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BBC Lowers HDTV Bitrate; Users Notice
aws910 writes "According to an article on the BBC website, BBC HD lowered the bitrate of their broadcasts by almost 50% and are surprised that users noticed. From the article: 'The replacement encoders work at a bitrate of 9.7Mbps (megabits per second), while their predecessors worked at 16Mbps, the standard for other broadcasters.' The BBC claims 'We did extensive testing on the new encoders which showed that they could produce pictures at the same or even better quality than the old encoders ...' I got a good laugh off of this, but is it really possible to get better quality from a lower bitrate?"
The main change in the past year has been the psy optimizations that were added; before the psy optimizations, x264 was roughly on par with Mainconcept, one of the better commercial encoders. The psy optimizations--adaptive quantization and psy-RD (both on by default)--put x264 way over the top. Recently, the new MB-tree algorithm (also on by default) has boosted quality quite a bit as well. The main catch with psy optimizations is that they're nearly impossible to measure mathematically, and in fact, unless you disable them, they will make the "mathematical" measures of quality (mean squared error/PSNR) much worse.
It's always nice when free software solutions trash the commercial alternatives.
In the US, Comcast uses codex compression to squeeze HD on their cable systems. When people get to see native resolution at the TV store, then get the Comcast version when they plug in their shiny new HD TV, they wonder WTF? That the beeb would put their foot on the garden hose and expect no one to notice is ludicrous.
I wish the FCC would get involved in the US to force cable companies to limit the number of channels supported and broadcast them in the highest sustainable resolution-- or tell their users the truth about what's happening and why. Maybe we can start to get rid of the excess junk channels.
---- Teach Peace. It's Cheaper Than War.