SageTV 2.0.15 Chan overlay font too small for TVs, > 4 MHz BW NTSC of stand. required

[rak306]

I don’t want to throw stones, and I understand SageTV 2.0 features are frozen until release, (which I 100% agree with) but:

The Channel overlay that is displayed when you change channels (e.g. up), have fonts that are too small to display correctly using composite video on a standard NTSC TV. Figure 1 shows a “PC screen capture ” (not a TV) of a typical overlay. Figure 2 is a 400% blowup of a small section of the screen.

Clearly visible is that the font is only 1 pixel wide, and has no antialiasing. (Note: the antialiasing of the up and down arrows).

The pixel sample clock for TV is 13.5 MHz when using 720 x 480.

A signal going from white to black (or dark blue, in this case) and then back to white, in one pixel (the r for example in Crusades), has a large component of 6.25 Mhz bandwith. NTSC signals for broadcast television are limited to 4 MHz bandwidth.

Conventional (Not HDTV) TV receivers vary greatly in their ability to decode NTSC composite signals. The best of them have near 4 MHz bandwidth, but it is not uncommon for TV sets to have only 3-3.5 MHz luminance bandwidth.

What happens when a typical receiver gets this > 6 MHz signal? The letters are smeared, ring, and color rainbow interference patterns show up (depending on the color decoder in your set). This makes the text largly unreadable.

S-Video, using Y/C connector is another story, as the luminance has its own cable, and can have higher bandwidth than 4 MHz.

But using a video output device like the PVR-350, any TV should be able to be connected to SageTV, and I suggest that only HDTVs (or computer displays) will look acceptable with the current overlay, and then only when using S-video or component video.

In contrast, Fig 3 is a digital camera picture (of my TV screen) of my local cable guide. Note: this works on all TVs, contains a lot of info, and is very readable.

Bottom line, as I see it:

SageTV channel overlays have bandwith requirements in excess of the NTSC TV specification meaning they won’t display correctly on most TV receivers. That is a pretty bold statement, but I believe it's true.

I suggest that the developer needs to take a look at this. The obvious answer is to use larger, antialiased fonts. This probably means limiting the information displayed, but when rapidly changing channels, the only necessary info (IMHO) is the channel number, TV call sign, and program title. Once on a channel, a simple info push could bring up all of the info for the program
(using the entire display if necessary).

(Note: I could be wrong. will not be held responsible for anything I say. Your mileage may vary, checks will not be honored.)

Rick

PS (1st time I've tried inserting pict. hope it works)

[m0ng00se30]

Interesting post... rak!

Just thought I'd add my observation (not nearly as technical)

I haven't really noticed a problem reading the overlay. I am using composite to a 7yr old 32"Sony tv from what I consider normal viewing distance 8-12'.


--Mike

[falchulk]

I have had sage on a 32" TV and now a 55" tv. I can read everything crystal clear. The 32" tv was 12 feet away and my 55" is 15 feet at the closest watching point. I and many others have had no problem using svideo with sage for months, and some for a year.

[mlbdude]

I think the fonts are too small, but I can read them.

[rak306]

falchulk wrote:

"I have had sage on a 32" TV and now a 55" tv. I can read everything crystal clear"

Those are TV monitors, which likely have very good decoding. I'm talking about meeting NTSC standards, so that all TVs will work.

."I and many others have had no problem using svideo with sage for months, and some for a year."

S-video is not the problem, composite is. 1.4 is not the problem, it uses bigger fonts. The problem is with 2.0 (which hasn't been out for a year). (More specifically 2.0.15, I haven't tried any 2.0 versions before that).

Rick

[falchulk]

You might have me there. I have not had .15 on a TV. Miy 55" went down a few days before .15 was released. I am currently using a 20" LCD monitor. Prior to this, I have not had that problem with any of the betas.

Mlbdude, Studio will let us change the font sizes correct?

[fidget]

When Beta 15 first came out, I filed this as a bug. You may want to do the same.

[rak306]

I need to revise my statement. This is really a problem specific to the PVR-350. If you are using TV out on your computer, you may not see this. I'll explain.

When using the PVR-350 (the only card that 2.0 STV supports for OSD), the overscan of your TV will need to be accomodated by adjusting the video size (using setup) so that the menus fit on the screen. When I did this on my setup, the fonts switched to a smaller size, to fit on the screen. If you are using TV out, this likely does not happen, and you have the larger fonts.


However, for me, I the PVR-350 is the only way to get acceptable video quality (with OSD) to my large screen TV.


Rick