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]]. | 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 | 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. | ||
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 | 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 | Two MV per macroblock IIRC | ||
RLE | RLE | ||
Huffman coding | Huffman coding | ||
Others? | Others? | ||
CBR/VBR | |||
Spacial Complexity | Spacial Complexity | ||
Temporal Complexity | Temporal Complexity | ||
== Audio == | == Audio == | ||
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Part 3 of the MPEG-1 standard covers 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 | Musicam | ||
Audiophile | 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 === | === Layer III/MP3 === | ||
ASPEC | 9 months? | ||
ASPEC (Fraunhoffer) | |||
freq transform encoder | |||
entropy coding | |||
Hybrid MDCT | 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 == | == Systems == | ||
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== See Also == | == See Also == | ||
[[MPEG]] | *[[MPEG]] The Moving Picture Experts Group | ||
[[MP3]] | *[[MP3]] The Cultural Phenomenon in Music | ||
== References == | == References == | ||
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== 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
References
External Links
- http://www.chiariglione.org/mpeg/ Official Home Page of the Moving Picture Experts Group (MPEG) a working group of ISO/IEC