[linux-dvb] Re: hdtv & dvb

[˙so-8859-1?B?SORt5GzkaW5lbiBKb3Jp?˙jori.hamalainen@teliasonera.com>]

> > > It's only broadcasting HDTV demo loops, though. But in contrast to
> > > EURO1080 this service is broadcasting "true" 1080i at 59.94
> > > fields/sec, whereas EURO1080 uses an uncommon 50 fields/sec.
> >
> > Wouldn't 50 fields/sec simply be the PAL rate?
> 
> Hmm, ok, I can see how stations who have huge archives of PAL material
> might want to use 50 fields/sec HDTV for easier conversion. 
> But EURO1080
> isn't such a station, so I don't see why they chose this. In 
> fact, most
> HDTV material available today will likely be 59,94 fields/sec, so IMHO
> EURO1080 made a pretty stupid decision, since they cannot 
> easily purchase
> HDTV shows e.g. from the USA and just broadcast that.

I would say that HDTV isn't limited to any refresh-rate. All devices saying
to be HDTV support all HDTV framerates. Similar to current televisions
supporting PAL-50&PAL-60 for NTSC emulation.

HDTV @ 50Hz is refresh-rate for upscaling easily the old 50Hz material.
But tv-sets supports HDTV @ 60/1.001 and HDTV @ 60.

It is a shame that ATSC didn't specify 50Hz refresh rates for 720p / 1080i.
Now we have to wait and see what kind of standard Europeans make.

My studies with HDTV and my beamer shows following formats (Sony beamer
supports 720p@50,60, 1080p@24, 1080i@48,50,60):

720p & 1080i modes run always with 74.25MHz pixel clock (both 'NTSC' and 'PAL'
but it is HDTV, a new standard, not those 'old color standards'). Other possible
HDTV clocks are 13.500MHz and 27MHz.

In 720p mode screen resolurion is 1280x720.

Now comes the differences:
Line length specified by ATSC (SMPTE 296M) is 1650 pixels for ~60Hz
S3 HDTV white paper suggests HDTV @ 50Hz to use 1980 pixel line.
Syncs are similar 40/80 pixel syncs (haven't been able to determine
which is better). So a lot empty pixels after sync.

Screen heigh for both formats are 750 lines with 5 line syncs.

Well X11 modelines I am currently testing (not happy with overscan):

Based on SMPTE 296M-2001 HDTV-standard for Sony VPL-HS10 by Jori Hämäläinen, www.jori.ws!
Modeline "1280x720_60.00"   74.25  1280 1352 1432 1648 720 725 730 750
Modeline "1280x720_50.00"   74.25  1280 1680 1720 1976 720 725 730 750 # 40 pixel sync test
Modeline "1280x720_30.00"   74.25  1280 3000 3080 3304 720 725 730 750
Modeline "1280x720_25.00"   74.25  1280 3660 3740 3960 720 725 730 750
Modeline "1280x720_24.00"   74.25  1280 3824 3904 4128 720 725 730 750

Concept image of my project setup is at: http://www.jori.ws/hdtv_htpc/htpc.jpg
(Yeah, VGA image is a ATI card, but currently using Nvidia card because
ATI has serious problems with DVI-output to my projector).

> Aside from that, I don't think there is any digital HDTV 
> standard with 50
> fields/sec, while the ATSC HDTV standards exist and are well 
> established.

Australian AS4933.1 standard specifies a lot of timings according to Quantumdata
papers (why aren't those standards free??) but yet I have to see what timings
are the best for my beamer.

Best regards, Jori Hämäläinen

BTW: Euro1080 shows also shows, see www.euro1080.tv


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