[mythtvnz] Question about quality from satellite

[Nick Rout]

On Sat, Jul 13, 2013 at 5:40 PM, Stephen Worthington <
stephen_agent at jsw.gen.nz> wrote:

> On Sat, 13 Jul 2013 08:00:28 +1200, you wrote:
>
> >On 12/07/2013 22:24, ajp at cantabrian.co.nz wrote:
> >>
> >> Hi,
> >>
> >> I have recently upgraded my frontend with it now capable of full HD
> >> and it's great.
> >>
> >> I only record satellite in and it seems some recordings appear to be
> >> higher resolution or better quality than others. I am kinda theorizing
> >> that the good recordings are ones that are actually going out to
> >> terrestrial as full HD and obviously scaled back to SD because we
> >> don't do DVB-S2 yet -- but it's just a theory J
> >>
> >> Anyone know any more or have any pet theories like I'm imagining it J
> >>
> >> Thanks
> >>
> >>
> >>
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> >Quite correct - Sat. here is 720p while terrestrial is 1080(i - I think).
> >
> >I can see the differance and it's quite annoying since my "system" was
> >configure for DVB-T, but we moved into a rental that had Sky and very
> >bad analog....
> >
> >If you want that in writing, google "Optus D1" :)
>
> Some Sky channels are HD if you pay them extra for an "HD ticket".  I
> am not sure of the exact format used as I do not pay Sky extra for
> that, but they are broadcast on DVB-S2 transponders rather than DVB-S.
> But the rest of the Sky channels are SD and MPEG2 video rather than
> the much better H.264 video used on DVB-T.  They are definitely not
> 720p = 1280x720 - the ones I watch are mostly 576i = 720x576
> interlaced, or 704x576 interlaced.  720p is the lowest format
> considered to be HD, although a lot of 720p broadcast programmes are
> not actually HD - the source programmes have too low a bit rate.
>
> On DVB-T, TV One and TV2 are 720p.  TV3 is 1080i = 1920x1080 but
> interlaced ie half the resolution of 1080p.



No TV1 and TV2 are 1080i as well (they started as 720p I think but aren't
now)


> The other DVB-T channels
> are 576p, but with H.264 video so they are capable of rather better
> than the Sky DVB-S channels if the source materiel is good enough. The
> Sky DVB-S channels are limited by their older MPEG2 video format - Sky
> can not change to H.264 without replacing all the old set top boxes.
> MPEG2 video is rather less capable than H.264 in the same bandwidth,
> but it does an OK job for SD source materiel, but less so on Sky's
> 576i than if they were using 576p.  But even then, some Sky channels
> use lower bandwidth than others, so you get lower quality video.  I
> have some programmes recorded digitally from Sky DVB-S that are just
> 1.3 Gibytes for 60 minutes, and others that are rather larger, up to
> around 1.65 GiB.
>
> I do not record the Freeview channels from DVB-S so I can not say for
> sure what they are all broadcast as, but for testing purposes I do
> have TV One set up on DVB-S so I did a short recording just now and it
> is broadcasting as MPEG2 video (not H.264) inside an MPEG2 transport
> stream container.  But the video is 567p instead of Sky's 576i so
> better quality is possible.
>
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