MPEG was formed to address the need for standard video and audio formats, and to build on H.261 to get better quality through the use of somewhat more complex encoding methods (e.g., supporting higher precision for motion vectors). Development of the MPEG-1 standard began in May 1988.
The reported completion date of the MPEG-1 standard varies greatly: a largely complete draft standard was produced in September 1990, and from that point on, only minor changes were introduced.
In July 1990, before the first draft of the MPEG-1 standard had even been written, work began on a second standard, MPEG-2, intended to extend MPEG-1 technology to provide full broadcast-quality video (as per CCIR 601) at high bitrates (3–15 Mbit/s) and support for interlaced video.
Filed in 1990 and published in 1993, this patent is now expired. A full MPEG-1 decoder and encoder, with "Layer III audio", could not be implemented royalty free since there were companies that required patent fees for implementations of MPEG-1 Audio Layer III, as discussed in the MP3 article.
It has lower complexity than Layer II to facilitate real-time encoding on the hardware available circa 1990. Layer I saw limited adoption in its time, and most notably was used on Philips' defunct Digital Compact Cassette at a bitrate of 384 kbit/s.
The near-complete draft of the MPEG-1 standard was publicly available as ISO CD 11172 by December 6, 1991.
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 in the process. After 20 meetings of the full group in various cities around the world, and 4½ years of development and testing, the final standard (for parts 1–3) was approved in early November 1992 and published a few months later.
The standard was finished with the 6 November 1992 meeting.
The Berkeley Plateau Multimedia Research Group developed an MPEG-1 decoder in November 1992.
The first three parts (Systems, Video and Audio) of ISO/IEC 11172 were published in August 1993. ==Patents== Due to its age, MPEG-1 is no longer covered by any essential patents and can thus be used without obtaining a licence or paying any fees.
Filed in 1990 and published in 1993, this patent is now expired. A full MPEG-1 decoder and encoder, with "Layer III audio", could not be implemented royalty free since there were companies that required patent fees for implementations of MPEG-1 Audio Layer III, as discussed in the MP3 article.
The even-lower bitrates were introduced because tests showed that MPEG-1 Audio could provide higher quality than any existing (circa 1994) very low bitrate (i.e.
The ISO patent database lists one patent for ISO 11172, US 4,472,747, which expired in 2003.
(Prior to 2006, it was specified by IEEE 1180-1990.) The FDCT process converts the 8×8 block of uncompressed pixel values (brightness or color difference values) into an 8×8 indexed array of frequency coefficient values.
Neither the July 2008 Kuro5hin article "Patent Status of MPEG-1, H.261 and MPEG-2", nor an August 2008 thread on the gstreamer-devel mailing list were able to list a single unexpired MPEG-1 Video and MPEG-1 Audio Layer I/II patent.
A May 2009 discussion on the whatwg mailing list mentioned US 5,214,678 patent as possibly covering MPEG-1 Audio Layer II.
All patents in the world connected to MP3 expired 30 December 2017, which makes this format totally free for use.
All text is taken from Wikipedia. Text is available under the Creative Commons Attribution-ShareAlike License .
Page generated on 2021-08-05