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

Michael T. Dean mtdean at thirdcontact.com
Tue Dec 4 15:55:55 UTC 2007


On 12/03/2007 11:18 PM, George Mari wrote:
> David Linville wrote:
>   
>> On 12/3/07, Brad DerManouelian <myth at dermanouelian.com> wrote:
>>     
>>> On Dec 3, 2007, at 11:19 AM, James Gutshall Jr wrote:
>>>> "downsampled content via SVideo"
>>>>
>>>> Doesnt this, by definition change the content to NOT HD?  
> Yes, by definition.
>
>   
>>>> I agree that it provides a way to watch the channel, but for some, the the
>>>> HD channel is also available in analog, thus the problem isnt
>>>> watching that particular program.  the problem is that we want to
>>>> record, and watch later, the program in question.... in HD quality.
> I would like to record it and watch it in HD quality as well.  But my 
> service provider doesn't allow it.  It bothers me, as I feel that if I'm 
> paying a monthly fee for an HD receiver, I should be allowed to view 
> that content as I wish.
>
> [deleted]
>   
>> Wouldn't you end up with black bars on the top and bottom recording that
>> way?  If so that would kill quite a bit of extra resolution.
>>
>>     
> The best resolution you can get this way is wide-screen 480i.  This is 
> the same way anamorphic DVD content works.  You  takes a 16:9 content 
> stream, send it out your STB S-Video output, it gets squished 
> horizontally to record at 720x480 pixels (4:3 aspect ratio) by analog 
> tuner/encoder card, and stretched back out horizontally by MythTV to 
> it's proper aspect ratio.  The only difference between this and 
> anamorphic DVD is that DVD content is usually 480p (progressive) versus 
> 480i (interlaced).
>
> I just researched all this a few weeks ago when I upgraded from SD 
> DirecTV to HD DirecTV.  The High-def DirecTV set top boxes (Dish too, 
> probably cable boxes also) let you set the format of the signal being 
> sent out any of it's outputs.  You tell it whether you have a 4:3 or 
> 16:9 TV, and you tell it how it should display programs that don't match 
> the aspect ratio of your TV - letter box, pillar box, squished 
> horizontally, etc.  You can even cycle through the formats with a button 
> on your remote.
>
> I get better results with Widescreen 480i than I did stretching 4:3 
> programs to fit my 16:9 TV.  I see fewer artifacts, and just better 
> overall quality.  It's not HD, but it's better than 4:3 SD, at least to 
> my eyes.  Part of that could be that the DirecTV HD signal is less 
> overcompressed than the SD signal was, but whatever.

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...

Mike


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