[mythtv] Capture Card Resolution

Edward Wildgoose Edward.Wildgoose at FRMHedge.com
Fri Mar 21 11:53:41 EST 2003


>  > I have tested with 786 and it DOES seem to do something. I
>  > don't know how to check that it really IS recording at 768

> (turn off 'fixed aspect ratio' and press 'f' during playback
> to see the video at the actual recording dimensions...)

Hmm, well I will give it a go, but even if I turn my screen res down to 800x600 I think it will be hard to see the difference between 720 and 768 pixels?

Playing with screen res has actually shown up another bug in 0.8 CVS.  The setup screen which allows you to chance the size of the GUI appears to ignore numbers typed in to the height box by hand, however, it accepts the up and down arrows at the side.  To be clear, it lets you type stuff into the box, however, when you finish the setup screen and go back in the numbers are not saved.  This does not seem to happen to the width setting...  (What happened was I tried to set 800x600 and ended up with something which was correct width, but height was full size of the screen...)

I may have confused width and height in the above discussion, easy to see if you try it though.

> 
>  > though, however, I get video out of the thing (although it
>  > skips on my machine).  Quality is noticably higher than
>  > 640x480 actually.
> 
> Good enough. As long as the encoder library didn't spew errors
> and it didn't seg fault or fail in some other way, it's okay.

No errors.

> 
>  > ...However, there is a line which appears to be scaling
>  > bits/sec (something like "scale = (h * w) / (640x480);" and this
>  > I assume is not quite correct on PAL sets?
> 
> Not a problem. This would be the scaled bit rate. It just
> normalizes the bit rate to something. Greater than 1.0 is just
> as valid as less than 1.0. Once you find a bit rate you like,
> you can change the resolution without having to multiply the
> bit rate to get the same quality. This is just a relative scale.

Is that a reason not to change it though?  There is a prototype IF statement higher up the code, so it becomes something like:

	if type=PAL then
		scale = (h * w) / (768x576);
	else
		scale = (h * w) / (640x480);
	
Just a thought... (actually I think I may have misunderstood your point.  Please disregard if this is junk.)



More information about the mythtv-dev mailing list