User:Ryan Cooley/MPEG1: Difference between revisions

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== History ==
== History ==


The [[MPEG]] working group began development of MPEG-1 in [[May 1988]].  15 video and 14 audio codecs proposed by members.  The proposed codecs were extensively tested for objective (mathematical) and subjective (human perception) quality.  The winning codecs, based on testing and computational complexity, were refined further  
The [[MPEG]] working group was established in January 1988 and began development of MPEG-1 in [[May 1988]].  14 video and 14 audio codecs were submitted for evaluation by members.  The proposed codecs were extensively tested for computational complexity and subjective (human perception) quality, at (combined video+audio) bitrates of 1.5Mbps.  The codecs that excelled in this testing were utilized as the basis for the standard and refined further, with additional features and other improvements being incorporated. <ref>http://www.chiariglione.org/mpeg/meetings/santa_clara90/santa_clara_press.htm</ref>


After 20 official meetings in various cities around the world, and 4 and a half years of development and testing, the standard was finalized and approved in early [[November 1992]]. <ref>http://www.chiariglione.org/mpeg/meetings.htm</ref>   
After 20 meetings of the full group in various cities around the world, and 4 <sup>1</sup>/<sub>2</sub> years of development and testing, the final standard was (?finalized in 1991 and?) approved in early [[November 1992]]. <ref>http://www.chiariglione.org/mpeg/meetings.htm</ref>  Immediately afterwards, work began on an MPEG-2 standard, intended to extend MPEG-1 technology to provide higher quality video at high bitrates (3 - 15 [[Mbps]]), and support for [[interlaced]] video. <ref>http://www.chiariglione.org/mpeg/meetings/london/london_press.htm</ref>  Due in part to the similarity between the two codecs, all standard MPEG-2 decoders include full support for playing MPEG-1 video.


Immediately afterwards, work began on MPEG-2 to extend MPEG-1 to address the need for higher quality video at high bitrates (3Mbps and up), and support for [[interlacing]].  Due to this similarity, all MPEG-2 decoders also support MPEG-1.
Today, MPEG-1 is by far the most widely compatible lossy audio/video format in the world.  Due to its age, most patents on MPEG-1 Video and Layer II audio technology have expired (MP3 being a notable exception), and can be implemented without payment of license fees in almost all countries.  Most computer software for video playback includes MPEG-1 decoding, in addition to any other supported formats.  The immense popularity of MP3 audio has established a massive [[installed base]] of hardware that can playback all 3 layers of MPEG-1 audio.  The widespread popularity of MPEG-2 (mostly with broadcasters) means MPEG-1 is playable by most digital cable/satellite set-top-boxes, and digital disc and tape players.


Today, MPEG-1 is by far the most widely compatible lossy audio/video format in the world.  Due to its age, it can be implemented without payment of license fees.  Most video players for computers include it along with their other formats.  The immense popularity of MP3 audio means all 3 levels of MPEG-1 audio are playable on a very wide variety of audio hardware.  The widespread popularity of MPEG-2 means MPEG-1 video is playable on most digital cable/satellite set-top-boxes, consumer digital disc and tape players.
Notably, the MPEG-1 standard very strictly defines the [[bitstream]], and decoder function, but does not define how MPEG-1 encoding is to be performed (although they did provide a reference implementation).  This means that MPEG-1 coding efficiency can drastically vary depending on the encoder used, and generally means that newer encoders perform significantly better than their predecessors.


   Began development in 1988  
   Began development in 1988  
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   DAB
   DAB
   MP3
   MP3
   MPEG-2
   MPEG-2?
   DVD players
  audio:
  SVCD
   DVD players (not surround)
  ATSC/HDTV (failed)


== Video ==
== Video ==
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     Black borders/Noise
     Black borders/Noise
     pel precision (half pixel IIRC)
     pel precision (half pixel IIRC)
     Two per block IIRC
     Two MV per macroblock IIRC
 
   RLE
   RLE
   Huffman coding
   Huffman coding
     Others?
     Others?
 
  CBR/VBR
   Spacial Complexity
   Spacial Complexity
   Temporal Complexity
   Temporal Complexity


  CBR/VBR
 


== Audio ==
== Audio ==
Line 91: Line 93:
Part 3 of the MPEG-1 standard covers audio.   
Part 3 of the MPEG-1 standard covers audio.   


=== Layers I & II ===  
MPEG-1 audio utilizes perceptual masking, and sub-band coding to reduce the bitrate of the audio stream.
 
  mono, stereo, joint stereo (impulse, m/s), dual.
 
=== Layer I ===
 
  file extension .mp1
  Simple
  32 sub-bands
  Realtime
  Delay
  Digital Compact Cassette
  Obsolete today
  Time-domain coding/concealment
 
=== Layer II ===
 
  dominant standard
  audio broadcasting
   Musicam
   Musicam
   Audiophile
   Audiophile
   Delay
   impulses
  superior to AC-3
  pro-transparent at 256kbps
  32 sub-bands
  joint stereo (intensity)
  same fundamental problem today
  Focus on [time-domain] critical audio
  error resilient
  Exceeds MP3 somewhere between 192-256 kbps
 


=== Layer III/MP3 ===
=== Layer III/MP3 ===


   ASPEC
  9 months?
   ASPEC (Fraunhoffer)
  freq transform encoder
  entropy coding
   Hybrid MDCT
   Hybrid MDCT
   Aliasing
    pre-echo worse
    aliasing issues
   "aliasing compensation"
  mid/side (or impulse) joint stereo
  576 frequency components
  selectivity
  "If there is a transient, 192 samples are taken instead of 576 to limit the temporal spread of quantization noise"?
  psychoacoustic model and frame format from MP1/2
  ringing
  CBR/VBR
  Frames are not independent


== Systems ==
== Systems ==
Line 120: Line 161:
== See Also ==
== See Also ==


[[MPEG]]
*[[MPEG]] The Moving Picture Experts Group
[[MP3]]
*[[MP3]] The Cultural Phenomenon in Music


== References ==
== References ==
Line 127: Line 168:


== External Links ==
== External Links ==
http://www.chiariglione.org/mpeg/ Official Home Page of the Moving Picture Experts Group (MPEG) a working group of ISO/IEC
*http://www.chiariglione.org/mpeg/ Official Home Page of the Moving Picture Experts Group (MPEG) a working group of ISO/IEC

Revision as of 04:28, 18 March 2008

MPEG-1 articles (MPEG-1, MP1, MP2, MP3) on wikipedia are complete crap. Disorganized, slanted, incomplete, misconstrued, etc. It's far easier to start from scratch than try to fix all the individual existing ones, and will give far better end results; I will copy some content from the existing articles.

Do not make any changes to this page for now. This is my mind-dump and accommodating others before I'm done will just make much, much more work for me. Put any suggestions on the Talk page, and I will eventually address them.

-RC


MPEG-1 was an early standard for lossy compression of video and audio. It was designed to compress raw video and CD audio by a factor of 1:6 without discernible quality loss, making Video CDs and Digital Video Broadcasting possible.

Perhaps the most well-known part of the MPEG-1 standard today is the MP3 audio format it introduced.

The MPEG-1 standard is published as ISO/IEC 11172.

History

The MPEG working group was established in January 1988 and began development of MPEG-1 in May 1988. 14 video and 14 audio codecs were submitted for evaluation by members. The proposed codecs were extensively tested for computational complexity and subjective (human perception) quality, at (combined video+audio) bitrates of 1.5Mbps. The codecs that excelled in this testing were utilized as the basis for the standard and refined further, with additional features and other improvements being incorporated. [1]

After 20 meetings of the full group in various cities around the world, and 4 1/2 years of development and testing, the final standard was (?finalized in 1991 and?) approved in early November 1992. [2] Immediately afterwards, work began on an MPEG-2 standard, intended to extend MPEG-1 technology to provide higher quality video at high bitrates (3 - 15 Mbps), and support for interlaced video. [3] Due in part to the similarity between the two codecs, all standard MPEG-2 decoders include full support for playing MPEG-1 video.

Today, MPEG-1 is by far the most widely compatible lossy audio/video format in the world. Due to its age, most patents on MPEG-1 Video and Layer II audio technology have expired (MP3 being a notable exception), and can be implemented without payment of license fees in almost all countries. Most computer software for video playback includes MPEG-1 decoding, in addition to any other supported formats. The immense popularity of MP3 audio has established a massive installed base of hardware that can playback all 3 layers of MPEG-1 audio. The widespread popularity of MPEG-2 (mostly with broadcasters) means MPEG-1 is playable by most digital cable/satellite set-top-boxes, and digital disc and tape players.

Notably, the MPEG-1 standard very strictly defines the bitstream, and decoder function, but does not define how MPEG-1 encoding is to be performed (although they did provide a reference implementation). This means that MPEG-1 coding efficiency can drastically vary depending on the encoder used, and generally means that newer encoders perform significantly better than their predecessors. 

 Began development in 1988 
 Approved November 1992
 Published August 1993
 Lossy
 most compatible format
 MPEG-2

Application

 VCD players
 DVB
 DAB
 MP3
 MPEG-2?
 audio:
 SVCD
 DVD players (not surround)
 ATSC/HDTV (failed)

Video

Part 2 of the MPEG-1 standard covers video. 


 Part 2
 Dimentions 4094x4094
 Datarate
 Constrained Parameters Bitstream

 Luma
 Chroma

 I-frames
 P-frames
 B-frames

 GOP
   Keyframe placement

 DCT
 Quantization
   Quantizer Noise
   Banding
   Ringing? (large coefficients in high frequency sub-bands)
   Coefficients
   AC 
   DC Spatial prediction
   zigzag
 Macroblocks
   16 dimentions
   Blockiness
 Motion Vectors/Estimation
   Black borders/Noise
   pel precision (half pixel IIRC)
   Two MV per macroblock IIRC
 RLE
 Huffman coding
   Others?
 CBR/VBR
 Spacial Complexity
 Temporal Complexity


Audio

Part 3 of the MPEG-1 standard covers audio.

MPEG-1 audio utilizes perceptual masking, and sub-band coding to reduce the bitrate of the audio stream. 

 mono, stereo, joint stereo (impulse, m/s), dual.

Layer I

 file extension .mp1
 Simple
 32 sub-bands
 Realtime
 Delay
 Digital Compact Cassette
 Obsolete today
  Time-domain coding/concealment

Layer II

 dominant standard 
 audio broadcasting
 Musicam
 Audiophile
 impulses
 superior to AC-3
 pro-transparent at 256kbps
 32 sub-bands
 joint stereo (intensity)
 same fundamental problem today
 Focus on [time-domain] critical audio
 error resilient
 Exceeds MP3 somewhere between 192-256 kbps

Layer III/MP3

 9 months?
 ASPEC (Fraunhoffer) 
 freq transform encoder 
 entropy coding
 Hybrid MDCT
   pre-echo worse
   aliasing issues
 "aliasing compensation"
 mid/side (or impulse) joint stereo 
 576 frequency components
 selectivity
 "If there is a transient, 192 samples are taken instead of 576 to limit the temporal spread of quantization noise"?
 psychoacoustic model and frame format from MP1/2
 ringing
 CBR/VBR
 Frames are not independent

Systems

Part 1 of the MPEG-1 standard covers systems which is the logical layout of the encoded audio, video, and other bitstream data.

"The MPEG-1 Systems design is essentially identical to the MPEG-2 Program Stream structure." [4] 

 Program Stream
 Interleaving
 PES
   Wrap-around
 DTS
 Timebase correction
 Pixel/Display Aspect Ratio


See Also

  • MPEG The Moving Picture Experts Group
  • MP3 The Cultural Phenomenon in Music

References

  1. ↑ http://www.chiariglione.org/mpeg/meetings/santa_clara90/santa_clara_press.htm
  2. ↑ http://www.chiariglione.org/mpeg/meetings.htm
  3. ↑ http://www.chiariglione.org/mpeg/meetings/london/london_press.htm
  4. ↑ http://www.chiariglione.org/mpeg/faq/mp1-sys/mp1-sys.htm

External Links

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