[mythtv] s-video input / widescreen tv ?

[Laurent Farcy]

Erik Arendse wrote:
> At 20-1-03 11:41, Laurent Farcy wrote:
> 
> 
> Two seperate questions in fact:
> 
> A) does the tuner recognize the widescreen code, and can the TV output 
> add it to the generated signal again?
> Simply stated: No. Several standards exist to signal a widescreen 
> transmission, first tell me which one is used by your cable box. If it 
> has SCART out (should have as SCART was invented by the French :-) one 
> pin normally is used to indicate anamorphic signal.
> I know of no TV-in card which can detect that, but it would be easy to 
> build yourself (just connect to a LPT in-pin and read the line)
> Output can be done the same way on the outgoing scart pin.
> Other standards are used in the US (signal is transmitted alongside the 
> CC title data) and in Europe alongside the VPS/VideoText data. Detecting 
> those is no problem (especially when I finished subtitle support for 
> MythTV), but sending them on a videosignal again is (I don't know of any 
> software/hardware yet which can do that).

I didn't know there was no standard for signaling a widescreen 
transmission. Apparently, since I live in France, it must be the SCART 
pin 1 you mention.

Let's say, it would be a plus if the widescreen transmission signal 
could be sent. But I can still switch my tv to full widescreen if tv-out 
is anamorphic.

> 
> B) can you record/play anamorphic?
> Yes, no problem. Anamorphic just means you squash the image into 4:3 
> when transmitting it, it is only handled by the camera and the final 
> display, any transfer channel in between (and myhtTV in this case is 
> just a time-delayed transfer channel) just had to pass it along the data 
> unchanged. As a user-aid a 1-bit flag is included to indicate the 
> anamorphic format.

great news. Even though, there are a few channels which broadcast 16:9 
programmes :-\

> If you can detect the flag correctly you can even flatten the display of 
> the XV window on the computerscreen.
> 

Not sure I understand what you mean. But since, I haven't yet built and 
played with MythTV, let's move forward .

> 4/ Last, I'm wondering if there's a difference in terms of quality 
> between tv tuner cards for video grabbing, and particularly in my case 
> for s-video input grabbing. The differences could be, I guess, on 
> maximum resolution, visual quality, widescreen handling, ... So if you 
> could share your experience, I would appreciate your feedback.
> Max resolution is fixed for any PAL or NTSC standard. You can't grab any 
> more lines then are transmitted, you just have to accept TV was meant 
> for a V screen. If you have satelite or cable, perhaps you can grab some 
> digital channels, they are not limited that way, but MythTV just 
> supports analog TV tuner cards (for now???).
> 

So there are some limitations in quality due to the source itself. But, 
for a same video source, are there some differences in terms of visual 
quality between one tv tuner card and another ? Maybe some cards have 
better decoding chips ?


> Erik
> 

Thanks very much Erik.

Laurent
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