On Sun, Dec 05, 2004 at 10:26:23PM +0100, Ramon Clout wrote:
> First of all, congratulations on the great work for the ivtv driver.
>
> I've encountered a minor problem for PAL output via the saa7127:
> black level is set to 0x23 (=37.8IRE), which gives a picture that
> is too dark. For a black level at 43IRE (?PAL standard?), the black
> level register (5D) should be set to 51=0x33 (according to the
> data sheets this is also the recommended value). Next to that, it
> also gives much nicer results.
>
> The following change to saa7127.c, line 201 (0.2.0-rc3 release)
> should do the trick:
> {SAA7127_REG_BLACK_LEVEL, 0x23},
> ->
> {SAA7127_REG_BLACK_LEVEL, 0x33},
Cool, I'll change that.
>
> For NTSC, the difference between recommended values in the data sheet
> and saa7127.c is much smaller:
> 0x39 (=47.0IRE) and 0x3a (=47.3IRE), ?spec=47.5IRE?.
I actually adjusted this according to a waveform monitor, was awhile back,
but also we are using the 7.5 IRE setup level too so may be tuning or that
which made this value not exactly what the datasheet recommended (possibly
change from actual in-use on a card and adjusted for other components altering
the actual output level slightly). I need to go through this all though
again on the waveform since it was when I first was playing with the card
and could need some fine tuning :-) (also the U/V levels are for the RGB output
which is the OSD I believe, not the video encoding output).
Thanks,
Chris
>
> I'm no video expert, so can someone please take a look at the data
> sheets and check these numbers (also the GAINU & GAINV)?
> (you may have to use the saa7129 data sheets as the saa7127 is
> no longer available)
>
> Thanks,
>
> _Ramon
>
>
>
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--
---
Chris Kennedy / [EMAIL PROTECTED]
Engineer KMOS-TV/KTBG-FM
Broadcasting Services Department
Central Missouri State University
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