720x576 TV-out with Chrontel 7007
 

Please see this thread in the NVIDIA Legacy Graphics Cards forum:
http://www.nvnews.net/vbulletin/showthread.php?t=69119

Re: 720x576 TV-out with Chrontel 7007
 

IMHO the ideal TV-OUT configuration would be to always configure 1:1 scaling in the encoder, generate a modeline that provides the resulting horizontal and vertical resolution (depending on TV standard), and offer the user some way to set the borders of the visible area depending on the overscan characteristics of his TV set (e.g. by tweaking the modeline using xvidtune or similar).

The result would be an odd resolution, but at least there is no unnecessary scaling involved.
I think the current solutions (to go via a "standard" resolution like 800x600 and then scale it and add fixed borders) are inherited from the Windows world, where users and some software expect standard resolutions.
There is no such situation in Linux, I have always used "nonstandard" resolutions under X, e.g. to make the pixels square and have the best achievable resolution on the monitor I happened to own.
This is possible on VGA by tweaking the modeline, and it would be nice if the same was possible on TV-OUT.

(fortunately my current TV has VGA input so I no longer have to fight this war)

Re: 720x576 TV-out with Chrontel 7007
 

The problem is that tvout encoders can only output certain modelines. Some modern encoders are a bit more flexible but older ones like the chrontell only support a fixed number of modes. In general standard modelines won't work for tvout encoders (and the drivers ignore those; it appeared to work a bit in the past but it didn't really work) If you want to access the chrontell chip yourself you could play with nvtv (http://www.sf.net/projects/nv-tv-out). The tool can access the i2c bus of the card and also the tvout encoder.

Re: 720x576 TV-out with Chrontel 7007
 

The problem are not the capabilities of the encoder chip, but the modeline generated by the nvidia driver.

The CH7007 mode 19 wants 800 horizontal pixel. The driver configures the geforce2 chip to send only 720.
In modelines it should be
modeline "800x600" 29.5 800 ... ... 944 600 ... ... 625
or (to not exceed the visible region)
modeline "768x576" 29.5 768 ... ... 944 576 ... ... 625
but the driver uses
modeline "720x576" 29.5 720 ... ... 944 576 ... ... 625
resulting in black borders on the sides.