Ch. 9 Digital Video System

Sequential Couleur Avec Memoire

SECAM. Television Standard used in France, Russia, and many African and Eastern European nations.

Chrominance (C, chroma)

The color component of the video signal. Made up of hue (controls the color and saturation of colors which in turn controls the intensity of colors).

color sampling

a way of eliminating unnecessary data in order to save space.

DV compression

a way of reducing the amount of data flowing from the ADC by discarding visual detail that is either imperceptible to the human viewer or redundant. The programs that perform this are CODECS.

Digital Zoom

an in-camera special effect in which the circuitry in the camera magnifies the captured video signal by selecting the central pixels and blowing them up. lose significant resolution.

drop outs

data loss on the tape

Onboard batteries

dc power provided by these or via an adaptor that transforms unstable ac power to dc.

Helical scanning

diagonal track that give the write heads more recording space on the tape.

Difference in frame rate btw film and NTSC

film runs at a frame rate of 24 fps, the frame rate for NTSC video is slightly less than 30 fps.

manual functions (of camera)

manual functions (of camera)

S-video connector

super video connector. four pin component connector.

Analog (video and audio)

the creation, recording, playback, and distribution of the video/audio signal are accomplished in videotape via electronic waveforms and magnetic particles, which are, respectively, analogous to the original light values of the image and the acoustic waves of the audio.

Imaging Plane (Target)

the face of a CCD chip (charged coupled device)

interlaced scanning

the NTSC standard process of reading one field of video and then integrating a second field. This process happens at a rate of 30 fps (60 fields per second. therefore 60i (for interlaced).

*Resolution

the ability to reproduce visual detail: sharpness of line, subtlety and degrees of luminace, and accuracy of color.

Vertical Resolution

vertical dimension of frame composed of horizontal lines stacked up on top of each other, the more horizontal scan lines a picture has, the better the vertical resolution

write heads

video and audio data is laid down onto the metal oxide surface by these which are mounted on a spinning drum. they increase tape speed without using up more tape.

24p

video signal with a progressive scan frame rate of 24 frames per second. Developed specifically to be compativle with and to duplicate the look of motion picture film.

Media bay

where the video signal is recorded (on camera)

Field of Video

A half-resolution image that the CCD outputs (first outputs odd-numbered horizontal lines.

Bit rates

ADC sampling rates.

Horizontal pixels

ATSC standards clearly articulate the max number of these that can make up each scan line.

CCD chip

Charged coupled device. It's a solid state sensor composed of hundreds of thousands to millions of light-sensitive photodiodes called pixels (picture elements) that are linked together (coupled) and aligned in tight horizontal rows.

Digital Video (and audio)

Create, record, and disseminate video and audio by transforming light values and acoustic energy into binary code, or a series of ones and zeros.

DV25

DV, DVCPRO, DVCAM are referred to as this.

Progressive scanning

Differes from interlaced scanning in that one frames is not made up of two interlaced fields (odds/evens). Instead, it draws full frame of video (all horizontal lines) from top to bottom at a rate of 30 frames per second (some at 60). Better resolution, fits better with LCDs

Summary of NTSC Broadcast Video Standards

Frame rate = 29.97 fps interlaced One frame = two interlaced fields (59.94i) Horizontal lines per field = 262.5 Horizontal lines per frame = 525 Aspect Ration = 4:3

Differences between NTSC, PAL, and SECAM

Frame rate and the number of horizontal lines. PAL/SECAM = 625 horizontal lines. Systems are not compatible with each other.

National Television Standards Committee

NTSC. Made up of 525 horizontal scan lines. Ensure system compatibility in any country that uses it.

Phase Alternating Line

PAL. Television standard used in China and most of the countries in Europe.

Evolution

Technological evolution. NTSC phasing out. ATSC coming in (Advanced Television Systems Committee). Changes in aspect ration, frame rate of video, number of horizontal lines that make up a frame, and scanning process.

Interlaced Scanning

The electronic process NTSC video uses. This is a major difference btw how images are created and then played back in film and with NTSC.

Luminance Signal (Y)

The element of the video image that determines image brightness (shades of black and white).

Target

The tube in which an electron gun at the back of the CRT (cathode ray tube) sprays a stream of electrons with fluctuating electrical voltage against the inseide of the target.

Scan lines

Two series of stacked horizontal rows containing the pixel specific voltage information that the CCD chip outputs. 262.5 scan horizontal scan lines in one field of NTSC.

Component video (Y/C video)

keeps chrominance and luminance components of the signal separate for a superior image.

Lossless compression

kind of compression where no data is lost

White balance

adjusting the CCD's color circuitry to match the color temperature of the light source.

Optical zoom

adjusts the central lenselement to magnify or demagnify the scene being shot. composition and perspective of image change but the resolution of the video remains the same.

Digital Signal Processor (DSP)

after ADC has crunched the numbers, the raw digital video data from each of the CCD chips is sent here to create the final, digital image

Composite Video

all of the elements that make up the video signal, luminance (Y) and chrominance (C) are encoded together and transmitted via a single wire, like RCA or BNC cable.

Servo zoom control

along with the video zoom lens, this allows you to glide through the zoom range, from wide angle to telephoto with the touch of a button. Usually done with a rocker switch.

High Definition Video

applies to ATSC 6 standards for this meaning video formats with vertical resolution (number of horiztonal scans lines) of either 720p, 1080i, or 1080p. aspect ratio 16:9

Audio line signal input and output (I/O)

audio line input: want to record audio from a line signal device (ex cd player)

Decompresses

codec decompresses info by reconstructing the data through duplication of that one numeric calue for the green areas of the frame

Onboard microphones

come with any camcorder (sound)

R = C/O

compression ratiosfor a specific format are expressed as the sive of the compressed data to the original size of the digital information.

Nondrop-frame T.C.

counts frames according to the original B&W video frame rate, assigning a new number to each video frame at a consistent rate of 30 frames per second. It is seldom used. Isn't reflecting real time. Just frames.

lossy compression

discarding imperceptible data and redundant data

External microphone inputs

distinguishes a professional camera from a consumer one.

Active lines

only lines counted when describing a system's vertical lines of resolution

Composite video and audio

output for viewing footage on a regular NTSC monitor or transferring to an analog format like VHS.

Codecs

perform DC compression

Pixels

picture elements. Tiny capacitors. Also voltage sensitive phosphors.

Color depth sampling

reduces data

Compression

reduces data

prism block

the light gathered from the lens first passes through this located just behind the lnes. it splits the image into the three primary colors of light: red, greed, and blue (RGB).

Vertical lines of resolution and horizontal pixels

the number of horizontal lines from top to bottom and the number of pixels that comprise each horizontal line for any given format.

Quantizing

the process of transforming analog information into digital data. ADC has to regularly sample the constantly flowing stream of voltage information (Bit rates)

Drop-frame timecode

the standard and default method for counting and addressing frames with ID numbers with DV cameras and nonlinear editing.

Timecode (T.C.)

the system in video y which every frame is assigned a specific and unique number based on the 24 hour clock- hours:minutes:seconds:frames.

Vertical retrace

the top of the CCD chip. (scanning pattern starts from the top to the bottom filling in the even numbered horizontal rows). Also has 262.5 horizontal lines.

Firewire connector (IEEE 1394)

transfers digital data from the camera to your computer hard drive while capturing footage for editing or you can connect to a third party recording decice for recording directly to hard drive.

Analog to digital converters (ADC)

transforms analog into digital data, meaning binary code (a series of 1s and 0s).