However, small errors in hue adjustment will throw off analog NTSC colors in a big way. Also, when using an NTSC standard definition monitor to display HD downconverted to SD, phase should be adjusted.

Some devices, such as the Matrox MXO2 boxes, can help you calibrate a monitor, especially helpful with a consumer monitor that lacks a blue-only mode.

Some newer, high-end digital reference monitors claim to be able to reproduce colors accurately and consistently over time and from monitor to monitor without adjustment. The need for this kind of standardization can’t be overstated. As things stand now, many monitors and projectors you encounter will be poorly adjusted, and many aren’t even capable of reproducing all the colors in your video. But until the world is brimming with perfect digital monitors, keep those color bars handy.

Fig. 5-23. Matrox’s MXO2 family offers a range of input/output (I/O) and monitoring options to use with editing apps like Adobe Premiere Pro, Apple Final Cut Pro, and Avid Media Composer. Various models offer I/O via HDMI (RGB or Y’CBCR), HD-SDI, SDI, and other connectors. The HDMI

calibration utility lets an RGB monitor perform like a broadcast HD video monitor with proper display of Rec. 709 component color space so it can be used for color grading. (Matrox Electronic Systems, Ltd.)

The range from the darkest black to the brightest white that a monitor can reproduce is critical (see Understanding and Controlling Contrast, p. 191). Manufacturers express this as a contrast ratio, such as 800:1. The higher the better, but be skeptical of the numbers in the ads; they are often fudged.

Be sure to set black level (brightness) and contrast as described in Appendix A. The screening environment also plays a role in contrast. If there’s too much light in the room (and on the screen), you won’t get a good black. If the room is totally dark, contrast may seem harsh. A dim ambient light often works best with consumer monitors.

Playing widescreen video on a nonwidescreen monitor, and vice versa, can cause issues. This is affected by the monitor and how the video itself is prepared (see p. 74). Another consideration is whether the video and the monitor both use square or nonsquare pixels (see p. 232). Sometimes consumers choose to stretch the width of an SD 4:3 image on an HD 16:9 monitor, so it “fills the frame,” but this results in a distorted picture. Don’t do it!

Often video recorders and players offer a variety of output options through different connectors. For example, a player might have both composite and component outputs. Always use the highest-quality signal path possible. See Video Color Systems, p. 207, for a ranking of some of the options you may have. If the monitor has digital inputs, it’s preferable to go digital out from the player to the monitor rather than using analog connections. For example, use a DVI connection or an HDMI connection, which supports uncompressed video and audio between player and monitor or other gear. However, with some equipment, direct digital connections are not available. See p. 237 for more on digital connections.

Professional monitors often allow you to loop through the signal—going into the monitor and out to another monitor or recorder.

Fig. 5-24. Timecode. Shown here burned in on screen (also called a window burn).

The idea of timecode is simple: to assign a timestamp to every frame of picture or sound. Timecode is a running twenty-four-hour “clock” that counts hours, minutes, seconds, and frames (see Fig. 5-24). Timecode enables many different aspects of production and postproduction and is pretty much essential for serious video and audio work. Timecode comes in a few different flavors, which can sometimes be confusing.

In all types of video timecode the frame count depends on the frame rate you’re working in.

For example, when shooting at 30 fps (either 30p or 60i), timecode can advance as high as 23:59:59:29 (twenty-three hours, fifty-nine minutes, fifty-nine seconds, and twenty-nine frames). One frame later it returns to 00:00:00:00. Note that since there are 30 frames per second, the frame counter only goes up to :29. This timecode system is called SMPTE nondrop timecode. Many people just refer to it as SMPTE (pronounced “simpty”) or nondrop (often written ND or NDF). This is the standard, basic timecode often used in North America and places where NTSC has been standard.

In Europe and other parts of the world where PAL video has been standard, video is often shot at 25 fps (25p or 50i). Here, EBU timecode is used, which has a similar twenty-four-hour clock, except the frame counter runs up to :24 instead of :29.

One of the joys of video in NTSC countries is that with several formats, the frame rate is just slightly slower than what you might think it is (by 0.1 percent). For example, 30 fps video is actually 29.97 fps (which is to say, 60i is really 59.94i). When you shoot 24p video, that usually means 23.976p. This is described on p. 14.

You can’t see the 0.1 percent reduction in speed, but it affects the overall running time of the video. Say you watch a movie shot at 29.97 fps that has nondrop timecode, and click a stopwatch just as it begins. If you stop the stopwatch when the video timecode indicates one hour, you’d see that actually one hour and 3.6 seconds has gone by. The nondrop timecode is not keeping real time. This discrepancy is no big deal if the movie is not intended for broadcast. Nondrop timecode is often used for production.

Because broadcasters need to know program length very exactly, drop frame (DF) timecode was developed. This system drops two timecode numbers every minute so that the timecode reflects real time.20 A program that finishes at one hour drop frame timecode is indeed exactly one hour long. With drop frame timecode, no actual frames of video are dropped and the frame rate doesn’t change. The only thing that’s affected is the way the frames are counted (numbered). This is a point that confuses many people. Switching a camera from ND to DF has no affect on the picture or on the

number of frames that are recorded every second. The only thing that changes is the way the digits in the timecode counter advance over time.

Television-bound programs in NTSC countries are usually shot with DF code (though see note about 24p below). Even if you shot NDF you can edit in DF (most editing systems can display whichever you choose) and broadcasters will require that you deliver in DF because program length must be precise. DF timecode is usually indicated with semicolons instead of colons between the numbers (00;14;25;15) or with a semicolon just before the frame count (01:22:16;04).

If you’re shooting and editing at 24p frame rate, you may be using 24-frame timecode (the frame counter goes up to :23).

When shooting, you generally want to avoid drop frame timecode in 24p mode because the dropped timecode numbers can make it harder to do pulldown removal in the editing system. Cameras that use pulldown to achieve 24p often will not record DF for this reason.

Most digital video cameras generate timecode in some form. The timecode may be embedded in the video recording, or it may be included with the digital video file as metadata (see p. 242).

One way to record timecode is to embed the data in each video frame, outside the picture area. This is vertical interval timecode (VITC, pronounced “vit-see”). One advantage of VITC for tape recording is that it can be read by the VTR even when the tape is not moving (useful for editing). VITC does not use up any audio tracks but must be recorded at the same time as the video and cannot be added later (except during dubbing to another tape).

On some videotape formats, there is a longitudinal track (LTC) just for timecode. With some video decks, the LTC is readable during high-speed shuttle but VITC isn’t. Some formats allow you to record timecode on one of the audio tracks.

Consumer digital camcorders don’t offer professional SMPTE timecode but they do record a nondrop record run (see below) HOUR:MINUTE:SECONDS:FRAME for each frame of video, located in the data section of video tracks on tape or as metadata in the case of files. Fortunately, NLEs can read and manipulate this timecode as if it were SMPTE timecode. Mostly there is no way to preset anything. In the case of tape, like HDV, timecode in a consumer camcorder resets to 00:00:00:00 whenever a tape is changed or ejected. In the case of file recording, run a few tests with your consumer camcorder and import them into your NLE. It’s the only way to know if the native timecode is adequate to your needs.

Late-model DSLRs popular for HD work may also have timecode capabilities.

While digital consumer cameras offer no control over timecode, all professional cameras and many prosumer models allow you to preset the starting code and may offer a choice of timecode options. Different productions call for different choices, and methods can be somewhat different with tape-based or file-based recording.

The simplest timecode mode is called record run, which advances whenever the camera is recording. When shooting in record run mode, you can stop and start the camera as much as you want, but the code should advance on the tape or memory card uninterrupted from beginning to end.21

On most professional and prosumer cameras you can preset timecode to select the starting code. If you are using tapes or memory cards that store less than an hour of material, you might start the first at one hour (1:00:00:00), then start the second at two hours (2:00:00:00), and so on until you reach hour twenty, then start at hour one again. That way, the timecode on each tape and card is different, which helps keep things organized in editing. However, as long as you keep track of each tape or memory card, having two with the same code isn’t a big problem (and it’s unavoidable if you shoot a lot of material on a project). Many cameras allow you to set user bits (U-bits), which are a separate set of data recorded with the timecode and can be used to identify camera roll numbers, the date, or other information. It helps to use U-bits if the timecode on any two tapes is the same.

On some cameras, you can shoot with a time-of-day (TOD) clock recorded as timecode. TOD code can be useful if you need to identify when things were filmed or when more than one camera is shooting at the same time. A similar system is sometimes called free run mode, which advances every second whether the camera is running or not, but can be set to start at whatever number you preset.

TOD code can create a number of issues, which are explained below in Avoiding Timecode Problems. One issue is that TOD code is discontinuous whenever you stop the camera (because when you start up again, it will jump to the new time of day). Another problem can occur if you’re shooting tape and you record the same tape on different days. Say you finish the first day at four in the afternoon (16:00:00:00 code). You start the next day at eleven in the morning (11:00:00:00 code). When you edit this tape, the edit controller will find the lower code number after the high number, causing problems. Using TOD code will likely result in several tapes having the same code numbers, so try to put the date or tape number in the U-bits. You can avoid some of these problems with camcorders that have a real time mode that puts the time of day in the user bits (if you need it for reference) but uses record run mode for the regular timecode.

RED cameras can record two independent timecode tracks: “edge code” is SMPTE code that starts at 1:00:00 at the first frame of each piece of digital media (and is continuous between clips); “time code” is TOD code (or external free run code from another source) that is discontinuous between clips.

On productions when a separate audio recorder is being used, it will facilitate editing if the camera and recorder have the same timecode. For more on this, see p. 464.

On shoots when more than one video camera is being used at the same time, it’s also helpful if they’re operating with the same timecode. With cameras that can generate and accept an external timecode source, one technique is to run a cable from the timecode-out connector of one camera (the master) to the timecode-in on the second camera (the slave). Some cameras can import timecode via the FireWire connector. The master camera should be started first, then the slave. Make sure the two are running identical code before starting the take. Usually TOD code is used.

If you don’t want the cameras wired together, you may be able to jam-sync one camera with the code from another or from a separate timecode source (such as Ambient’s Lockit box or Denecke’s Syncbox; see Fig. 11-20). The cameras are then used in free run mode and should maintain the same timecode. However, timecode may drift slightly over time, so you may need to rejam the cameras every few hours to keep their timecode identical.

Even with the same timecode, two or more cameras may not be perfectly in sync with each other for editing or live switching. For perfectly matched editing from one to the other, the cameras should be genlocked together. This can be done on professional cameras by running a cable from the video-

out connector on one camera (or from a separate sync source) to the genlock-in connector on the other. With HD cameras, genlock is properly called trilevel sync. There are Lockit boxes and Syncboxes that can generate trilevel sync and timecode, to permit genlocked shooting with cameras not tethered by a wire.

You can think of timecode as an organizational tool for keeping track of your material and locating it later. If you plan to do any editing, timecode is more than that: it’s a crucial part of how the editing system retrieves video and audio data when needed. When using a camera that records to videotape, there are certain ground rules to follow (that are not an issue with file-based cameras).

You never want to have a situation in which the same timecode number occurs on a single tape in more than one place. A common way this can happen is with some DV and HDV cameras that reset the code to 00:00:00:00 every time you remove or insert a tape. You shoot part of a tape, take it out, then put it back in to finish recording it. When you’re later searching for that great shot of a guitar player that starts at timecode 00:12:12:00, you find instead a shot of a drummer with the same code. This can create nightmares in editing.

With most tape camcorders you can avoid this whenever there’s an interruption in code by rewinding the tape into the last previously recorded shot and playing to the end of it (record review or end search on the camera may do this automatically). Then when you start the new recording it will pick up where the timecode ended before (see Operating the Camcorder, p. 125). Some cameras have a regen (regenerate) timecode setting; this will continue the timecode already recorded on tape (as opposed to using “preset,” which will usually start where you have it set). Regen should be used when shooting with a tape that was partially recorded before.

As discussed above, if you shoot carefully in record run mode you can record a whole tape with continuous, ascending timecode. However, wherever there are breaks in the timecode, when you bring the material into the editing system a new clip will be created at the break (see p. 571). When using time-of-day code, timecode breaks happen whenever you stop the camera (because the timecode jumps to a new time when you start recording again). Another way to cause a break is if you aren’t careful and leave a gap after, say, rewinding the tape to check a take.

Timecode breaks aren’t necessarily a big problem, but they can be annoying, especially if you’re shooting a lot of short shots. If you know there’s a break in code, be sure to leave five to ten seconds of preroll time after you start recording before calling “action.” One solution for a tape that has timecode breaks or many short shots is to dub it to a new tape with continuous timecode before editing.

You want to avoid a situation in which a higher number timecode precedes a lower number on the same tape. This can happen when using time-of-day code (see above) or if you preset the code for an hour tape to start at 23:30:00:00 (because it would finish at 00:30:00:00). Editing systems expect the numbers on a tape to be ascending and get confused if a high number comes before a low number.

If you absolutely can’t avoid this happening, make sure you note it carefully on the tape box or in the log for later reference.