Digital Terminology

Podcasts
A podcast is a media file (usually audio but sometimes video) made available for download to personal computer or a portable device such as an Ipod and can be subscription based.

Web Conferencing
Web conferencing is used to conduct live meetings, training, or presentations via the Internet. In a web conference, each participant sits at his or her own computer and is connected to other participants via the internet.

Webinar/Webcast
A webinar or webcast is an online seminar transmission of an audio and visual media and is usually scheduled for a particular time, but can be on demand over the Internet. The content comes from a single source to multiple viewers simultaneously and when live, webcasts are often interactive allowing viewers to type in questions for the presenter to respond.

Interlacing
This is a technique for processing video that has been used for decades in analog television broadcasts. Each frame of an interlaced video signal shows every other horizontal line of the image, so each frame only uses half the bandwidth than it would sending the entire picture. As the frames are displayed the video signal alternates between showing odd and even lines. When this is done fast enough, the video image looks smooth to the human eye. The downside of interlaced video is that fast motion may appear slightly blurred, so progressive scan signals are often used, which draw each line of the image consecutively.

Progressive Scan
This is the technique used to process video one entire frame at a time.  Used by computer monitors it is often prefered over interlacing for high-end video production. 

Letterbox
This is a term used to display a widescreen (16:9) video image on a standard CRT (4:3) television. The wide screen image will fill the width of the screen and add black bars top and bottom. See Aspect Ratio for an example.

Rendering
This is the process of generating a video production in to its final form before exporting. This include visual transitions, special effects and superimposed video tracks.

CODEC
This the name given to the video or audio compression component that can both compress and decompress files. See Video Formats for more details.

Transcoding
To convert from one compression format to another (eg. from HDV video to MPEG-2 for DVD). Preferably done only once to desired format to avoid loss of quality during compression steps.

Alpha channel (keying)
Extra information stored within an image or video, to definetransparent areas used for keying and superimpositions. Often refered to as an alpha mask. With video this transparent channel is usually created using green or blue screen backgrounds. See Green screening for more information.