S-Video & Digital Audio from Dell?

I have a Dell Precision M90 with the usual 7-pin S-Video combo out
connector. I bought the "dongle" to split the 7-pin into 4-pin
S-Video, composite video and digital audio. I have a couple questions
/ observations I thought share / ask:

1. The digital audio out does not provide Digital Dolby output (i.e.,
receiver does not interpret input as digital and instead uses Dolby
Prologic II). This really sucks as it was the main reason for me to
purchase the dongle. Is my sound card not providing proper digital
audio to the 7-pin connector?

2. A standard 4-pin S-Video cable plugged into the back of the laptop
does transmit S-Video to the TV just fine - seems to be some confusion
with this. I'd guess the extra pins are for the composite video signal
and the digital audio and the 4-pin S-Video just doesn't use these
pins? If you don't need composite or digital audio, don't waste your
money on the dongle!

3. I experienced some flakieness using the dongle in certain
configurations. When using the 4-pin S-Video output from the dongle to
a TV it produced only B&W. Granted, I'm actually going to a box that
converts S-Video to coaxil for an old TV that doesn't have any inputs
other than coaxil. However, I have an S-Video to Composite adapter and
using the Composite Video in (still using S-Video out from the dongle)
fixed the color issue. The composite output from the dongle gave
colour. However, video quality using all dongle configurations weren't
as good (fuzzy noise around edge of screen) as simply using 4-pin
S-Video cable direct from the back of the laptop (but then of course
you don't get access to the digital audio, which for me, provides the
same audio quality as the headphone jack, so...). I'm surprised by
this as I figured the dongle would have been a more of less straight
pass through for the 4-pins for S-Video...

4. Maybe some of the problems above with respect to quality of image
were related to quality of cables? I'm mostly playing around with
different configurations and all cables are 3 or 6 feet in length, but
maybe the fuzzieness/noise was cable issues?

Specs:
M90, 2.0 GHz, 2GB RAM, XP SP2
NEC DVD ND-6650A
NVIDIA Quadro FX 1500M 256MB
Sigma Tel 65535 5.10.0.4943

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>I have a Dell Precision M90 with the usual 7-pin S-Video combo out
> connector. I bought the "dongle" to split the 7-pin into 4-pin
> S-Video, composite video and digital audio. I have a couple questions
> / observations I thought share / ask:
>
> 1. The digital audio out does not provide Digital Dolby output (i.e.,
> receiver does not interpret input as digital and instead uses Dolby
> Prologic II). This really sucks as it was the main reason for me to
> purchase the dongle. Is my sound card not providing proper digital
> audio to the 7-pin connector?
>

If the digital output is able provide the raw digital signal (Dolby 5.1 or
DTS), there will be a setting to adjust in the sound card properties
somewhere. This is necessary because the raw signal has the ability to
cause damage to equipment designed only for PCM signals. These outputs
usually provide PCM 2.0 or Dolby 2.0 (inc. Dolby PL) by default.

> 2. A standard 4-pin S-Video cable plugged into the back of the laptop
> does transmit S-Video to the TV just fine - seems to be some confusion
> with this. I'd guess the extra pins are for the composite video signal
> and the digital audio and the 4-pin S-Video just doesn't use these
> pins? If you don't need composite or digital audio, don't waste your
> money on the dongle!
>

Correct.

> 3. I experienced some flakieness using the dongle in certain
> configurations. When using the 4-pin S-Video output from the dongle to
> a TV it produced only B&W. Granted, I'm actually going to a box that
> converts S-Video to coaxil for an old TV that doesn't have any inputs
> other than coaxil. However, I have an S-Video to Composite adapter and
> using the Composite Video in (still using S-Video out from the dongle)
> fixed the color issue. The composite output from the dongle gave
> colour. However, video quality using all dongle configurations weren't
> as good (fuzzy noise around edge of screen) as simply using 4-pin
> S-Video cable direct from the back of the laptop (but then of course
> you don't get access to the digital audio, which for me, provides the
> same audio quality as the headphone jack, so...). I'm surprised by
> this as I figured the dongle would have been a more of less straight
> pass through for the 4-pins for S-Video...
>

Some S-video to CVBS (the coax as you describe it) simply bridgethe two
channels together. Not all video cards are happy with this arrangement.
The correct type of converter for these cards is one containing filters to
keep the two channels separate from the point of view of the vieo card. It
is usually only possible to tell the difference from the description.

The TV usually has to be explicitly set up for S-video input otherwise it
ignores the colour channel (hence B&W picture).


> 4. Maybe some of the problems above with respect to quality of image
> were related to quality of cables? I'm mostly playing around with
> different configurations and all cables are 3 or 6 feet in length, but
> maybe the fuzzieness/noise was cable issues?
>
> Specs:
> M90, 2.0 GHz, 2GB RAM, XP SP2
> NEC DVD ND-6650A
> NVIDIA Quadro FX 1500M 256MB
> Sigma Tel 65535 5.10.0.4943
>