No colors @ Svideo @ i915

Dirk Thierbach dthierbach at
Mon Mar 19 00:30:24 PDT 2007

On Sun, Mar 18, 2007 at 09:57:51PM +0100, Krzysztof Halasa wrote:
> "Ahmad M. Hisham" <ahmadmhisham at> writes:

> > I have an output SVideo and TV input is composite so i use a converter.
> > Everything is OK at the laptop but on the TV the screen is BW image.

> This is normal :-(
> S-Video is two signals: chroma (color info) and luminance (B&W image).
> Your "converter" (which converts only physical plug shape) takes only
> luminance and completely ignores chrominance.

Depends on the converter: There are also converters which couple 
the chrominance signal to the luminance signal with a capacity and 
produce a perfect composite signal.

There are many reasons for getting no color: Broken cable, broken
converter, broken color carrier generation in the encoder chip
(some Chrontels do that), wrong assignment of signals to pins.

Possible fixes on the software side can include reprogramming the
signal assignments of the encoder chip (composite instead of
luminance), or in some cases changing the color carrier frequency to a
"wrong" value which nevertheless works. Assuming that the encoder
chip is known well enough to be actually able to reprogram it.

Without more details, it's hard to pinpoint the reason.

- Dirk

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