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Posted by Little Red Hen on 12/13/06 10:57
"Jukka Aho" <jukka.aho@iki.fi> wrote in message
news:UYNfh.772$vn3.405@reader1.news.saunalahti.fi...
> Max Haltermann wrote:
>
>> Thanks for the pointer re aspect ratio terms.
>> As I wrote in my first posting, the transmitted signal of all local
>> DTV stations has 4:3 images embedded in a 16:9 transmission. Format
>> 12P16
>> VideoRedo File info says 16:9 and image 720:576 (normal PAL format).
>>
>> This makes sense for the DTV stations, as this way they provide both main
>> aspect ratios for the end user.
>
> It doesn't make too much sense to me - and that's exactly why I asked for
> a clarification. :)
>
> You're hailing from .au, and you're using the same DVB standard for
> digital tv as we do here in Europe. The DVB standard allows aspect ratio
> signalling: pictures can be sent in 12F12 format or in 16F16 format and
> signalled respectively.
>
> My local stations send their programming in their original full-frame
> format (be that 12F12 or 16F16), without adding any bars. While doing
> this, they also signal the correct aspect ratio. The tv set (or the DVB
> viewer program on a computer, if you're using a DVB tuner card)
> auto-switches the aspect ratio according to this signalling. The benefit
> of this approach is that the viewer will get the full original resolution
> all the time, without having to deal with compromised downsampled images
> with the black bars and loss of resolution.
>
> (Granted, sometimes you'll see 12P16 segments within a 16F16 programme, or
> 16L12 segments within a 12F12 programme, but they're usually just short
> inserts that were sourced in a different format - archive material, for
> example - and not the main bulk of the programme.)
>
>> So the question still is: How can one get a full hight and full width 4:3
>> display from the raw digital TV transmissions on to DVD
>> or onto a TV screen, seeing there is no D/A conversion or decoding
>> involved?
>
> Another poster already suggested using IFOEdit and applying the "pan &
> scan" feature [1] of the DVD-Video standard. This sounds like a good
> solution to your problem as it doesn't require re-encoding the image.
> (Since the active area of your 12P16 image is centered and nothing happens
> outside that center area, you don't need to actually define any pan & scan
> vectors. Just switching the mode on will be enough.)
>
> If the 12P16 MPEG stream is flagged this way - as "pan & scan" material -
> and if the DVD player is set up for a 4:3 display, this method will (or at
> least should) create a centre cut-out of the 12P16 picture and zoom it to
> cover the full screen.
> (In other words, the player will convert the image back to its original
> 12F12 format, on the fly.)
>
> The horizontal resolution that was lost when the station originally
> converted the 12F12 picture into a 12P16 format will unfortunately stay
> lost forever. But at least you'll get a full-screen picture on a 4:3 set
> instead of a postage stamp with black borders on all sides.
>
> _____
>
> [1] See <http://www.dvddemystified.com/dvdfaq.html#3.5> and the paragraph
> that begins with "For automatic pan & scan mode..."
>
> --
> znark
>
It's an old article (1999 )
http://www.fxj.com.au/announcements/apr99/digitaltv.htm
but it sums up Australia's non standard implementation of DTV, like 576p is
regarded as HDTV etc. The stations only transmit in 16:9 and all 4:3 old
movies are pillarboxed with in the 16:9 frame (always). There is currently
no datacasting and only the HDTV muxes have Dolby 5.1 (sometimes depending
on the prevailing weather in Antarctica on a Wednesday if you get my drift)
the SD muxes all have MPEG sound and some stations Dolby Stereo. Subtitles
are via Teletext for one major network but not the others.
A more convoluted way of solving the OP problem is to use ProjectX and
untick SED and then run the remuxed program through a fixmpeg program. Down
here and certainly members of the Topfield fraternity use the IFOEdit method
and is outlined on a number of FAQ and AQA threads. Regrettably Australian
politicians have a habit of 'modifying' international standards from AM
broadcasting, FM, TV (we had a ch 0 and a channel 5a in the TV analog
spectrum) etc etc. Even in the professional world of wireless microphones
the allocations are 'shifted' slightly. Sorry I'm feeling a bit bleak
tonight....
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