Image Processing Reference
In-Depth Information
AVC Alliance and MPEG Industry Forum
It is a popular strategy for a group of interested companies and individuals to rally around
a new open standard and form a collaborative organization. This leads to better interop-
erability and helps to promote the new standard in order to get things off the ground.
The AVC Alliance as well as the MPEG Industry Forum are now promoting the
H.264/MPEG-4 part 10 standard and this will demonstrate to the industry that the partic-
ipating companies are taking the standard seriously.
Risks and Benefits of Adopting H.264
The H.264 codec has been selected for next-generation DVD formats and European HDTV
broadcasts so the risks of adoption are decreasing.
At this point in the MPEG-2 life cycle, bit rates of around 6 to 7 Mbps were being
achieved for consumer-quality video. The MPEG-2 coders have improved over the last
five years so that bit rates as low as 3.6 Mbps are possible with some compromises in qual-
ity. Envivio is aiming for a bit rate that will deliver H.264-coded video that is of excellent
quality at well under 2 Mbps, and experts in video coding are optimistic that the same
potential reduction of 50% of the bit rate is possible with H.264 over its life cycle (although
that remains to be seen, and you should be careful of being too optimistic when using
these values for capacity planning).
There is a risk that companies wanting to make an impact with AVC/H.264 encoders
will launch products with less-than-optimally implemented codecs. While the new codec
standard is becoming increasingly important, the software is entering the market more
slowly than people would like. This careful approach is not necessarily a bad thing, but
you should thoroughly test any codecs you purchase to ensure that they are interoperable
and are delivering the anticipated quality and bit rate. Always remember that the standard
defines only a legal bit stream for the decoder to process. How that was encoded is not
specified in the standard, and two implementations of the H.264 encoder may deliver very
different results even with the same parameter settings.
Implications for Linux
Let's examine this in the context of the Linux platform. There is no dominant de-facto stan-
dard on Linux and it welcomes all comers equally. The DivX codec, which is a derivative
of MPEG-4, is available as an open source.
Oddly enough, Linux is used in products such as TiVo, and in fact quite a few TV set-
top box manufacturers that are engineering interactive platforms are using a version of the
Linux operating system optimized for TV. Linux is a useful platform to build streaming
servers on, and certainly in the past it has been a very appropriate platform for building
Real Networks encoders. It is still very good but Mac OS and Windows have caught up
with it in the areas it dominated as an open-source platform. The H.264 standard would
work very well with Linux and, provided a suitably performing player is available, H.264
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