T351 Week 11 - Spring 2008

Agenda

• Review art videos
• Legal Issues
• Codecs / Digitizing / Color Sampling
• Production tips

Readings:

Cybercollege.com units 66 & 67

Announcements / Reality Check

• Wednesday is the cutoff for 400-level production applications and Telecom Scholarships
• MultiVisions Festival next Friday
• Critiques - Don't forget that you need to submit a critique. These are due within a week of your project deadline. So you need critques for your art video, storytelling exercise and final project.
• Storytelling exercises: No lab this week. But you do need to turn in your pre-production materials now- or as early as possible this week. Definitely before you shoot. We will not accept these afterwards (That is why they are pre-production). You will shoot your projects this week. Completed projects due next week by the end of lab. (We'll take a little time to help you edit. like we did with the art videos.)

Production Observations

We had many outstanding Art Videos. (look at some)

Legal Issues

In terms of the law, news & entertainment programming are viewed differently and afforded different restrictions.

For instance in shooting news, if a popular song happens to be playing on someone's radio while giving a soundbite, or if a copyrighted piece of artwork is visible in the background of a shot, chances are very slim that legal action will be taken.

However if one were producing a piece of entertainment and didn't clear the rights to use the music or image, they'd be open to a couple of lawsuits.

As producers, videographers, or editors, it's important to understand the basics of law as it pertains to TV.

Privacy - everyone is entitled to this. However those in the public spotlight are given less protection.

Intrusion - Varying limits on the level you can intrude into a person's privacy.

Access - Generally shooting  on public property is OK. Private property for news is another matter.

Commercial appropriation - It is NOT OK to use someone else's likeness to further your own cause.

Staging - Can't "stage" or reennact events unrealistically for news or documentary purposes. Be careful with using comparable footage as well.

Fair Use - Allows existing intellectual property to be used in teaching, news and other applciations. (Not well defined)

Shield Laws - Protecting sources. States offer differing protection than the Feds.

Defamation (libel & slander) - Presenting content that lowers the public's estimation of a person. Negligence (not bothering to check facts).

Public Domain - Copyright has expired.

Legal contracts:

There are three types of legal contracts you should be familiar with:

• Model Releases
• Location Releases
• License Agreements (Performance, mechanical & synchronization rights)

Model/Talent Releases: These agreements outline the conditions of which the talent will appear in a program.

Location Releases: These agreements outline the conditions of which a certain locations is used in a program.

License Agreements provide for the limited use of someone else's copyrighted material (known as intellectual property). Anything that has been created, written, composed etc is covered and protected by Federal copyright law. Music is usually the easiest thing to procure a clearance for (most TV & radio stations have blanket licenses). Prints, photos, paintings & other visual items are much trickier.

You must be very careful with what you have as a backdrop behind an interview or on a set. Avoid any identifiable artwork or commercial logos.

• Performance rights are necessary to broadcast or perform the work publicly. Broadcasters also need to obtain Performance Rights, since they are publicly transmitting the material. pay BMI & ASCAP in order to broadcast existing music.
• Mechanical rights define the terms a work may be used in an audio-only product, such as CDs.
• Synchronization (Synch)rights are used to define how a work can be used in a soundtrack to a video or film. These are licensed to the producer of the film or program.

E & O Insurance - Errors and Ommissions insurance is a sort of "catch-all" type of insurance that protects you against many unforeseeable issues. All producers should have this.

Video Codecs vs. architecture

A few popular multimedia systems include:

• Quicktime (Apple)
• Windows (Windows)
• Real

Don’t confuse codecs with the video system or architecture. QuickTime is multimedia architecture created by Apple. It supports many different file types and codecs. Similarly, Windows Media (what once was Netshow) is Microsoft’s audio/video architecture. Another popular Internet architecture is Real Systems.

So when you see that a file ends in ".mov" you can bet that QuickTime can support it but you'd have to analyze it to see what the particular codec it is. Most digital video editing systems on the Mac use QuickTime architecture. If you see media ending in .asf, it's supported by Windows Media.

Each architecture supports a variety of different codecs.

What is a codec?

Codec is an acronym that stands for "compressor/decompressor or coder/decoder. A codec is a method for compressing and decompressing digital information. It can use specialized hardware, software or a combination of both.

Here are some popular video codecs:

MJPEG - This is the motion form of JPEG (Joint Photography Experts Group). Many versions of video editing systems use MJPEG (M100, Avid)

Cinepak - Developed by now-defunct Radius. Cinepak, was developed to put small movies on CD-ROMs.

Sorenson – Well supported by a number of platforms.

Indeo – Mainly for the PC platform, Indeo has gone through many versions. For more info visit: http://www.ligos.com/

Smacker – Developed for games. For more info visit: http://www.radgametools.com/ Also home to Blink (another game codec)

RealVideo – Developed by Real, it’s a streaming video codec for use on the web. For more info visit: http://www.real.com/

H.261 & H.263 - Video-conferencing codecs.

MPEG - (Moving Picture Experts Group) uses interframe compression and can store audio, video, and data. The MPEG standard was originally divided into four different types, MPEG-1 through MPEG-4.

MPEG-2 is widely used on commercial DVDs.

DV - uses 5:1 compression Other variants of DV include DVCAM (Sony) and DVCPRO (Panasonic).

To convert video into a digital signal for any of the above mentioned codecs, we need to first digitize it.

Digitizing

Digitizing is the process of converting an analog signal into digital form. We do this to create digital video. Digital video is video that has been digitized and is now represented by binary code- 1s and 0s.

When we digitize video, we have to store the data somewhere- onto tape, disk, or even a memory chip. (Digital still cameras can capture small amounts of video directly onto a chip) When digitizing, compression is often used, in order to fit the most information into the smallest space. specialized file formats or data storage methods, called Codecs are used.

 

 

Visit http://www.adamwilt.com/DV-FAQ-tech.html#colorSampling for a more detailed explanantion of this.

How It Works

A video signal consists of luminance (black and white) and chrominance (color) information. While the luminance and chrominance are combined to create a TV display, the two signals are treated differently. TV works sort of like a coloring book. The luminance draws the outlines (define darks and lights) and then the color is applied.

You can see the luminance portion of the signal on a TV monitor by turning the color (chrominance) all the way down.

Most of the important information is in the luminance portion of the signal.

Sampling (frequency) & Quantizing (bit-depth):

When we digitize video, we sample it. We take a digital snapshot and convert it into 0s and 1s. This is true for audio, video or a combination of the two.

• Sample rate is how many times per second we take a pitcure.
• Quantizing is how good the picture is.

Here are a few different ways audio can be digitized:

• 8 bit at 22KHz (low end, computer alert sounds)
• 16 bit at 44.1 kHz (DAT, CD, MP3 at high quality)
• 16-bit at 48 kHz (DV, DAT/mini disc)
• 24 bit at 48 kHz (High-end DATs & workstations)

The higher (faster) the sampling rate, the better the quality. The larger or deeper the bit depth, the better the quality is.

The digitizing process:

1. Capture the original signal from an anaolog source (tape or live)

2. Sample the input signal. This simulates the analogue signal in the digital domain

3. Quantize the signal. This gives each sample a numeric value.

4. Compress the signal. The overall amount of data is reduced to a more reasonable size.

5. Record the signal. Once digitized, the signal may be recorded on a tape, RAM, optical disk or computer disk.

Color difference signals are one way to break down the information in a video signal. (Other ways include composite video, Y/C or S-Video, and RGB.) The color difference signals can be expressed as R-Y, B-Y or Cr, Cb or sometimes U, V. This color difference signals are used in the digitizing process. What the heck is a color difference signal?

Color difference signals: TV uses an additive color system based on RGB as the primary colors. Mix red, green and blue together and you get white, right? Well if the RGB data were stored as three separate signals (plus sync) it would take a lot of room to store all the information. Fortunately some great technical minds figured out a way pack this information into a smaller box (figuratively speaking) devising a way to convert the RGB information into two new video signals that take up less room, with minimal loss in perceived picture quality. The color difference signals and are typically represented by UV or Cr Cb. So when you see YUV it is referring to Y (luminance) and UV (the two color difference signals).

Combining the RGB signals according to the original NTSC broadcast system standards creates a monochrome luminance signal (Y). So you can basically pull out the blue and red signals and subtract them from the total luminance to get the green info.

4:4:4 vs. 4:2:2 vs. 4:1:1

Today’s digital technology provides us with several ways to digitize video, mainly 4:2:2 and 4:1:1. What do they refer to?

Quite simply, they refer to the ratio of the number of luminance (Y) samples to the samples of each of the two color difference signals.

In the video signal, the most important component is the luminance as it gives us all the detail absolutely necessary in the picture. As a result, we must sample luminance at a very high rate, 13.5 Megahertz (million times per second).

Given that the luminance portion is sampled at 13.5 MHz. Let's apply the beforementioned ratios: 4:2:2 and 4:1:1. In a 4:1:1 component digital sample, the color information is sampled at 1/4 the luminance rate: 3.375MHz. In a 4:2:2 system, the color is sampled at 1/2 the rate of the luminance or 6.75MHz.

What about 4:2:0?

The 4:2:0 is used in MPEG-2 sampling. The two color difference signals are sampled on alternating lines.

What does this mean?

Quite simply, the color depth of a 4:2:2 component digital signal is twice that of a 4:1:1 signal and, from the standpoint of color bandwidth, is twice that of today’s popular component analog formats. This means better color performance, particularly in areas such as special effects, chromakeying, alpha keying (transparencies) and computer generated graphics.

Quantizing / Bit Depth

The next step in the digitizing process is quantizing. In digital video we do not record video as we do in the analogue world, but rather a series of numbers which give us a reference as to what the initial analogue video signal was.

• 8 bit: DV, DVCAM, DVCPRO, Digital S
• 10 bit: Digital Betacam, D1

Production Tips

Here are a few general production tips:

• Establish your location early in the scene. Viewers need to know where we are (who and when too).
• When shooting B-roll or any footage to drop into anything, shoot mini-continuity style. Shoot every action (eg. someone on phone) with a WS, a MS, an OTS, and a CU following the 180-rule. This way you can provide meaningful B-roll which edits nicely.
• When using B-roll use a sequence of 3 or more shots. In other words don't just drop in one shot, but use a sequence of at least 3 shots.
• Always start and end your sequence in black. You can start with a fade up from black and end your sequence with a fade down to black. (Some audio should accompany the video as it does this. Don't cut your audio off at the end - fade it out or backtime it so the song ends.)
• Don't use hand held shots - unless you have a good reason to. The worse thing you can do is hand-held zooms - they look terrible. If you are shooting hand-held keep the lens wide and move closer to your subject, don't zoom.
• TV is a close-up medium. Shoot close-ups! Avoid excessive long and medium shots to tell your story. While they are necessary to establish scenes, embrace medium close-ups and close-ups.
• Lenses: Occasionally check to see if the lens has water drops on it and check your back focus. You often can’t see these through the viewfinder. Never touch the lens with anything other than special lens cleaning paper.

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