User:Ryan Cooley/MPEG1: Difference between revisions

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== History ==
== 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. <ref>http://www.chiariglione.org/mpeg/meetings/santa_clara90/santa_clara_press.htm</ref>  
Modeled on the collaborative approach, successes and technology of the [[Joint Photographics Expert Group]], which created the [[JPEG]] still-image compression standard, and [[CCITT]] [[Expert Group on Telephony]], which created the [[H.261]] standard for realtime video transmission on [[ISDN]] lines, the [[MPEG]] working group was established in January 1988 to address the need for standard video and audio encoding formats at data rates of about 1.5Mbps, and exploit the advantages of non-realtime encoding. <ref>http://www.cis.temple.edu/~vasilis/Courses/CIS750/Papers/mpeg_6.pdf pp.2</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.
Development of the MPEG-1 standard began in [[May 1988]].  14 video and 14 audio codec proposals were submitted by individual companies and institutions for evaluation.  The 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 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 approved in early [[November 1992]]. (a draft standard was produced September 1990, and only minor changes were introduced) <ref>http://www.chiariglione.org/mpeg/meetings.htm</ref>  Before the MPEG-1 standard had even been finalized/publihed/drafted 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.


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, 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.
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   Chroma
   Chroma


   I-frames
   I-frames (Intraframe)
   P-frames
    Seeking
   B-frames
   P-frames (Predicted)
   B-frames (Bidirectional)
    Complexity (memory)
    Delay
  "The DC-picture type is used to make fast searches possible on sequential DSMs such as tape recorders with a fast search mechanism. The DC-picture type is never used in conjunction with the other picture types.
 


   GOP
   GOP
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     Coefficients
     Coefficients
     AC  
     AC  
     DC Spatial prediction
     DC (Spatial prediction)
      1/2 or 1/3 interpolation?
     zigzag
     zigzag
   Macroblocks
   Macroblocks
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     Black borders/Noise
     Black borders/Noise
     pel precision (half pixel IIRC)
     pel precision (half pixel IIRC)
     Two MV per macroblock IIRC
     Two MV per macroblock (forward/backward pred)
   RLE
    Prediction error
  Huffman coding
  Huffman Table (for frequent values)
   RLE (fixed length for uncommon codes)
    Variable RLE?
     Others?
     Others?
   CBR/VBR
   CBR/VBR
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   error resilient
   error resilient
   Exceeds MP3 somewhere between 192-256 kbps
   Exceeds MP3 somewhere between 192-256 kbps
  Achieves transparency at 1:6 compression on CD audio.  Quite close to [[Perceptual Entropy]] limit of just over 1:8. <ref>J. Johnston, ''Estimation of Perceptual Entropy Using Noise Masking Criteria,'' in Proc. ICASSP-88, pp. 2524-2527, May 1988.</ref>
<ref>6. J. Johnston, ''Transform Coding of Audio Signals Using Perceptual Noise Criteria,'' IEEE J. Sel. Areas in Comm., pp. 314-323, Feb. 1988.</ref>
    
    



Revision as of 09:41, 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

Modeled on the collaborative approach, successes and technology of the Joint Photographics Expert Group, which created the JPEG still-image compression standard, and CCITT Expert Group on Telephony, which created the H.261 standard for realtime video transmission on ISDN lines, the MPEG working group was established in January 1988 to address the need for standard video and audio encoding formats at data rates of about 1.5Mbps, and exploit the advantages of non-realtime encoding. [1]

Development of the MPEG-1 standard began in May 1988. 14 video and 14 audio codec proposals were submitted by individual companies and institutions for evaluation. The 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. [2]

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 approved in early November 1992. (a draft standard was produced September 1990, and only minor changes were introduced) [3] Before the MPEG-1 standard had even been finalized/publihed/drafted 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. [4] 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 (Intraframe) 
   Seeking
 P-frames (Predicted)
 B-frames (Bidirectional)
   Complexity (memory)
   Delay
 "The DC-picture type is used to make fast searches possible on sequential DSMs such as tape recorders with a fast search mechanism. The DC-picture type is never used in conjunction with the other picture types.


 GOP
   Keyframe placement
 DCT
 Quantization
   Quantizer Noise
   Banding
   Ringing? (large coefficients in high frequency sub-bands)
   Coefficients
   AC 
   DC (Spatial prediction)
     1/2 or 1/3 interpolation?
   zigzag
 Macroblocks
   16 dimentions
   Blockiness
 Motion Vectors/Estimation
   Black borders/Noise
   pel precision (half pixel IIRC)
   Two MV per macroblock (forward/backward pred)
   Prediction error
 Huffman Table (for frequent values)
 RLE (fixed length for uncommon codes)
   Variable RLE?
   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
 Achieves transparency at 1:6 compression on CD audio.  Quite close to Perceptual Entropy limit of just over 1:8. [5]

[6]


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." [7]

 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.cis.temple.edu/~vasilis/Courses/CIS750/Papers/mpeg_6.pdf pp.2
  2. http://www.chiariglione.org/mpeg/meetings/santa_clara90/santa_clara_press.htm
  3. http://www.chiariglione.org/mpeg/meetings.htm
  4. http://www.chiariglione.org/mpeg/meetings/london/london_press.htm
  5. J. Johnston, Estimation of Perceptual Entropy Using Noise Masking Criteria, in Proc. ICASSP-88, pp. 2524-2527, May 1988.
  6. 6. J. Johnston, Transform Coding of Audio Signals Using Perceptual Noise Criteria, IEEE J. Sel. Areas in Comm., pp. 314-323, Feb. 1988.
  7. http://www.chiariglione.org/mpeg/faq/mp1-sys/mp1-sys.htm

External Links