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12-01-2017, 12:51 AM
jwillis84 jwillis84 is offline
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Random thought here.

The Property pages in the Vid Proc and other locations in the DirectX ksproxy sheets displays the AGC control but its always greyed out or unchangeable.

There is something that appears in 'plain sight' that might explain the AGC problem better.. and suggests a solution.. or workarounds.

Coencident with these models and the years of release.. the AGC problems also seemed to plague the newer cards when they started offering (new) premium models.

Right up until just "after" the Walmart "special" 9200 series the problem didn't seem to exist.

After that they changed strategies and offered [three] models for each, call them X, XT, PRO

Specifically this was the 9600 model when vague musings in threads started mentioning "Herringbone" interference. One person on another board noticed RF Choke coils appeared on the NTSC versions, but not the PAL versions of the 9600 cards.. and ATI started adding FM radio tuners (vastly lower frequency than video tuners) and Active cooling fans for the hotter running gamer chipsets.

Put simply their strategy changed to keep up with Gaming video card competitors and added a whole other FM radio circuit to the "premium" cards not available on the "basic" card version. These are definitely potential sources of low freqency interference when compared to video signal speeds. The brushes or sleeves in cheap GPU fans can randomly spark and "flash" EMP right next to or (if the chip is on the backside) directly over the capture chip.

I suspect the lower cost, less premium, passively cooled (no Fan RF) and no FM radio newer cards had less AGC issues.

The more stable simpler USB capture devices while not having all those potential problems also had to contend with poor cables and noisy or poor quality USB power and USB port connectors.. but AGC problems are rarely mentioned.

I don't know how to add shielding to these cards, but the AIW HD cards started appearing with gold and silver faraday cages over their tuners (to keep something out? or to keep something in?). One person actually desoldered and moved his choke coils on an AIW 9600 and had success removing RF interference from his video capture.

Suggestions:

1. stay with AIW 9200 or less capture cards (probably best, but hard to do)
2. avoid premium AIW 9600 or above cards or get the ones with no FM and no Active cooling fans
3. consider ways of shielding or spacing the capture card in the case to stay away from RF sources

4. if no other choice, then consider an external USB capture card, with a short, good dedicated (no USB hub) cable to the computer, and place the mains adapter as far from the device as possible.. and keep it away from the computer case fans (a Faraday cage for the USB device might not be a bad idea either).

I'm also noticing PAL cards seem to be better designed with spacing components and shielding in mind, better than the NTSC versions.. could be the nature of the PAL tuner generates more concern for RF interference and they had to take this into account earlier and that propagated forward into later designs. -- so if it doesn't matter, NTSC tuner or PAL tuner.. the PAL tuner cards (might) be better at rejecting RF interference.

I am not saying Macrovision [pulsing] will go away.. that is a different issue, and an external signal regenerator like a TBC can fix that problem (but probably not the one or two line TBC inside a VCR.. they weren't supposed to defeat Macrovision anyway).

.. just a random thought
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  #2  
12-01-2017, 04:28 AM
sanlyn sanlyn is offline
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Why is it that millions of people never had these problems with AIW cards?
Just my own random thought about my two AIW AGP's, circa 2001 and 2004, which I've used for capture instead of as competition for external multimedia systems.

Last edited by sanlyn; 12-01-2017 at 04:44 AM.
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  #3  
12-01-2017, 04:47 AM
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lordsmurf lordsmurf is online now
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jwillis is mostly astute in his observations.

I'd question whether "millions" had no trouble with AIW cards, at least in terms of actually using it for quality capture.
- Many never used the AIW side at all, mostly getting the cards for gaming. (And yes, I realize non-AIW existed, but the mentality of gamer nerds is often "I must have the best beefiest everything card". That meant poo-poo on lowly Radeon, hooray for AIW -- even if never used. I don't get that either.)
- Many more simply used to AIW for off-air recording in the pre-DTV era, often using the terrible defaults.
- Many never came here, and simply assumed "homemade video must look bad".

I use ATI MMC all the time for MPEG. From 2001-2006, always DVD-spec MPEG (DVD recorders from 2006 onward). From about 2012 to now, 15mbit MPEG.

I used ATI MMC for AVI many times pre-2009, because VirtualDub wasn't that great in the 2000s. The only issue with it is that, on some systems, it caused sync issues (and not from dropped frames). I didn't do much AVI at all before the late 2000s, due to size. Remember, a 100gb IDE hard drive was "big" (and expensive) in 2001, and 35gb/hour was painful to work with.

But I'm not in sync with jwillis conclusions...

Namely in NOT using the 9600/9800 AGP cards, nor in dumping AIW altogether for USB. That's taking it too far. The cards do work more than not, so don't assume you'll have issues before even trying.

And AGC wasn't an issue on AIW. No idea where that's coming from.

- Did my advice help you? Then become a Premium Member and support this site.
- For sale in the marketplace: TBCs, workflows, capture cards, VCRs
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  #4  
12-14-2017, 09:53 AM
jwillis84 jwillis84 is offline
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Thank you for the Input.

I am considering it and trying to take it into account as sage wise advice based on experience. That's of more value than second hand inexperienced opinion.

I am in the middle of slowly selecting components for two boxes (7500 VE - AIW) and (9600 - AIW).

I was leaning towards the later cards, but wound up down a meditation on the years when the motherboards I have available, the operating system versions, and service pack versions were available meshed with when the exact dates these cards became available to the public on store shelves.

Though driver sets and application suites could update later, the cards I have are still shrinkwrapped and complete, so their included CD roms will have the "starting" versions.. which reason would suggest would be best tested with what was available shortly before their release.

I noticed "patterns" and these were more interesting than AGC vs Feature creep and redesign speculations.

Fortunately the 7500 VE is PCI 1.0 and 9600 is AGP 8x and the motherboards are both Intel D865GBF so it should make for a couple of interesting observation experiments.

My lingering choices (after power supply) were confined to Sound Card for audio capture.. which I finally found what I think is good reasoning for selecting the Turtle Beach Santa Cruz above all others.
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  #5  
12-14-2017, 11:52 AM
NJRoadfan NJRoadfan is offline
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FM Radio reception shouldn't be an issue with card interference (it lays within the VHF TV band between channel 5 and 6). The shielding on the tuners was to prevent interference from the inside of the computer from affecting analog TV and radio reception, not the other way around. Any difference in tuner size was due to ATI experimenting with newer "digital" tuning tech that later on didn't prove too reliable.

For the TL;DR crowd, ignore the tuner, its a non-issue with regards to capture.

Any analog video and audio source is going to have problems with interference inside of a computer as its an inherently noisy place. Proper shielding and power filtering solves a good number of those problems. I wouldn't be surprised it many of the noise problems are from defective components that aren't filtering anymore (caps, chokes) or spewing out noise that they shouldn't (just about anything). The best solution for analog to digital capture is usually external devices as they can be easily shielded/isolated from the host machine.
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