DV AV Passthru / Analog to Digital Conversion questions...

[abm100]

I previously owned a Sony DCR-TRV240 Digital8 camcorder and replaced it with a Panasonic PV-GS120 MiniDV camcorder. I decided to redo an analog capture of a tape with the new camcorder for comparison purposes. The analog device is a Panasonic D406 VHS-C camcorder.

The DCR-TRV240 worked fine.

On the PV-GS120, I got artifacting and in fact I got artifacting with every tape. This lead me to experiment:

1) I used a regular tape in a VCR connected to the PV-GS120, and I got no artifacting.

2) I used a VHS-C adapter in the VCR and played the tape, but the output to the PV-GS120 only resulted in a blue screen. It played fine on a TV.

3) I used various cables to connect the D406 to the PV-GS120 and all artifacted. I have a Monster cable (expensive) and the D406 would not output video with it. The PV-GS120 works well with it.

4) I used the VCR as a go-between for the camcorders. (D406 plugged into the VCR inputs, the PV-GS120 connected to the VCR outputs). The PV-GS120 only displayed a blue screen, but it played fine on a TV.

5) I performed the same experiment on my DVD Recorder (RCA DRC8000N) as method 4). This worked. In fact it works really well. The colors are richer and match the original tape. On the direct connect to the DCR-TRV240 and PV-GS120 the images were essentially the same (excepting artifacting) - the colors were a little washed out.

Using method 5) I "passthru'ed" the tape using WinDV. It was configured for Type-2. In the preview screen for WinDV, all looked well, but upon playback, there were 5 small gray rectangles on the video. I used various tools to play back - Windows Media Player, PowerDVD, VirtualDub, etc. Whenever I capture a MiniDV tape in the PV-GS120 using Type-2, it looks fine. I changed WinDV to AVI Type-1 and recaptured. This time, the rectangles were gone.

Questions:

1) Why did the Monster cable have difficulty with the D406?

2) Why do I need to use the DVD Recorder to perform the passthru and why are the colors better?

3) Why do I get gray rectangles in Type-2 captures using method 5) when I don't get them with regular MiniDV tapes?

[trevlac]

#1 - Hard to say. The D406 may produce a very poor signal. Meaning the parts you don't see (that keep the picture in sync) are not to spec. The Monster Cable may be carrying this differently than the other cables and the Cam can not lock on to digitize the picture. TVs are extreamly forgiving.

#2 - How are you comparing? The colors on a TV and on a PC monitor look different. I'm not clear on your story, but if you produced DV and viewed it on a PC for all tests, then it might be that the RCA outputs a high chroma signal. Also it might be an analog setup issue. Meaning the D406 outputs a signal at IRE0 vs IRE7.5 and the RCA deals with it where the cams do not. I want to re-state that you have to look on a TV to make sure which is good. The RCA may be too chanked up.

#3 - I don't see how Type1 vs Type2 matter. They have to do with how the sound is stored in the file. Perhaps you should test to see if this is consistent behavior. Maybe on the 2nd try the cam got the signal better.


Your story was a bit in depth. I would be happy to talk about the color level issues #2, if you could restate your tests :
ie.. D406 (composite)->TRV vs VHS(svideo)->RCA(svideo)->TRV ect....

I would suggest simply record to DV(D8) and then play that back on a TV from your cam. This will cut out the pc viewing part. (Unfortunately, the analog out of your DV/D8 cams may be off, but you should be able to tell by comparing original DV footage out vs the VHS-C recorded footage.) I would also try an SVHS machine if you have one. It may do worse playing a VHS-C tape, but an s-video connection can improve even VHS.

PS: I recently did some tests comparing a D8, 2 DV cams, some capture cards, and a professional level DV capture device. One of the DV cams was a sony 3ccd prosumer cam. The DV device costs ~ $1700. I thought the D8 produced the best result. I posted this under Larid vs canopus in this forum.

[abm100]

Thanks for the response!

I noticed the color differences on the computer monitor and the PV-GS120's LCD screen. You make a good point about viewing it on a TV. I'll burn the results and do just that. I hope the color shift doesn't mean that the TV will look off or bad!

Later this evening, I'll redo some tests and post what I see.

The DVD Recorder has S-Video IN/OUT, but the D406 only provides the Mini AV (?) connector. I can perform S-Video OUT from the DVD Recorder to the PV-GS120 though.

Unfortunately, I don't have an S-VHS machine. I thought about that one.

[abm100]

I've performed a few tests (I had other issues this weekend), and I can report this:

On question 1), The Monster cable does work with the D406. I noticed a similiar problem with a different cable, and unplugging it and then plugging it back in solved the issue. Really weird, but I'm glad it works.

On question 2), The color is the same connecting camcorders directly and going through the DVD recorder. The difference is that the DVD recorder is somehow adjusting the signals to remove some of the grain. It looks better.

On question 3), I haven't gotten back to it. I removed my Panasonic DV codec this weekend and replaced it with a Sony DV codec. I'm not sure if this will affect my Type-2 captures, but having the Panasonic codec on my machine seemed to interfere with my ability to copy Type-2 AVI files back to tape. I'll test more in the next day or so.