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27th February 2006, 03:58 | #1 | Link |
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New Technique: Component4All!!
Yet another ground-breaking cap technique: now anyone can capture pure component video with no special equipment! Forget expensive pro-level cards, you don't need 'em!
Updated 03-2006: This technique increases your potential resolution by about 2x beyond what you could do with lossless HuffyUV. So the real resolution is 1440x480, yes that's high-def! To keep this amazing resolution you will have to save in hi-def, otherwise, you will lose - for example saving as Huffyuv will use YUY2 color format - this means 2 pixels of color are stored as one. Caveats: - your source must be 4:4:4 ** UPDATE: this technique always improves quality, because svideo has inherently low color resolution, even if your source was only YUY2 orignally. You can get all the 4:4:4 quality as well if the source uses real chroma or 4:4:4 chroma upsampling. - you will have to cap 3 times in a row, in a repeatable way - it's slow - the cheap and fast version, has slightly wrong colors - you have to really want some hi-def glory... Ok, now here's how: you need a "Y" splitter cable, two females to one male, type cinch/RCA/phono. You need an svideo to composite connector, or just a composite connector on your cap-card. DISCLAIMER: This technique requires you to make non-standard connections. The risk is your own. Connect Y directly to your composite in. Cap. Connect Y and Pb together, send to your composite in. Cap. Connect Y and Pr together. Cap. Make 3 files: y.avs, ypb.avs, ypr.avs. Put your mpeg2source and trim commands in here, so that all files start playing from the same frame. Final step: run this script. Code:
y=avisource("C:\MyVideos\y.avs") ypb=avisource("C:\MyVideos\ypb.avs") ypr=avisource("C:\MyVideos\ypr.avs") vyu=mergergb(ypr,y,ypb) return(vyu) Results: -The grey range, and flesh colors are excellent. Some rare colors are shifted, but you cannot notice this. In theory it's "wrong", but it works. -The color fringes around strong colors are gone! (something I find very annoying about s-video). -If you dropped any frames in any caps, you will start to see some ugly color ghosting. - UPDATE: I now have a script which exactly recreates the RGB picture, colorbar test patterns are accurate. However this requires some careful, one-time calibration. I'm working on the calibration proceedure. - UPDATE: I have test results which prove >=1.6 color resolution as measured from a DVD Video Essentials test DVD pattern - chroma frequency sweep. I have many more ideas brewing - stay tuned. (>2 times further resolution is possible...) Last edited by jmac698; 7th March 2006 at 22:19. Reason: disclaimer |
27th February 2006, 07:12 | #2 | Link | |
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Expain to me how capturing and layering the multiple color planes is going to give me "HiDef" 1440x960 out of my trusty AIW capture card which is only capable of 720x480??? All you are getting out of this is "possibly" a better color depth in the final capture. T |
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27th February 2006, 16:33 | #3 | Link |
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resolution controversy
I was waiting for someone to say that
Yes, of course it's debatable, but let me explain my reasoning. If your card caps in CCIR656 format, that's 4:2:0 or 4 pixels/luma, your resolution is 720x480 Y, 360x240 U/V. If we call this "720x480 resolution", then any increase must be spoken in different terms. My technique caps 720x480 Y, 720x480 U/V. You cannot store that resolution in a mpeg2 without loss. The only way to keep this true color resolution is with 4x larger mpg file. Or if you prefer, call it true 720x480, because usual 720x480 was never true. But be sure to call DVD quality not true 720x480 either. Besides this debate, is the reality. I've tried it, and it does look better to me, even a test DVD with frequency tests shows better U/V response. And it's a hidef source sent at 4:4:4 (apparently). That just shows you - it takes a hi-def mpg2, downsampled, to make true 4:4:4 color. What if I said I could also cap 480P? Is that an increase either? There are also theories of perceptual resolution. Usually the saying goes, we can't see colors in hires. So how come I can see fringes of colors in s-video? It's too low color rez vs luma rez. |
27th February 2006, 17:55 | #5 | Link | |
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I don't know what card or the source you are using, but both my AIW and my CX2881 based cards can both capture in YUY2 (4:2:2) format. I have never noticed any color fringing as you describe (primarily LD and OTA caps) using either card - I NEVER cap using any MPEG codec... I capture to AVI using HuffYUV. As to your capture problem, it could be one of two things (as it always is with analog capture) your source device or your capture device. Your source could be smearing the chroma information, i.e. poorly designed or defective electronics, or your card is garbage, i.e. poorly designed or defective electronics. It does not take much of a phase delay (common in poorly designed electronics) to introduce artifacts in the chroma vs luma overlay. Cables with too much cross talk/leakage can also cause similar problems. I think it would behoove you to read up on luma and color as used in the current video standards (NTSC or PAL) and see the relationship between them - more is not always better Improved bit depth (4:4:4 vs 4:2:2 vs 4:2:0) only delivers greater color accuracy, not detail. The idea of using multiple captures to improve the final results is not a new idea - search the Avisynth forum for a filter called TooT and its derivatives. They perform a pixel by pixel averaging accross three caps and toss any outliers producing signifiantly reduced random noise in the final capture - the do nothing to improve the resolution of the end result. T |
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27th February 2006, 20:06 | #6 | Link | ||
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debating...
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Regardless, my technique causes a 2x improvement in that case, using AVI formats and a YUY2 card. I am aware of the multiple cap technique, I read the original post a long time ago. This is not the same at all, obviously, but I could make use of it to fix small off-by-one errors in Y between my caps. S-video fringing: have to explain this better, so we both know what we're talking about. Here's two examples: the beginning of Blade Runner, with the red word "Replicant", certainly stesses color resolution. From DVD to TV in svideo, also from Hollywood Plus to TV, I see smearing of the red, as a gradient, fading towards the right, for about a few pixels. It also shows up in OTA caps. You have to know what to look for, it's generally not a big problem, just when two pure colors are contrasted together. Look yourself, for a blue object on a white background, and see if there's any blue that leaked into the white. I looked at my technique in both U and V planes with VToY(). I can read lettering in my "C4All" technique, but I can't in the U/V of Svideo cap. Svideo uses a color carrier of 4.43/3.57MHz. It can't possibly have higher frequency content, because it is amplitude/phase modulated. Luma has a 13.5MHz rate or so, if you do 720*1/53.3uS. So recording full bandwidth color from the luma input pin certainly makes sense. Quote:
4:4:4 Y'CbCr Y'0Y'1 Y'2Y'3 CbCb CbCb CrCr CrCr 4:2:2 __Y'0Y'1 __Y'2Y'3 Cb__ Cb__ Cr__ Cr__ 4:4:4, 24bits/pixel. 4:2:2, 16bits/pixel. 4:2:0, 12bits/pixel. There is 8bits to store Y/Cb/Cr, but eg. 12 bytes to store the 4 pixels of 4:4:4, averaging 24 bits/pixel. I think you may be confused when they say 4:2:2 has more bits/pixel than 4:2:0, yes that's true, but it's only because every other pixel of Cb/Cr is taken, and they average to 16bits/pixel. Really, each value is still stored in the same color depth, 8 bits of Y/Cb/Cr. It also shows that the color comes from different pixels than the Y ones! So the color is inherently offset by 1 pixel left. That would explain the color shift problem, which is corrected by the vhs filter, or the option in dscaler. If it were rgb 12 bit graphics, it would only have 4096 colors, 4 bits per value, and look obviously much worse Last edited by jmac698; 27th February 2006 at 20:30. Reason: speling :) |
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27th February 2006, 21:54 | #7 | Link | |
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And BTW, what source would you have that is outputing in component and yet is not already in a digital format and why would you want to capture this through an analog pipe? If it is off of a PVR or a DVD, either grab the .ts file or rip it - will certainly be faster and better results. T |
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27th February 2006, 22:35 | #8 | Link |
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@jmac698,
You might want to read http://www.doom9.org/index.html?/cap...roduction.html http://www.doom9.org/index.html?/cap...gue_video.html |
27th February 2006, 23:20 | #9 | Link | ||
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bandwidth
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This makes your final sample rate 704 samples / 52 µs = 13.54 MHz. This is sample rate. According to the Nyquist theorem, you can record frequencies of half the sample rate, making the bandwidth 6.77MHz. Modern video DAC's have excellent filters and I expect to reach very near this value. If you read my post, I said rate, so while I was correct, I should have compared bandwidth MHz numbers together, I apologize for the mistake. In any case, the luma bandwidth is still greater, in one estimation (approx.), 6.77/3.57=1.88 times better. Quote:
Anyhow, the technique is there for those who want to make use of it, as is the multiple cap technique to reduce noise. Judging from the forums, many of us are interested in ways of improving quality. |
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28th February 2006, 03:32 | #10 | Link | |
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Also do not forget that all cards on the market have some intended and unintended filtering happening in the analog domain before it ever reaches the ADC (not a DAC BTW). Since MFG's typically use a simple, ie inexpensive, 3db or 6db filter prior to the ADC, the cut-off frequency will be significantly lower than Nyquist such that the rolled off frequencies will be reduced below the ADC's sensitivity @ Nyquist. I would be willing to bet that your card is limiting the analog to something less than 4.5MHz, so no matter what you do RE sampling, you are never going to get better than that. Since it sounds like you have a PVR (I assume since you mention a three pass capture), why not hack the box or remove the HD to get access to the files? Peace, T |
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28th February 2006, 07:26 | #11 | Link | |
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It would be best to use a one transistor emitter follower for each source before inputing to the capture card. Many times the chroma channel out is of high impedance compared to the ~ 50 ohm impedance of the "Y" out. This does in some cases causes color smear or phase shift. I am still interested in your idea. Richard |
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1st March 2006, 01:20 | #12 | Link | |||
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rfmmars:
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tedkunich: From the Connexant 878a datasheet: Quote:
I have no doubt that what you were saying is valid for purely analog circuits, but digital oversampling filters can be almost perfect right to the edge of operation. There is also a "sharpness' register in the chip to let even higher frequencies through. Read a review of the Creative X-Fi soundcard, you will see +-.1dB all the way to Nyquist. As for your other question, please see the thread in general discussion. |
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1st March 2006, 21:56 | #13 | Link | ||
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Oh, BTW, the sharpness register on the BT chip sets only boosts gain of the higher frequencies by changing the taps in the bandpass filter - is does not change the cutoff, just the shape of the rolloff (think peaking just before rolloff) T |
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2nd March 2006, 17:03 | #14 | Link | ||||
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impedance, oversampling
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Anyhow, did you look at my tests? I don't think cables cause my smearing problem. I'll have to take a picture to show you, and see if you can't replicate it. I'm starting to think now that the svideo itself is mostly the problem, and maybe my outputs aren't 4:4:4 afterall, but it doesn't matter as there's a significant beneift to avoiding svideo anyhow. Last edited by jmac698; 2nd March 2006 at 17:21. |
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2nd March 2006, 17:27 | #15 | Link | |
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T |
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2nd March 2006, 22:25 | #17 | Link |
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samples
Hmm, you need to see, side by side, obvious difference comparison.
Technical measurements: still useful, however. Note the 6 bars at the top, these are MHz markers. If colors under bar4, it means the frequency is 4MHz. The svideo stopped before bar4, while the C4All continued to the very edge, which is 6MHz. I'll make labels. For the b/w pictures, it's the same thing, but showing the direct color plane (U/Cb,Pb). This is pure color info translated to b/w. It's a little easier to see. How was it generated? Don't know, it's from a reference test disc, have faith Smearing: not here. Example coming. New tests coming. My technical tests showed, 1) no freq. response difference btw svideo cables 2) svideo color response to 3.75MHz 3) C4All response off the scale, at least 6MHz. Last edited by jmac698; 2nd March 2006 at 22:35. |
3rd March 2006, 00:04 | #18 | Link | |
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It would be interesting to see the schematic of the DVD player you are using. I wonder what type of filtering may be happening in the SVideo output circuit inside the player itself. I know that I was able to resolve 5.5MHz out of my Pioneer DVL-919 deck with my Winfast card (CX23881 based) using S-Video doing my LD captures. T |
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3rd March 2006, 00:18 | #19 | Link | ||
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svideo response
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This is very interesting, some kind of professional outboard adc/dac http://www.aja.com/iofamilyspecs.html Quote:
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3rd March 2006, 01:45 | #20 | Link | |
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You can see that the NTSC standard does not carry much high frequency information in the chroma. Check out this site for more info if you are so inclined... http://www.ntsc-tv.com The layout is really goofy but there is some good information in there. T |
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