All posts by Alphathon
Below are all of Alphathon's postings, with the most recent are at the bottom of the page.
@MikeP You appear to have a little confusion here. Analogue PAL SDTV is indeed 625 interlaced lines, but 49 of those lines do not contain image data (used to control old CRTs etc). Digital SDTV on the other hand doesn't need these extra lines so is 576i. Current HDTV in the UK is broadcast at 1080i50 (1080 "lines" of vertical res). You also seem to have muddled up the frame rate somewhat. The 50Hz of SDTV is the field rate, and is equivalent to a frame rate of 25fps since it is interlaced. This is also true of 1080i50. In some parts of Europe (e.g. Germany) they use 720p50, which is also 50Hz, but the fact that it is progressive means it also has 50fps.
According to Wikipedia, while HD-MAC (i.e. 1250 lines - 1152 of which were picture data) was recorded at 20481152p50 (50fps), at the receiver side the output was actually 14401152i50 (25fps), so slightly higher vertical res but lower horizontal res than current broadcast HDTV (19201080i50, although sometimes 14401080i50 has been used). Current HDTV thus actually has 1.25 times the number of pixels as HD-MAC at the same frame rate.
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How likely are these muxes to come to other transmitters and for what (technical) reason are some main transmitters left out? In my case I'm served by Knockmore, which according to this site has both C33 and C34 free, so why aren't they being used to carry these muxes? Thankfully we have a dish set up in addition to the aerial, so we should be able to get the new channels that way. We won't however be able to use them on our YouView DVR.
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I don't know if this is news to you lot on here, but BBC Four (along with CBeebies) appears to have just launched in HD on satellite (11024MHz H). I cannot attest to CBeebies (which is apparently on SID 8931) since it is off-air, but I've tested SID 8932 and it certainly appears to be showing what is currently on BBC FOUR but in HD.
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Monday 7 January 2013 8:57AM
I don't know if this is the right place to post this or if you know already, but it would seem BBC One Scotland HD (and possibly BBC One Wales HD) are launching next Monday (14 January 2013).
Last night, I noticed that the 2 simulcasts of BBC One HD on Astra 2F 11024MHz Hor. suddenly got Freesat guide data corresponding to the programming on BBC One Scotland (SID 8901) and BBC One Wales (SID 8911). However, while the guide said otherwise, the video for the local news slot was still "this is BBC One HD".
This morning, however, I checked forward on our YouView (Freeview HD) box and its guide suggests that Reporting Scotland (Scottish local news program) will be shown from Monday 14 Jan, so I suspect that is when the transition will happen, and the Freesat guide data is simply pre-emptive. Can anyone else confirm this (especially in Wales)?