PGDEL/DECP05/Unit3/Ch03.11

= DECP 05: Developing e-Content =

Video File Format
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.

videos are packaged up into encapsulation containers, or wrapper formats, that contain all the information needed to present video. Videos have a lot of different information that can be "wrapped" up into these containers - including the video stream, audio stream, metadata, subtitles, chapter-information, synchronization information, etc...  For multimedia data streams to be useful in stored or transmitted form, they must be encapsulated together in a container format.

Video Compression & Codecs

As a general rule, the more bits/second (the amount of data per second that's required to render audio and video content) in a video file, the better the resulting quality. The other part of the equation has to do with how the data is compressed and de-compressed as some compression schemes are better than others. Compressing data essentially relies on algorithms to pull data out with the goal of making big data chunks smaller. Doing this makes for better quality video while taking up less space which is particularly important for delivering video over the web.

A codec - which is a combination of the words "compressor/decompressor" (or coder/decoder) is a set of instructions that identifies the method used to compress data into fewer bytes, as well as doing just the opposite when a video file is played back, decompressing it. So, a video codec, is a compression scheme to compress a video stream while an audio codec would be a compression scheme for audio.

Examples of Compression Schemes:

Video = H.264, H.263, VP6, Sorenson Spark, MPEG-4, MPEG-2,

Audio = AAC, MP3, Vorbis,

Metadata = XML, RDF, XMP,

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