By Josh Emrick

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Video Codecs

• By Josh Emrick

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What is a Codec?

• A video codec is a device or software module that
  enables video compression or decompression for
  digital video.

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Why are codecs important?

• Today, digital video codecs are found in DVDs and
  on the Internet. Online video material is encoded
  in a variety of codecs, and this has led to the
  availability of codec packs
• Codec packs are pre-assembled set of commonly
  used codecs combined with an installer available
  as a software package for computers.

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Terms to know for video codecs

• Video compression refers to reducing the quantity
  of data used to represent video content without
  excessively reducing the quality of the picture.
• Bitrate or datarate is the number of bits used
  per unit of time to represent a continuous medium
  such as audio or video after compression. Bitrate
  (bps) is the standard unit of measurement for
  data compression.

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Types of compression

• Temporal Compression- compression by removing
  redundant frames.
• Spatial Compression-compression by removing
  redundant pixels in a frame.

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Common video formats

• AVI-Audio Video Interleave is a multimedia
  container format made by Microsoft in November
  1992 as part of the Video for Windows technology.
  AVI files contain both audio and video data in a
  standard container that allows simultaneous
  playback.

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Common video formats

• Divx, xvid, and 3ivx- popular codecs that are
  commonly used today. These codecs use spartial
  compression.

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Common video codecs

• H.263(also known as MPEG4 and AVC)- developed by
  the ITU-T, was the first practical digital video
  compression standard. This format uses a type of
  Temporal compression.

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Common video codecs

• WMV(Windows Media Video) Microsoft's video codec
  designs including WMV 7, WMV 8, and WMV 9. WMV
  can do high resolution video, but it is known for
  having high lossy compression due to using
  spartial compression.

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Common video codecs

• .rmvb (Real Media Variable Bitrate)- A
  increasingly popular format used for video today.
  Its increasing popularity is due to its
  surprisingly good compression ratio. It achieves
  this by varying the bitrate of the video
  according to the amount of action. The less
  action there is the smaller the bitrate at that
  point.This is a type of temporal compression.

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Common video formats

• MKV(Matroska) is a project to develop an open
  multimedia container format similar to MPEG's
  MP4. MKV is a unique format because it allows
  multiple streams of audio and video to be encoded
  together. Each stream is also encoded in another
  format such as MPEG4 or avi.

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More video codecs

• VOB (DVD-Video Object) a container format
  contained in a DVD. VOB files are very similar to
  MPEG-2 files and can even have their extensions
  changed to mpeg2 and still play.

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Example Divx
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Example WMV
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Example VOB
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Example Avi
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Bibliography

• www.wikipedia.com
• Computer Science Illuminated, Nell Dale John
  Lewis,Jones and Bartlett publishers, Sudbury
  Massachusetts.
• Clips taken from Underworld Revolution