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mpeg(4)								       mpeg(4)

NAME    [Toc]    [Back]

     mpeg - MPEG compression format

DESCRIPTION    [Toc]    [Back]

     MPEG is a set of standards	for digitally coding audio and video.  The
     name is derived from Moving Pictures Experts Group, which is the
     technical committee of ISO/IEC (the International Organisation for
     Standardisation and the International Electrotechnical Commission)
     responsible for developing	these specifications.

     Several standards have been developed, targeted for different
     applications.  MPEG-1 encodes non-interlaced material and is optimized
     for single-speed CD-ROM bitrates (about 1.5 Mbps).	 MPEG-2	handles
     interlacing and is	intended for applications at higher bitrates (4	Mbps
     or	greater) like studio-quality TV.  MPEG-4 is in its early stages	and is
     targeted for very low bitrates that may be	useful for videophone and
     other applications. (MPEG-3 was intended for HDTV/ATV but was merged with

     Below we describe the components of MPEG-1	(unless	otherwise indicated,
     subsequent	references to MPEG in this document apply to MPEG-1 only).
     This standard specifies the syntax	for three types	of bitstreams :
     video, audio, and systems.

   Video Bitstream    [Toc]    [Back]
     Compression utilizes tranform coding and motion estimation, which attempt
     to	remove spatial and temporal redundancies in the	original image
     sequence.	Image dimensions up to 4096 by 4096 pixels and various frame
     rates up to 60 Hz are specified (field information	is not defined in the
     video bitstream), with bitrates up	to 105 Mbps allowed.

   Audio Bitstream    [Toc]    [Back]
     Compression is based on subband coding, which divides the input into
     different frequency bands and allocates bits across frequencies based on
     perceptual	importance.  Mono and stereo sources are supported at sampling
     rates of 32, 44.1 and 48 KHz, and allowable bitrates range	from 32	to 448

     Three layers of encoding are specified : Layers I,	II, and	III.
     Generally speaking, the higher layers provide better compression (lower
     bitrates for the same audio quality) at the expense of greater
     computational complexity.	The higher layers are also supersets of	the
     lower layers in the sense that a Layer III	decoder	must be	able to	decode
     an	audio bitstream	of any layer, and a Layer II decoder must be able to
     decode bitstreams from Layers I and II.

									Page 1

mpeg(4)								       mpeg(4)

   Systems Bitstream    [Toc]    [Back]
     The systems specification defines how the compressed audio	and compressed
     video bitstream are multiplexed; no additional compression	is performed.
     This layer	serves to packetize and	interleave the compressed audio	and
     video data, along with timestamp information and decoder buffering
     requirements.  Up to 16 video and 32 audio	streams	may be multiplexed in
     a single systems stream.

PRODUCTS    [Toc]    [Back]

     The MPEG compression format is supported by several developer and enduser
 products.  Current support is	limited	to MPEG-1, Layers I/II audio,
     and systems streams with one audio	track and one video track.

     Compression Library    [Toc]    [Back]
	 Provides MPEG-1 video and audio encoding and decoding.	 See
	 CLintro(3dm), cl_mpeg1(3dm), and cl_aware(3dm).

     Audio File	Library
	 Provides MPEG-1 audio encoding	and decoding.  See AFintro(3dm)
	 and AFaware(3dm).

     Movie Library    [Toc]    [Back]
	 Provides reading and playback of MPEG-1 systems or video
	 bitstreams.  See mvIntro(3dm).

     Digital Media Tools    [Toc]    [Back]
	 Several tools enable end-users	to create, manipulate, and play
	 MPEG-1	bitstreams.  Please refer to the man pages listed in the
	 final section.

FILES    [Toc]    [Back]

	  - sample MPEG-1 systems bitstream file (movie	including

SEE ALSO    [Toc]    [Back]

     The offical MPEG-1	specification :
     ISO/IEC International Standard 11172.  Coding of Moving Pictures and
     Associated	Audio for Digital Storage Media	Up to About 1.5	Mbit/s.

     mediaconvert(1), dmconvert(1), mediaplayer(1), mediamaker(1), CLintro(3),
     cl_mpeg1(3), cl_aware(3dm), AFintro(3dm), AFaware(3dm), mvIntro(3mv),

									PPPPaaaaggggeeee 2222
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