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G400 Full Screen cap - interlaced??

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  • G400 Full Screen cap - interlaced??

    I've had a lot of trouble getting the full-screen capture to work properly on my G400 Marvel. Half-screen works fine, but with full screen most of the time it just produces this unplayable output with like horizontal lines messing it up, I am not sure if it is some kind of interlacing/syncing problem or what. I had it working before, but I'm not sure how, I went and started downloading all different versions of video tools, drivers, and MJPEG codecs and worked at it for like 2 days and finally got it working somehow. But now it doesn't. I have the "latest and final" driver and video tools (6.28, 1.55). I may try some more things but I am not hopeful. Any advice??

  • #2
    If I'm not misstaken, above 352x288 video capture is interlaced, you have to deinterlace(virtualdub) it if you plan to make the final video on divx or other avi format; if you plan to make mpeg, keep the file interlaced. Just a curiosity: Are you capturing with which OS?
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    • #3
      Make sure that if you plan to view on a computer screen, you have it frame based. If you plan to view on a TV, through any means, the Marvel requires you to choose Field B. If you make it Field A first, it'll look awful. However, just to complicate the issue, some softwares bugger you really up and swap Fields A & B (which may be named 1 & 2, upper and lower or a whole host of ambiguous, confusing and arbitrary terms). How are you capturing and with what software?
      Brian (the devil incarnate)

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      • #4
        OS: Win98FE
        Capture program: Video Tools 1.55.043
        Playback program: Usually Activemovie. It's the only free one I've ever seen with good frame-by-frame seeking, start/stop marking/looping and ease of use.

        Brian: Can you explain more about these fields A and B? Where on earth would you select something like that. I don't understand why decisions like that wouldn't be made automatically and correctly by the capping and playback progs.

        areia: You say all full screen video is interlaced?? I thought that was just done in situations like adding junk frames for NTSC conversion, etc. Is this one of the advantages of DVD over VHS?

        Now, I could have sworn that previously I was able to fix this problem after about 2 days of codec deleting/reinstalling. Is there some better MJPEG codec I should be using? All I see in there right now for MJPEG is "Pvmjpg20 [MJPG]" which doesn't seem right.

        I'm attaching a picture of an example of the interlacing that is happening on my full screen capture. Tried it in both activemovie and media player 6.4, same result.
        Attached Files

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        • #5
          the screen capture looks perfectly allright to me... exactly what it should look like.

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          • #6
            Yep, even down to the black stripe at the top and down the left hand side! Known problem that is nothing to worry about. See one of my posts a few months ago.

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            • #7
              dZeus: you DID notice the massive interlacing right? This is in
              practically every frame.

              DarrenD: Well upon your suggestion I scanned for all of your posts, and all I found was talk about black areas on the edges. That was never my question, it was the interlacing of frames. Unless there's some post I am missing...

              So, forgive my ignorance, but anyone want to explain this interlacing thing to me? I know that TV's are interlaced, but they are running at _60_ Hz. (NTSC) So the 30 frames coming per second are interlaced normally in that way. But I am capping at 30 FPS. There's no way you are gonna tell me that at 30FPS the source video actually looks like this, i.e. every frame of the 30FPS is just an interlaced mess. I am assuming what is happening is the video cap card is getting half of one "60 Hz" frame and half of the next, and wrongly combining those 2 perfectly normal interlaced frames together to form the unholy monstrosity you see before you. This actually makes a lot of sense now that I've thought it through.

              So basically the Matrox card has no clue when to start capping the interlaced half-frames, and keeps doing it wrong time and time again. I guess what you have to do is what -- run the whole thing through a filter to tear apart each frame, shift them all ahead half a frame, and put them back together how they should have been in the first place. Wonderful. That's of course assuming the Matrox card is even being CONSISTENT in its wrongly interlaced frame-merging. I shudder to think of the possibility of dropped HALF-frames and it going in and out of sync such that you'd have to "fix" segments at a time.

              I also suppose the frames that look "normal" and non-interlaced, came out that way because those are junk-frames added in to conform to 30FPS? Thus the wrong-interlacing isn't noticed at those points since it's the same frame twice in a row. Just a guess.

              I guess the G400 Marvel is really just a "toy" cap card after all. Motivation to get something better with my next machine I suppose. That and the fact that Matrox refuses to release comprehensive G400 drivers for the newer OS's. I'll probably be looking elsewhere for my future capping needs... bout the only good thing about Matrox is this helpful forum.

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              • #8
                Hmm nevermind. I read about interlacing. Man, this is stupid. So there's no easy fix like I dreamed up. I assume (there I go again) that HDTV is not interlaced? If this isn't a good reason to junk old TV technology, I don't know what is.

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                • #9
                  I see what Turbo's on about. I noticed the same thing when I would try to render certain full-screen captures to SVCD. Gave up on that when I got the DVD-R. Never did figure out how to minimize the problem except to be careful what mpeg resolution I used for what capture format in rendering.

                  VideoTools should automatically capture field 2 (Field B, lower field, what have you) no matter whether it's full or half or 1/4 screen. In Premiere you set capture to "lower field first." not sure about MSP or the others.

                  How does it look when you view it on a regular TV using video-out?

                  Kevin

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                  • #10
                    You will have to deinterlace in order to get a good picture on a computer monitor.
                    VirtualDub has some nice filters for this.

                    If you intend to view on a TV set or a composite monitor then have the "Use Field-Based Scaling" set to on, in the DualHead DVDMax Options.

                    Regards,
                    Debbie

                    PS.

                    Have a look here!!
                    Last edited by Debbie; 28 January 2003, 23:44.
                    We pass this way only once. Make the most of it !

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                    • #11
                      As I said earlier, if you want it on a computer screen, deinterlace. The image you show will look perfect on a TV set.

                      "I guess the G400 Marvel is really just a "toy" cap card after all."

                      This ain't so. I used a Marvel for many years and it gave excellent results with my camcorder output. Its quality, using the native MJPEG hardware codec, was better than any TV set. At the time, my o/p was mainly on tape although I did progress to SVCD, very successfully, before I scrapped it.

                      To take your example, it is obvious that the camera was panning heavily when you shot this. You have two fields, taken 1/60 seconds apart, on the one frame. Of course, you will get this effect. Notice that the "tearing" is less on the skater than on the background. This is because the relative movement of her, to the camera, was smaller, because of the panning. This is a fact of life that you cannot avoid with standard TV. As I said, if you play it back on a TV, it will look normal, because the two fields will play successively at 1/60 sec interval (assuming they are in the right field order) and not superimposed, as you have in this still.

                      You may ask, why interlace at all? This is a question of bandwidth. If you had non-interlaced 25 or 30 fps TV, the flicker would be objectionable or the phosphors would have to have longer persistence, causing image smearing. If you had 50 or 60 fps non-interlaced, the luminance video RF bandwidth would need to be 12 to 16 MHz, instead of 6 to 8 MHz. This would result in fewer stations per band, more sideband interference between stations, poorer RF sensitivity of the receivers (hence range) and a halving of the signal to noise ratio. This would also have severe economic repercussions on the cost of TV receivers and on programming (shorter transmitter range = fewer viewers = less advertising revenue for higher cost hardware). In fact, very few viewers would even notice the difference between an interlaced and non-interlaced image, so interlacing has everything going for it. In fact, of the 12 internationally recognised CCIR standards for TV signals, guess how many have 2/1 interlacing? That's right, 12. This is about the one and only thing that ALL the standards agree upon.
                      Brian (the devil incarnate)

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                      • #12
                        TurboCMinus:
                        Agreed, the black lines were not part of your question. However, I thought once you got over the interlacing that would be your next question. It was for me when I started down this journey of video editing.

                        What I found useful in testing the interlacing and field order was to capture 30 seconds of my kids (Hi-8 camcorder) and then go through all combinations of field A and B in my video editor and MPEG-2 encoder. I labelled each as FieldAProjectFieldBEncode.mpg and so on. I then built a DVD (yay DVD Burner for Christmas) and played all combinations on my DVD player linked to the TV. I then noticed which one was the correct one.

                        I have yet to do this with capturing TV pictures (via the TV tuner not S-Video as in camcorder). Someone told me TV pictures may be different field order and interlaced. However, there is nothing like trying each combination on your own setup.

                        I hope this clarifies things and helps.
                        P.S. To the gurus out there please correct me if I am wrong as I am still learning this stuff.

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                        • #13
                          Well, even ignoring this unavoidable effect, my "toy" comment was also brought on because the captured video from my Matrox has always looked a bit "washed out." Recently I've been looking back into reinstalling some color-control software to try to fix this. My previous video card came with Colorific. I just tried installing it again, with this card, but it doesn't seem to like it. I calibrate it, and it goes through all the steps, then afterward it still tells me it isn't calibrated. :P Maybe it's locked to only work with the old card (Graphics Blaster Riva TNT 16M AGP), I don't know. If anyone knows of some good free color-control software to use with my Matrox G400, I'd like to know.

                          As for the interlacing, I read your links and others, still seems very problematic. Especially for someone like me with a Celeron 400 processor. Seems like the absolute best method would be to halve the vertical res while stretching it vertically and doubling the framerate. So you don't lose any video information and also don't create stupid blurring effects. Unfortunately, I'm sure there's no way my processor can handle that. Maybe the best method for me is to just cap at half-vertical res and full horizontal-res. That avoids interlacing and also lets me increase the JPEG quality from where it is now. Er, no wait, that's not an option??? Pffttt... lame. I see 704x480 15 fps. If I cap at this setting, am I gonna receive 2 half frames in a row, then it will skip the next 2 half-frames in a row? Or will it give me every other half-frame? Sigh. Why can't things just be easy. :P

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                          • #14
                            I hear you about the VT-captured video looking washed out. Here are the settings I use:

                            Brightness 48
                            Contrast 51
                            Hue 51
                            Saturation 84

                            Output settings (from the PowerDesk readme):

                            Brightness 180
                            Contrast 234
                            Saturation 137
                            Hue 0

                            Gives decent color quality and sharpness. You might have to tweak the numbers for your purposes.

                            Kevin

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                            • #15
                              I'll try those color/brightness/etc settings, but one thing I notice is, if I take a normal scene, say with some people or something, I can increase things like saturation and make it look nicer. But, then I'll go and look at something like figure skating, and that will look HORRENDOUS, the ice will just be a massive blur of white. So I'll just have to revert back to standard settings. Maybe the "washed out" standard condition is the best you/they could do to make it work properly with all types of input.

                              I mean, I'm very happy with the card, especially since I got it brand new for $99 on ebay. It's perfect for this machine. But whenever I manage to get money together for a new machine (4 years and counting...) I'm looking forward to getting a really nice quality capture device to go with it.

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