Glossary of Video & File terms

 

Definitions of various terms that may be of use.

 

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 a early analogue HD system 'HiVision' developed by NHK, in Japan in the early '90s. Now superseded by the 1080 line standard.

 

1080

HDTV with 1080 lines. Most commonly used system for acquisition and transmission of high definition television.

 

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, as 35mm film movie cameras shoot at 24fps. 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. Not often used as down-conversion to NTSC is complex. Often people refer to 30p, when in fact they mean 29.97, which is in common use, so it's worth checking the frame rate required.

 

4K

Film scanning resolution which is used for special effects shots. Each frame of 35mm original camera negative is digitally scanned to a 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-conversion 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-conversion 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, Canada, Japan and most of South America. 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 29.97 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) and Asia. 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. It offers a better portrayal of motion than interlaced formats, & those formats with lower frame rates. 720P also gives good slow motion performance.

480 / 60i

Also called 525i, this is a standard Definition SD Format used in today's TV broadcasting, supported by almost all NTSC video equipment.

 

Aliasing

A detrimental picture effect where nearby horizontal lines 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 4:3 picture are displayed on the screen but they are stretched horizontally to achieve a 16:9 aspect ratio.

Aspect Ratio

The relationship of the picture's 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. Playstation3 consuls contain a Blu-ray DVD player. Blu-ray became the ‘winner’ in the battle of domestic high definition players, with the format developed by Toshiba, ‘HD-DVD’ being withdrawn from the marketplace in early 2008.

 

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 for the picture information (not the audio) are usually distributed separately as RGB or YCbCr (by three cables, the audio by additional cables) . 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, the audio going by separate cables.

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 to Dolby, 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.

Frame Sequence

When a file/video is changed from (p) progressive to an (i) interlaced format, the frame dominance has to be correct, otherwise the pictures could 'judder' when transferred onto video.

Harding Test

Test devised by Professor Graham Harding to ensure that 'flashing' images in programme material does not induced epileptic fits in viewers.

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

A higher 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. This format uses very expensive machinery and is mainly used in the feature film industry.

HD DVD

This was Toshiba’s high definition rival to Sony's Blu-ray. It uses a blue laser to burn the info but could only store 30GB of data. After several years with both formats in the marketplace, HD DVD was finally ‘abandoned’ in early 2008. The only domestic HD DVD format is now the Sony Blu-ray format.

HD-SDI

High Definition Serial Digital Interface.

The connections and standard that are used for interconnecting HD equipment. A single coaxial cable carries video and audio in real time at 1.485 gigabytes per second, 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 compression system that includes lots of error correction. It captures a 1440x1080 picture than can be expanded to the Common Image Format. It also records DVCAM in standard definition widescreen.

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

Information about data. Metadata typically contains information such as shot names and timecode. It does not however contain the actual data that makes up the picture or sound.

MPEG-2

Video compression system used in digital television transmission systems and DVD encoding. MPEG-2 is the compression system that is used to transmit ‘Freeview’ services and is used to compress pictures onto ‘Standard’ DVDs. It is worth remembering the MPEG-2 compression is not just one type of compression, but covers a whole ‘family’ of compression techniques.

MPEG-4

A more recent, and improved, video compression system for transmission, tape formats, and file making. Again MPEG4 covers a whole ‘family’ compression techniques, and is used is by most High definition formats, as it is an efficient way of compressing picture information. It is currently used by the likes of ‘Sky’ & ‘FreeSat’ to transmitted High definition channels. Again MPEG4 compression is not just 1 type of compression, but covers a whole ‘family’ compression techniques

 

NTSC

National Television System Committee. Standard definition colour TV system used in a number of countries including the USA. It is used with a 525 line picture (480 active picture lines) at 30 frames per second.

 

PAL

Phase Alternate Line. Standard definition colour TV system used in the UK and most of Europe (except France). It was developed in the mid '60s. It is usually, but not always (as in Brazil), used with a 625 line picture (576 active picture lines) and with 50 'interlaced' fields per second.

Pixel

The smallest individual 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 a 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 normally digitally storing the picture and 'flashing' it on the screen at least twice for each frame. 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 "flutter" 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 the basic infrastructure of most video facilities and can transfer 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 various committees to define many of the standards and practices used in the television and film industries.

Super Hi-Vision

Also known as Ultra High Definition, it is an experimental video format being developed by NHK of Japan, BBC and Italy's RAI. It delivers 7680 x 4320 resolution, which is up to 16 times greater than current HDTV standards, and has up to 22 audio chanels.

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 for transmission in high definition. The quality is extremely variable. Good widescreen DigiBeta pictures will look reasonable, but 4:3 DV material will look poor.

HD TAPE FORMATS

There are currently 5 different HD tape formats in mainstream use today and they are:

· HDCAM (Sony)

· HDCAM SR (Sony)

· D-5 HD (Panasonic)

· DVCPro HD (Panasonic)

· HDV (Sony / JVC)

HDCAM

This is the most commonly used HD tape format.

It is based on the Digibeta" tape cassette and includes all 1080 line formats:

 

· 60i

· 59.94i

· 50i

· 30Psf

· 29.97Psf

· 25Psf

· 24Psf

· 23.98Psf

The format uses 4:2:2 sampling, 8-bit quantisation and a compression ratio of 7.7:1.

It provides 4 audio channels, each using 20 bit 48 KHz sampling.

 

 

Cassette Type (Sony)	Cassette Size	Format
		60i 30Psf	59.94i 29.97Psf	50i 25Psf	24Psf 23.98Psf
BCT6HD	Small	6 min.	6 min.	7 min.	7 min.
BCT12HD	Small	12 min.	12 min.	14 min.	15 min.
BCT22HD	Small	22 min.	22 min.	26 min.	27 min.
BCT32HD	Small	32 min.	32 min.	38 min.	40 min.
BCT40HD	Small	40 min.	40 min.	48 min.	50 min.
BCT34HDL	Large	34 min.	34 min.	40 min.	42 min.
BCT64HDL	Large	64 min.	64 min.	76 min.	80 min.
BCT94HDL	Large	94 min.	94 min.	112 min.	117 min.
BCT124HDL	Large	124 min.	124 min.	148 min.	155 min.

 

HDCAM SR

This tape format offers an improved picture quality when compared to the standard HDCAM. Compression is reduced to 2.7:1 (MPEG-4 Studio Profile) and there is a choice of 4:2:2 or 4:4:4 sampling for RGB recording.

 

All 1080 line HD formats are supported as above, and 720 line 59.94p / 50p.

2 Stereo AES/EBU pairs are available for audio recording.

 

HDCAM SR Tape Running Times:

 

Cassette Type (Sony)	Cassette Size	Format
		60i 30Psf	59.94i 29.97Psf	50i 25Psf	24Psf 23.98Psf
BCT6SR	Small	6 min.	6 min.	7 min.	7 min.
BCT133SR	Small	33 min.	33 min.	38 min.	40 min.
BCT40SR	Small	40 min.	40 min.	48 min.	50 min.
BCT64SRL	Large	64 min.	64 min.	76 min.	80 min.
BCT94SRL	Large	94 min.	94 min.	112 min.	117 min.

 

D-5 HD

D-5 HD is based on Panasonic's D-5 standard definition digital cassette format.

The Compression is 4.3:1. Full 4:2:2 bandwidth 10 bit resolution. D-5 HD Supports the same HD formats as HDCAM, with the addition of 720/59.94p. 8 audio tracks - each one 24-bit / 48KHz

Tapes can also be used for Standard Definition. 625/525 recordings.

 

HDD5 Tape Running Times:

Cassette Type (Panasonic)	Cassette Size	Format
		60i 30Psf	59.94i 29.97Psf	50i 25Psf	24Psf 23.98Psf
AJ-D5C23SP	Small	23 min.	23 min.	27 min.	28 min.
AJ-D5C12MP	Medium	12 min.	12 min.	14 min.	15 min.
AJ-D5C33MP	Medium	33 min.	33 min.	39 min.	41 min.
AJ-D5C48MP	Medium	48 min.	48 min.	57 min.	60 min.
AJ-D5C63MP	Medium	63 min.	63 min.	75 min.	78 min.
AJ-D5C94LP	Large	94 min.	94 min.	112 min.	117 min.
AJ-D5C124LP	Large	124 min.	124 min.	149 min.	155 min.

 

 

DVCPro HD

- This is based on Panasonic's DVCPro standard definition digital cassette format.

- Video sampling is 4:2:2, 8 bit quantised. Compression ratio is 6.7:1. HD formats supported :- 1080 line 59.94i/ 50i and 720 line 59.94p. 8 audio tracks (normally 4 analogue inputs) all at 16 bit / 48 KHz.

 

HDV

- Uses tapes which are essentially the same as domestic camcorder MiniDVs.

- Recording format uses MPEG-2 compression (60:1), 8-bit sampling 4:2:0. 25Mbps tape data rate. Audio is stereo - 16-bit / 48kHz.

- Sony camcorders / players support 1080 59.94i / 50i

- JVC camcorders support 720/59.94p

- At 1080i Sony DVM - 63 HD tape runs 63 mins.

- At 720p Sony DVM - 63 HD tape runs 63 mins (Standard Play) or 94 mins (Long Play).

HD Formats

In terms of broadcast television, the following formats are the most relevant:-

The formats below are based on 2 line standards (1080, 720) and 3 scan patterns.

Format	No. of Horizontal Lines	Frame/Field Rate	Vertical Scan Pattern
1080/60i	1080	30 Frames/sec (60 Fields/sec)	Interlace
1080/59.94i	1080	29.97 Frames/sec (59.94 Fields/sec)	Interlace
1080/50i	1080	25 Frames/sec (50 Fields/sec)	Interlace
1080/30Psf	1080	30 Frames/sec	Progressive Segmented Frames
1080/29.97Psf	1080	29.97 Frames/sec	Progressive Segmented Frames
1080/25Psf	1080	25 Frames/sec	Progressive Segmented Frames
1080/24Psf	1080	24 Frames/sec	Progressive Segmented Frames
1080/23.98Psf	1080	23.98 Frames/sec	Progressive Segmented Frames
720/60p	720	60 Frames/sec	“True” Progressive
720/59.94p	720	59.94 Frames/sec	“True” Progressive
720/50p	720	50 Frames/sec	“True” Progressive

Interlaced

This is the long established, conventional TV scan pattern where a frame is composed of 2 interlaced fields; one containing the odd-numbered horizontal picture lines, followed by one containing the even-numbered lines scanned slightly later in time. The second field has the effect of filling in the vertical gaps between lines in the first field.

Progressive

In this case, horizontal picture lines are scanned sequentially from the top to the bottom of the frame.

 

XDCam

Tapeless recording system, using a professional disc similar to Blu-ray, can record in either SD or HD formats.