Video Compression

  1. What is Bit-rate?
  2. What is Codec?
  3. What is Compression?
  4. What is M-JPEG?
  5. What is MPEG 4?
  6. What is H.264?
  7. How does H.264 compare to MPEG4 and M-JPEG?

  1. What is Bit-rate?
    The amount of compressed video data delivered into the decoding system. The higher the bit-rate, the higher the quality and/or the resolution of the video. For optical disc formats, this is usually measured in megabits per second (Mbps).

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  2. What is Codec?
    Contraction of Compressor-DeCompressor. This term is often used to refer to the compression scheme used for video processing.

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  3. What is Compression?
    The process of shrinking the size of data so that it uses less storage space and less transmission bandwidth. With video, sacrifices in video quality are almost always “traded off” against the resulting file size.

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  4. What is M-JPEG?
    M-JPEG, or Motion JPEG, is an informal name for multimedia formats where each video frame or interlaced field of a digital video sequence is separately compressed as a JPEG image. Motion JPEG uses intraframe coding technology that is very similar in technology to the I-frame part of video coding standards such as MPEG-1 and MPEG-2, but does not use interframe prediction. The lack of use of interframe prediction results in a loss of compression capability, but eases video editing, since simple edits can be performed at any frame when all frames are I-frames. JPEG has a relatively high bit rate for the delivered quality, requiring more storage space than more modern for a given image quality.

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  5. What is MPEG 4?
    MPEG-4 is a collection of methods defining compression of audio and visual (AV) digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group (MPEG) under the formal standard ISO/IEC 14496. Uses of MPEG-4 include compression of AV data for web (streaming media) and CD distribution, voice (telephone, videophone) and broadcast television applications. Various network providers can use MPEG-4 for data transparency. With the help of standard procedures such data can be interpreted and transformed into various signals compatible with any available network. The MPEG-4 format provides the end users with a wide range of interaction with various animated objects.

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  6. What is H.264?

    H.264 is a new video compression scheme that is becoming the worldwide digital video standard for consumer electronics and personal computers. In particular, H.264 has already been selected as a key compression scheme (codec) for the next generation of optical disc formats, HD-DVD and Blu-ray disc (sometimes referred to as BD or BD-ROM) H.264 has been adopted by the Motion Picture Experts Group (MPEG) to be a key video compression scheme in the MPEG-4 format for digital media exchange. H.264 is sometimes referred to as “MPEG-4 Part 10” (part of the MPEG-4 specification), or as “AVC” (MPEG-4’s Advanced Video Coding).

    This new compression scheme has been developed in response to technical factors and the needs of an evolving market: MPEG-2 and other older video codecs are relatively inefficient. Much greater computational resources are available today. High Definition video is becoming pervasive, and there is a strong need to store and transmit more efficiently the higher quantity of data of HD (about 6 times more than Standard Definition video).



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  7. How does H.264 compare to MPEG4 and M-JPEG?
    H.264/AVC/MPEG-4 Part 10 contains a number of new features that allow it to compress video much more effectively than older standards and to provide more flexibility for application to a wide variety of network environments. Quality and Size (Bit-rate) H.264 clearly has a bright future, mostly because it offers much better compression efficiency than previous compression schemes. The improved efficiency translates into three main benefits, or a combination of them: Higher video quality at a given bit-rate: reduction in artifacts such as blockiness, color bands etc.

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