The concept of
analog video compression dates back to 1929, when R.D. Kell in
Britain proposed the concept of transmitting only the portions of the scene that changed from frame-to-frame. The concept of
digital video compression dates back to 1952, when
Bell Labs researchers B.M. Oliver and C.W. Harrison proposed the use of
differential pulse-code modulation (DPCM) in video coding. In 1959, the concept of
inter-frame motion compensation was proposed by
NHK researchers Y. Taki, M. Hatori and S. Tanaka, who proposed predictive inter-frame video coding in the
temporal dimension. In 1967,
University of London researchers A.H. Robinson and C. Cherry proposed
run-length encoding (RLE), a
lossless compression scheme, to reduce the transmission bandwidth of
analog television signals. The earliest digital video coding algorithms were either for
uncompressed video or used
lossless compression; both methods were inefficient and impractical for digital video coding. Digital video was introduced in the 1970s,
Motion-compensated DCT Practical
video compression emerged with the development of
motion-compensated DCT (MC DCT) coding, The other key development was motion-compensated hybrid coding. which combines predictive coding with transform coding. He examined several transform coding techniques, including the DCT,
Hadamard transform,
Fourier transform, slant transform, and
Karhunen-Loeve transform. For the spatial transform coding, they experimented with different transforms, including the DCT and the
fast Fourier transform (FFT), developing inter-frame hybrid coders for them, and found that the DCT is the most efficient due to its reduced complexity, capable of compressing image data down to 0.25-
bit per
pixel for a
videotelephone scene with image quality comparable to a typical intra-frame coder requiring 2-bit per pixel. who developed a fast DCT algorithm with C.H. Smith and S.C. Fralick in 1977, and founded
Compression Labs to commercialize DCT technology.
Video coding standards The first digital video coding standard was
H.120, developed by the
CCITT (now ITU-T) in 1984. H.120 was not usable in practice, as its performance was too poor. In 1999, it was followed by
MPEG-4/
H.263, which was a major leap forward for video compression technology. It was developed in 2003, and uses patents licensed from a number of organizations, primarily Panasonic,
Godo Kaisha IP Bridge and
LG Electronics. H.264 is one of the video encoding standards for
Blu-ray Discs; all Blu-ray Disc players must be able to decode H.264. It is also widely used by streaming internet sources, such as videos from
YouTube,
Netflix,
Vimeo, and the
iTunes Store, web software such as the
Adobe Flash Player and
Microsoft Silverlight, and also various
HDTV broadcasts over terrestrial (
ATSC standards,
ISDB-T,
DVB-T or
DVB-T2), cable (
DVB-C), and satellite (
DVB-S2). A main problem for many video coding formats has been
patents, making it expensive to use or potentially risking a patent lawsuit due to
submarine patents. The motivation behind many recently designed video coding formats, such as
Theora,
VP8, and
VP9 have been to create a (
libre) video coding standard covered only by royalty-free patents. Patent status has also been a major point of contention for the choice of which video formats the mainstream
web browsers will support inside the
HTML video tag. The current-generation video coding format is
HEVC (H.265), introduced in 2013. AVC uses the integer DCT with 4x4 and 8x8 block sizes, and HEVC uses integer DCT and
DST transforms with varied block sizes between 4x4 and 32x32. HEVC is heavily patented, mostly by
Samsung Electronics,
GE,
NTT, and
JVCKenwood. It is challenged by the
AV1 format, intended for free license. , AVC is by far the most commonly used format for the recording, compression, and distribution of video content, used by 91% of video developers, followed by HEVC, which is used by 43% of developers. ==List of video coding standards==