HD Glossary
0.999
NTSC video does not run with a whole number of frames per second. To ensure an easy down conversion to NTSC, HD is often shot in the USA at either 59.94i, 29.97p or 23.976p. Only when the USA switches analogue off completely and NTSC becomes redundant will they be able to revert to whole number frame rates.
1035
The number of lines in the analogue Japanese HD system in the early '90s. Now superseded by the 1080 lines.
1080
HDTV with 1080 lines. Most commonly used system for acquisition and transmission.
16:9
The aspect ratio of high definition video and also of standard definition widescreen video. The picture width and picture height are defined as being 16 units wide and 9 units high.
24P
HD frame rate that is directly compatible with feature film production. It has 24 progressively scanned frames per second.
25P
HD frame rate that use 25 progressively scanned frames per second. It allows an easy down-conversion to standard definition PAL.
2K
Film scanning resolution which is used for the digital intermediate process and special effects shots. Each frame of 35mm original camera negative is digitally scanned to a resolution of 2000 pixels across.
29.97P
HD frame rate that allows an easy down conversation to standard definition NTSC. It runs at 29.97 progressively scanned frames per second, the same rate as NTSC.
30P
HD frame rate that runs at 30 progressively scanned frames per second. It is not yet in common use as down conversation to NTSC is complex. Often people refer to 30P, when in fact they mean 29.97, which is in common use.
4K
Film scanning resolution which is used for special effects shots. Each frame of 35mm original camera negative is digitally scanned to resolution of 4000 pixels across.
4:3
Original aspect ratio of standard definition TV. It is 4 units wide by 3 units high.
4:4:4
Ratio of the sampling frequencies of RGB component video. All components are sampled at the same rate. HDCAM SR is the only tape format that can record this.
50i
An HD frame rate that allows an easy down-conversation to standard definition PAL.
It runs at 50 interlaced fields per second. This rate has the realistic look of video rather than that of film.
59.94i
An HD frame rate that allows an easy down-conversation to standard definition NTSC. It runs at 59.94 interlaced fields per second the same as NTSC.
525
The total number of horizontal TV lines in a standard definition NTSC picture as used in the USA and Japan. Only 483 lines are used for picture information, the rest are reserved for the vertical interval, when the TV scanning spot returns to the top of the frame. The frame is scanned 29.98 times per second.
625
The total number of horizontal TV lines in a standard definition PAL picture as used in the UK and most of Europe (except France). Only 576 lines are used for picture information the rest are reserved for the vertical interval, when the TV scanning spot returns to the top of the frame. The frame is scanned 25 times per second.
60i
An HD frame rate that runs at 60 interlaced fields per second. Often people refer to 60i, when in fact they mean 59.94i, which is the actual field rate of NTSC. It has the realistic look of video rather than that of film.
60P
An HD frame rate that runs at 60 progressively scanned frames per second. It is currently only achievable in the 720 line system due to the excessively large amount of data per second it generates. It has the realistic look of video rather than that of film.
720P
This lower resolution version of HD has 59.94 progressively scanned frames per second. Currently this frame rate is not achievable at 1080 lines due to the vast amount of data it consumes. It offers a better portrayal of motion than interlaced formats and those formats with lower frame rates. 720P also gives better slow motion performance.
480 / 60i
Also called 525i, this is standard Definition SD Format used in today's TV broadcasting supported by almost all video equipment.
Aliasing
A detrimental picture effect where near horizontal lines in the picture appear jagged because there are not enough TV lines to portray them. High definition 25P or 24P pictures do not suffer from this.
Anamorphic
Technique used in film as well as standard definition widescreen video to squash a wider picture than usual onto the same recording medium. In the case of widescreen video, the same number of pixels as in a 4x3 picture are displayed on the screen but they are stretched horizontally to achieve a 16x9 aspect ratio.
Aspect Ratio
The relationship of the picture width to its height expressed as a ratio.
Blu-Ray
Sony's High Definition DVD format, which uses a blue laser to record 25 gigabytes onto a DVD sized disk. The blue laser has a shorter wavelength enabling about 2 hours of compressed HD to be recorded. There are also dual layer versions that hold 50 gigabytes. Playstation 3 will contain a Blu-ray DVD player and this will open up the market for HD games.
CineAlta
Sony's high end acquisition system. Used for 24 frames per second capture. It has a film look to it.
Component
A set of signals, each of which represents a portion of the information needed to generate a full colour video image. The signals are usually distributed separately as RGB or YCbCr. Sometimes a forth signal is added either carrying synchronisation information (S signal) or keying information (K signal). This will provide better signal quality than a composite signal.
Composite
A television signal with both picture and synchronisation information. The signal contains picture, blanking, colour and synchronisation info all combined on to one conductor.
D5-HD
Panasonic HD tape recording format and equipment.
It uses half inch tape based on a D5 cassette. It can record 1080/59.94i, 1035/59i, 1080/23.976p, 720/59.94p, 1080/25p and 1080/50i. It can also replay standard definition D5. It has eight audio tracks. It is often used as a mastering format but is not suitable for acquisition as there is no camcorder available.
Dolby Surround Sound
Widely used system for applying surround sound to recordings, transmission and listening in the home.
Dolby E
Multi channel audio compression system based on AC3 that can encode up to eight channels of audio into a single AES/EBU digital audio channel.
It is typically used to squeeze the six channels of a Dolby 5.1 surround sound mix onto HDCAM, which would otherwise not have sufficient audio channels.
Down-Conversation
The process of reducing High Definition pictures to Standards Definition resolution.
DTS Surround Sound
Alternate system used for acquisition, transmission and listening in the home.
DVCProHD-D7
One of Panasonic's HD formats. It can record 1080i and 720p at 4:2:2 sampling with eight audio channels. It is however heavily compressed and is really only suitable as an acquisition format.
Essence
Essence is the actual digital data that makes up the picture or sound as opposed to Metadata.
Firewire
Serial data interface standard. Used for connecting disk drives to computers but also for the transmission of the various forms of DV video data.
Frame Rate / FPS
Number of frames per second. For progressive (p) systems it can be 24, 25, 30 frames per second. For interlaced (i) systems it can be 50, 60 frames per second.
HDCAM
High definition video tape format and family of equipment developed by Sony.
It records 1920x1080 pixels at a variety of frame rates (23.976P,24P, 25P, 29.97P, 30P, 50i, 59.97i and 60i). It has four audio tracks.
HDCAM SR
New high quality variant of the HDCAM format. It uses mild MPEG4 compression and is capable of recording 4:4:4 or 4:2:2 signals with a minimum of pre-processing. It records 1920x1080 pixels. Its multi generation performance is therefore much better than HDCAM and its ability to capture blue screen is also greatly enhanced. This format can support 12 tracks of audio.
HD DVD
This is Toshibas rival to Sony's Blu-Ray. It uses a blue laser to burn the info but can only store 30GB of data.
HD-SDI
High Definition Serial Digital Interface.
The connections and standard that are used for interconnecting HD equipment. It carries video and audio in real time at 1.485 Gigabits per second over a single coaxial cable and is usually terminated with a BNC plug.
HDV
Internationally agreed format for recording High Definition pictures onto DV tape. HDV is a MPEG-2 transport stream that includes lots of error correction. It captures a 1440x1080 picture than can be expanded to the Common Image Format. It is suitable for use as a second camera being not as good as HDCAM, however it does offer excellent pictures for the money. It also records DVCAM in standard definition widescreen.
HDW730
Sony HDTV 1080 camcorder, switchable between 50i and 60i.
HDW 750P
Sony HDTV 1080 camcorder, switchable between 50i and 25P.
HDWF 900
Sony full spec 1080 camcorder, recording in HDCAM, switchable between 24P, 25P, 30P, 60i and 50i.
HVR Z1E
Sony 1080 professional version of the consumer HDV camcorder. Can record 1080/50i or 720/25P
Interlaced (i)
Scanning system where first the odd lines of a picture are scanned to form one field and then the even lines are scanned to form the next field. This is done to increase the effective refresh rate of the image, since at 25 frames per second the flicker would be noticeable, but with 50 fields per second, it is not.
Letterbox
The process of displaying a picture in its correct aspect ratio by squashing it vertically and filling the remainder of the screen with horizontal black bars.
Metadata
Data about data. Typically Metadata contains information such as shot names and timecode. It does not however contain the actual data that makes up the picture or sound.
MPEG2
Video compression system used in digital television transmission systems and in DVD encoding.
MPEG4
Video compression system starting to be used in digital television transmission systems.
PAL
Phase Alternate Line. Standard definition colour TV system used in UK and most of Europe (except France). It dates from the mid '60s. It is usually but not always (as in Brazil) used with a 625 line picture (575 active picture lines) and with 50 interlaced fields per second.
Pixel
The smallest constituent part of an image. Computer pixels are square as are HD pixels, but standard definition pixels are slightly stretched horizontally. They are even more stretched in an SD widescreen picture.
Progressive
Image scanning system where all the lines of the frame are scanned in order from top to bottom. With progressive pictures at just 25 frames per second, flicker is avoided by the receiver digitally storing the picture and flashing it on the screen at least twice for each frame. The processing of progressive images is easier than that of interlaced images, finer graphics detail can be portrayed by progressive scanning as it does not suffer from the inter-line "twitter" that interlace does. Freeze frames from progressive pictures remain sharp where interlaced pictures either have to be field duplicated, causing aliasing, or interpolated which averages the two fields together and softens them.
RGB
Red, Green and Blue.
The three colour components that make up a TV signal.
Secam
French standard definition video system with 625 lines. Also used in Russia and other former Soviet influenced countries.
SD
Standard Definition.
This refers to video with 525 or 625 lines (483 or 576 active picture lines) encoded in PAL, NTSC or SECAM.
SDI
Serial Digital Interface.
Single wire video connection that transports digital component video in standard definition. It is basic infrastructure of most video facilities and transfers video in real time along with 4 channels of embedded digital audio in a 270 megabit per second data stream
SMPTE
Society of Motion Picture and Television Engineers Based in USA, it sets up committees to define many of the standards and practices used in film and television.
Up-Conversion
The process of converting standard definition images to high definition. This is necessary when archive material has to be included in a programme. The quality is extremely variable. Good widescreen DigiBeta pictures will look reasonably OK, but 4x3 DV material will look dreadful.
Vari-Cam
Panasonic's HD system using 720 lines with variable frame rate. The varicam can work at many different frame rates from 4fps to 60fps and is popular with wildlife cameramen for its ability to over crank and therefore capture good slow motion. A special frame rate converter is used in post production to output 24p, 25p or 29.94p.