Image Processing Reference
In-Depth Information
the operating system, making it a good format to choose. This argument was called into
question by the Frost & Sullivan findings that Windows Media and QuickTime have a
roughly equal share while Real Networks trails some distance behind. But none of them
has anything approaching a 97% installed base.
There are no reliable statistics on what people actually have installed. The arguments
are also unreliable, because market share figures and installed base are not the same. So,
many of the assumptions are simply not reliable enough to state authoritatively that most
people use a particular player and codec. There is no substitute for doing your own
research and surveying your target user base properly.
Codecs of a similar vintage will generally deliver about the same performance under opti-
mum conditions. Note the word “generally” and the word “vintage.” MPEG-2 is clearly
not going to deliver similar performance to H.264 and WM9. But WM9 and H.264 are rea-
sonably similar in performance. There are some minor differences between them, and
there will be compression tools that are available only for one or the other. But you will be
able to put HDTV onto a DVD disk with either codec, and you can compress SDTV for
around 1.2 to 1.5 Mbps.
Choosing Open Standards
A good strategy is to look at an open-standards approach. Your preferred player may sup-
port some open standards anyway, so if the player is the overriding technology selection
criterion, opting to use an open-standard video codec rather than the proprietary one may
be a good compromise. An example of this might be to select the QuickTime player but
elect to deliver H.264 video. Of course, that is oversimplifying things, and you must
ensure that the profile and levels are compliant as well.
Open standards imply choice of suppliers for each part of the end-to-end
process, and therefore they prevent lock-in.
Because you are using open-standard video codecs, you don't have to purchase
your encoder from the same company as you did the player. This allows you to test a
range of encoders to see which one produces the best quality for the smallest file (for
downloads) or lowest bit rate (for transmission/streaming). As long as the profiles and
levels selected are standards-compliant and your player copes with them, you will gain
some strategic advantages. Components within your system can be replaced with alter-
natives as new and higher-performance versions are delivered, and you will completely
avoid the lock-in associated with a proprietary solution.
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