VIDEO FAQ & GLOSSAR

FAQ

What exactly is footage?

In film and video production, “footage” refers to pre-existing (and traditionally often unedited) film content that can be inserted into new productions.

What’s the origin of the term “footage”?

Film has traditionally been measured by length. One foot of 35 mm film represents roughly 1 second. So footage basically describes short pieces of film.

What resolution is High Definition?

There are various High Definition resolutions. The resolutions 1280 x 720px and 1920 x 1080px meet the usual standard. The resolution 1920 x 1080px is called full HD.

Why are SD down-convert sizes different from SD standard sizes?

When we down-convert an HD video with the aspect ratio 16:9 to an SD video with the aspect ration 4:3 we do not cut or “letterbox” the video in order to keep the full SD height (576px bzw. 486px). That’s why we end up with a width of 1024px, or 864px respectively.

Why do we have two different web definitions with different bitrates?

Web Definition I, with a bit rate of 1Mbit/s, is prepared for streaming on the internet without further editing. Web Definition II, which has a higher bit rate of 2.5Mbit/s, is intended for inclusion in web projects.

What is the connection between bitrate, quality and file size?

The higher the bit rate, the larger the file. And the better the quality.

What is streaming?

Data transmission of video on the internet with the special feature that the video can start playing while the transmission is still running. It’s not necessary to wait until the transmission has been completed.

Why do we have different frame rates (image frequency)?

The human eye processes an image series as a sequence at approx. 18 images or more per second. By altering the frame rate between recording and replay it’s possible to generate effects like slow motion or fast motion. Technical requirements for standard definition TV transmission in different parts of the world also necessitate differences in frame rates.

Why can’t my computer replay the video?

Either the appropriate player or this particular codec has not been installed. You can download VLC Mediaplayer which is an universal player able to display the most common codecs.

Glossary

Bitrate	Specifies how much data is processed in a specified time. The information is usually given in Mbit/s (Megabit per second)
Codec	Codec means a procedure and/or programme for digital coding and decoding of data and signals. Examples of codecs: H.264, DNxHD
Realtime	Means that the video signal is replayed at normal speed.
Fps	Abbreviation for “frames per second”. This information specifies how many images are shown per second.
H.264	Codec for highly qualified video compression; also called MPEG4/AVC.
HD	Abbreviation for “high definition”. Higher video resolution than PAL and NTSC, i.e. 1280 x 720px or 1920 x 1080px.
Letterbox	Procedure to display a widescreen format with aspect ratio 16:9 on a regular screen with aspect ratio 4:3. The full width is retained and a black background is inserted in the upper and lower sections of the screen (as when cinema movies are shown on a regular TV screen).
NTSC	Abbreviation for “National Television Standards Committee”. TV standard in USA and Canada, processing 30 full images or 60 half images with a resolution of 720 x 486px.
PAL	Abbreviation for “Phase Alternating Line”. European TV standard which processes 25 full images or 50 half images at a resolution of 720 x 576px.
Quicktime	Platform-spanning file format which can replay video files on the internet due to it’s compression and streaming features.
SD	Abbreviation for “standard definition”. Standard video resolution of PAL and NTSC.
Aspect Ratio	The relationship between width and height in videos. SD with aspect ratio 4:3 produces a nearly square format. HD with aspect ratio 16:9 produces a much wider format.
Slow Motion	Also called “Slomo”. This means that a video signal is replayed more slowly than it was recorded.
Fast Motion	The opposite of slow motion: video signal is replayed faster than it was recorded, so that, for example, a cake baking in the oven for several hours can be shown in a few seconds.