[mythtv-users] Recommendations for front end replacement
mythtv-list at dinkum.org.uk
Tue Dec 6 09:02:13 UTC 2011
On 6 Dec 2011, at 08:37, Tim Draper wrote:
> On 6 December 2011 08:14, Kevin Ross <kevin at familyross.net> wrote:
>> On 12/05/2011 03:36 PM, Mark Carbonaro wrote:
>>> No problems running 1080p with vdpau high profile
>> Yes, but how about 1080i?
> unless i've misunderstood something with the various formats, it's as
> simple as 'p' required more processing than 'i'.
> so...1080i uses half the bandwidth of 1080p
Sadly that's not the whole story.
1080i needs de-interlacing for any flat panel display and pretty much for any myth system, de-interlacing is a far more resource hungry process than decoding mpeg2 and maybe even h264 in some senses. With vdpau there are some excellent de-interlacers provided your graphic card has the capability, for sports, news and any other live TV you need advanced 2x de-interlacing but if you only ever watch films or drama on TV then you may be able to get away with one of the 1x spacial or advanced de-interlacers.
If you have a smaller TV <40" and no-one in the family is especially aware of or sensitive to motion problems in TV then you may not notice the difference, everyone's eyesight and perception is slightly different this is why you will get some posters telling you an ION is great and others (like me) telling you to buy a GT220 or GT430 or everything will look terrible.
The issues are also the sort of thing that some people can miss entirely until it's pointed out after which time the problems cannot be unseen! If a broadcast engineer wants to be cruel to you they can point out a whole host of unpleasant effects in modern TV that might put you off watching TV for life ;-) I sent my new girlfriend out of the room while setting up her new TV as she was wanting me to point out the problems I was fixing as I went along, sometimes ignorance is bliss!
1080p encoding often uses higher bandwidth when compressed, mostly because it has usually come from a bluray but in some cases lower bandwidth 1080p (from some satellite & cable feeds) can be harder for the decoder. Due to this one posters "1080p/i works for me" is pretty meaningless unless [s]he's watching the same sources as you recorded in the same way.
While it's true that 1080i uses half the bandwidth of 1080p when uncompressed, pretty much any 1080p you find outside of a broadcasters R&D lab uses exactly the same bandwidth as it's 1080i equivalent, potentially a little less. Uncompressed bandwidth is irrelevant for anything other than very long HDMI cables or de-interlacing.
> in other words - no problems :)
> my 330ion handles 1080i broadcast material fine; I've not tested 1080p
> yet though.
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