The H.265/HEVC or MPEG-5 encoding standard (finalized in
2013) is the next generation of encoding technology after the H.264/AVC or
MPEG-4 standard (finalized in 2003). Just as AVC stands for Advanced Video
Coding, HEVC is an acronym for High Efficiency Video Coding. The 5th
generation number associated with the H.265 and MPEG-5 labels is somewhat
misleading since, in fact, HEVC is only the third generation of MPEG digital
compression technology developed for broadcast television. The initial MPEG-1 standard
(finalized in 1991) was targeted to low-resolution video CD formats, while work
on an MPEG-3 standard, intended to support HD TV formats, was abandoned after a
year or so in favor of a relatively minor extension to the original broadcast
TV standard, MPEG-2 (finalized in 1994).
Compared to other areas of high technology—e.g.,
semiconductors, where “Moore’s Law” predicts capabilities will double every 2
years—the decade-per-standard rate of advance for digital compression is surprisingly
sedate. This relatively slow pace results from two major factors. One factor is
a law of diminishing returns that governs all forms of compression: namely, every
unit of reduction achieved makes it harder to achieve the next unit until, when
some theoretical minimum is reached, infinite force must be applied to make any
further gains.
The second factor is the fact that, practically speaking,
adoption of a new, more efficient broadcast compression technology is tied to
the adoption of a new, higher resolution broadcast standard. For example, the original
MPEG-2 broadcast standard was designed to adequately support the transmission
of SD video formats over available transmission pathways. Although
next-generation H.264/AVC (MPEG-4) encoders were able to cut MPEG-2 bitrates in
half with no loss of video quality, their appeal was nonetheless limited when
they started to appear following completion of the 2003 standard. Older MPEG-2
encoders were still adequate for SD, and both more mature and less costly than
the latest high-powered H.264/AVC encoders.
As a consequence, widespread adoption of H.264/AVC encoders
had to wait on the spread of HDTV programming, which literally overwhelmed
MPEG-2 technology by multiplying SD picture data by a factor of 6X. HDTV
programming, in turn, naturally lagged behind the adoption of HDTV sets. Since
HDTV sets did not reach critical mass in the USA until 2006 (when they finally passed
10% of the installed base and sales figures started climbing rapidly),
broadcasters did not begin buying H.264 encoders in any significant numbers
before 2008.
There is a lot to be said on this topic and we'll continue it more in our next post with information about adoption of H.256/AVC encoding. To learn more about Telarity and our video compressors,
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