[mythtv-users] What's the point of MythTV HD?

[Michael T. Dean]

On 12/04/2007 03:20 PM, ryan patterson wrote:
> On Dec 4, 2007 10:55 AM, Michael T. Dean wrote:
>> I'm pretty sure that ivtv supports Widescreen Signaling (WSS) to allow
>> the capture card to capture the video for widescreen display (i.e. using
>> all the pixels for image content), so I know it can be made to work for
>> output from an STB.  It's possible that it may require some
>> modifications to the driver as the STB may not be using WSS proper or
>> ivtv may only currently support WSS in PAL (since it's not used often in
>> the US), but...
> IVTV does not need to support any special feature (like WSS).  You (the
> user) must simply select the correct aspect ratio for the recording to play
> correctly on your TV (hint: press the W key during playback).
>   

Yes.  There's nothing quite as nice as being forced to manually do
something that should be done automatically.

The idea is to ensure that ivtv includes the aspect ratio information in
the MPEG stream so that the MythTV player will automatically display it
properly.  If you were thinking of making it "automatic" by setting the
aspect override in Myth, try to explain to users with multiple different
video sources which require different aspect ratios how this will work.

> Simply tell you set top box to output an anamorphic image and then have
> mythtv stretch the image to correctly fit your TV.
>
> WSS (wide screen signaling) is a PAL proprietary system developed to protect
> copyrights among other useless things.

Strange, really, that NTSC lines 20 and 283 carry 14 bits of data,
including 2 data bits that specify the aspect ratio of the image and
whether or not the image should be letterboxed.  (See
http://www.intersil.com/data/an/an9716.pdf and/or the book Video
Demystified and/or IEC 61880*)  Then there's also the +5V offset on
Chrominance for S-Video (though I'll grant that that's not widely
supported by most consumer electronics equipment).

>   Please keep it on your side of the
> pond.

Since I'm in the US, it seems it is on my side of the pond, but I know
it's also over in Europe--where you wanted it to stay.

Mike


* IEC 61880 is available at
http://webstore.ansi.org/RecordDetail.aspx?sku=IEC+61880-2+Ed.+1.0+en%3A2002
, if you want to purchase a copy.  It's $45.00 for non-members, but you
could get a copy of Video Demystified (with much more useful
information) for that same price.