Resolution and Interlacing ??

[Tiffany]

Having read conflicting reports on exactly what resolution to capture, I connected my Sony digital camera to my mjpeg capture card which fed in composite video of a single image (just as you can connect the camera to the video-in on the tv set and view the pics). I wanted a still image so that I could closely compare a capture at 352x288 (pal) and than see what I was missing by then doing a capture at 704x576. I compared the two captures side by side and could see only a very slight bee's dick of a difference in the full-size capture. The quality of both AVI's were excellent, and I have no problem with taking the 352x288 AVI and converting it into Mpeg2 with TMPGenc.

Capturing in higher resolutions introduces the magic of Interlace, and again I have read varying comments on whether to de-interlace, etc. So setting up TMPGenc so that it would read the 352x288 AVI I encoded two complete 50 minute Mpeg2s from an AVI which I had captured from Sat TV. Again, excellent quality AVI (even at 352x288). One was encoded by TMPGenc as Progressive IN and Progressive OUT. The next (using the same AVI) was encoded with Progressive IN and Interlace OUT.

Knowing that a computer monitor is always non-interlaced, I gathered some folk around our Loewe 100hz TV set and we sat down with pizzas and coke and compared the two SVCDs. The general feeling was that one was no better than the other, and infact the Interlaced vid was not as sharp. Noone except me knew which was the Interlaced, and which was not........

.....Comments and/or suggestions ?

Hardware
Athlon 1800 on Asus mobo
Capture Card Matrox Marvel G200 Mjpeg
Win XP
Tmpgenc and CCE

[bb]

Did I get you right that you captured digital sat TV through analogue video in of your camcorder, which converts it to DV, then you capture the DV signal to MJPEG through your capture card? In the end you encode to MPEG-2 to watch it If that's true, then you loose much quality along the conversion path:

1. digital -> analogue: lossy
2. analogue -> DV: lossy
3. DV -> MJPEG: lossy
4. MJPEG -> SVCD MPEG-2: lossy

Well, that's anything else but an ideal setup. I wouldn't be surprise if someone told me that you don't see much of a difference at the low-quality end, no matter what resolution you use.

By the way: Interlaced encoding will result in a smoother video, if - and only if - the source is interlaced, too. For SVCDs interlaced encoding is not recommended, because you are too limited in bitrate.

Using a proper setup you will definitely see a huge difference between properly encoded SVCDs from a 352x288 vs. 704x576 source.

bb

[Tiffany]

Sorry I may have confused you with the digital camera part. The camera is not a movie camera, just a digital stills camera. I used it to input a video still picture so I could compare a low res against a high res.

The way I capture is this...Composite video and stero audio cables run from the back of the Foxtel box (no DV output) into my Matrox G200 Marvel capture unit. It can capture uncompressed, or MJpeg. The AVI it captures is good quality. So I capture 352x288 MJpeg AVI and then put it through VDub to cut out the TV station breaks and maybe
add some filtering, then frameserve it to TMPGenc. The end result is an SVCD which needs close inspection to pick it from the orginal....

[Swan]

So I capture 352x288 MJpeg AV The end result is an SVCD which needs close inspection to pick it from the orginal....
Tiffany, just a tip: if you're making SVCDs, you should capture at 480 x 576. Or even better, capture in 704 or 720 x 576 and let TMPGEnc resize down to 480 x 576.

/Maria

[bb]

Originally posted by Tiffany
The end result is an SVCD which needs close inspection to pick it from the orginal.... How big is your TV set? Did you try to compare the video on a PC monitor?

My experience is that high res captures look much better than low res, and I guess I share this opinion with the rest of the forum members. So if your low res quality is close to your high res, then you're doing something wrong, probably with the high res part. I yet have to find out what...

By the way: the quality of 352x288 AVIs is never "excellent", just because of the low resolution. The HDTV people would probably call even 720x576 a crappy resolution. And all SVCDs are known to be of "ok" quality at best, but far from "perfect".

bb

[dar1us]

But do those HDTV people really STORE things at 1920x1080. You would need like 30 mins per XVID CD(700mb) to be able to make out anything.

Stick with SVCD for now. DVD if your budget will stretch, I would get into DVD-R... but if only drives were cheaper, DVD-Rs (4.7gb) are about 30p each (€50 cents? (bloody euro)).

TV's do a lot of combing and bluring AND sharpening. A PC will show what the source looks like, thats why VCDs COMPLETLY suck on PC and KINDA suck on a TV - but not sooo much.