Hd Bandwidth ?
 

just how much extra space does an hd recording take up? ,I was under the impression it was 3 times as much as standard but i recently recorded a 2 hour film and it took up a whopping 11 hours space on the disk.:(

Re: Hd Bandwidth ?
 

I guess you are talking about National Treasure or Indiana Jones. I recorded them both, never seen the free space indicator on the V+ say 'Critical' before. I also thought it was between three and four times the space requirements of SD-I wonder how accurate the free space indicator is.

Re: Hd Bandwidth ?
 

V+ can handle 80Hrs recording in SD and 20Hrs in HD

Re: Hd Bandwidth ?
 

I noticed National Treasure took up a whooopin 9 hours - that makes it about 4 times the space - actually i remember reading somewhere that HD does deliver 4 times as much information - so that would be about right & tallies with darthlinux findings

Re: Hd Bandwidth ?
 

HD
720p = 1280*720 = 921,600 Pixels
1080i = 1920*1080 = 1,382,400 Pixels
SD
720*480 = 345,600 Pixels < for information only - US format
720*576 = 414,720 Pixels

1382400/414720 = 3.333 times more data in an HD image
Transitions, encoding level of action will then also impact the size of the file etc.

Re: Hd Bandwidth ?
 

not very accurate I suspect

Re: Hd Bandwidth ?
 

Also bear in mind most of the SD is variable bit rate (VBR), whereas the BBC HD will be constant bit rate (CBR) of around 18Mb/s.
I dont know what Virgin use for their HD VOD bitrates, but the SD VOD was done at 2.9Mb/s (CBR) from memory.

Re: Hd Bandwidth ?
 

Thats a lot of Bandwidth for BBC HD when you consider HD DVDs run at a maximum of 30Mbit/s

Re: Hd Bandwidth ?
 

Thats MPEG2 for you, HD requires a lot of bandwidth! As Virgin are encoding a single channel and its MPEG2 HD then theres no room to stat mux, so they have to use CBR.

A single qam64 channel carries just over 38Mb/s so its not that much really, still plenty of room for a few SD channels.

Not sure what level and profile is typically used for HD DVD's - but level 4 for main profile defines a max of 20Mb/s - level 4.1 at main profile allows upto 50Mb/s to be used. Also bear in mind Virgin encode realtime with effectively a single pass best effort encode, DVD's are encoded non-realtime and for difficult scenes the encoding can be tweaked to provide the best results on a scene by scene basis.

Re: Hd Bandwidth ?
 

I was also looking at it vis a vis the 4 times the data so compared to an SD channel of 3Mb/s that would be 12Mb/s and they have a spare 6 Mb/s capacity there.

Those numbers are huge. That means I am getting 40*(say mid point of 15) Mb/s of HD content pushed down my cable here. Thats over 600+Mb/s. Then the 100s of SD channels also!

Re: Hd Bandwidth ?
 

12Mb/s HD on MPEG2 would not be particularly good. H.264 HD is reasonable at those rates, but would still demand more for difficult scenes.
Virgin had at least 27 streams of over 38Mb/s each over 3 years ago so the numbers are feasible.