[mythtv] Feasability of using software scalers in mythtv videoout

[Bryan Mayland]

I'm considering the feasibility is of replacing XV's hardware scaling to 
zoom video playback with what could be higher quality software scalers. 

My mythtv is hooked to a display with a native resolution of 720p.  I've 
spent some time experimenting with various methods of getting my 
recorded SD video (from a Hauppauge PVR card) onto this screen with the 
best quality possible.  I've tried running a 720p modeline and letting 
XV scale up as well as running a 480p modeline and letting the 
television scale up.  Both these aren't all that fantastic.  Tonight I 
sat down and juked with using a software scaler to resize the video.

Here are some results, taken with a digital camera of the television (I 
found this easier than doing a framegrab, I hope that's ok).
XV Resize
http://capnbry.net/~bmayland/fi/pvr150/resizetest1_xv.jpg
http://capnbry.net/~bmayland/fi/pvr150/resizetest2_xv.jpg

Software Resize (Lanczos)
http://capnbry.net/~bmayland/fi/pvr150/resizetest1_lanc.jpg
http://capnbry.net/~bmayland/fi/pvr150/resizetest2_lanc.jpg

Ignore the jpeg artifacts, the pngs were a meg each, but note how much 
better picture quality you can get with the software scaler.

So if this were implemented as an option, would it be something that 
would be accepted into svn?  Also, other than increased CPU usage, what 
other advantages and disadvantages are there?  I know there is already 
zoom and filter support in videoout, but this would take that one step 
further I think.