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  #1  
07-15-2011, 05:32 AM
naripeddi naripeddi is offline
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All,

I know ADVC is not advisable for capturing from analog sources like VHS due to DV format's treatment of analog color.

I am trying to capture TV braodcasts from a Satellite box that has Component, Composite and S-Video connections. If I use S-Video option for capturing from Satellite box through ADVC-110, is it good enough? or will it still mess up with the colors as it converts Satellite signal to DV format? My Satellite box ha "High Quality MPEG4 compression" written on it.

I know a Canopus ADVC does DV only, and it does it using the hardware chip inside.

I also have a very old Pinnacle PCTV USB2 capture device, but it has only Mono audio connection. Also, I am not sure about the picture quality of that device when it comes to capturing Satellitebox. Link: http://www.amazon.com/gp/product/B00...SIN=B00028CAJ4

I am unable to find the ATI TV HD Pro card in my (PAL) part of the world.

Is Canopus good enough for capturing (analog) S-Video signal from Satellite box? or the same critism applies on ADVC in this scenario as well?

Also, is full DVD resolution appropriate or Half-D1 while burning to DVD from ADVC's output?

Thanks for the response.

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  #2  
07-15-2011, 11:46 AM
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Hi naripeddi, welcome to the site.

Quote:
I know ADVC is not advisable for capturing from analog sources like VHS due to DV format's treatment of analog color
Correct. It's really a video shooting format, not an ideal VHS videotape conversion format.

Quote:
If I use S-Video option for capturing from Satellite box through ADVC-110, is it good enough?
Quote:
I am unable to find the ATI TV HD Pro card in my (PAL) part of the world.
Yes, it is good enough.

And not that rubbish "good enough" (meaning it's bad, but somebody wants to ignore quality problems), but that it's actually going to be okay for what you're doing. You won't end up with a bad video from using the Canopus converter box. And s-video is going to look fine.

Why?

DV compression, or more specifically DV colorspace compression, is measured/annotated by a series of three numbers. For example, 4:1:1 (NTSC) or 4:2:0 (PAL), for DV. In the realm of colorspace, the earlier the number, the more important it is. In a preferred 4:2:2 colorspace, as an example, "4" is most important, followed by the first "2" and finally the last "2". Y is uncompressed (4), and UV (CrCb) is half ratio (2 each). For colorspace, 4:4:4 is uncompressed YUV.

Although theoretically good enough, 4:1:1's quartering of UV leads to color "cooking" and other problems. It varies between codecs (i.e. Canopus vs Canon vs Matrox), but it's there. DV 4:2:0 and DVD-Video 4:2:0 (two different methods of 4:2:0), are not really "0", but it's a way to express in the x:x:x number system how UV is "co-sited", or spread out more evenly than 4:1:1. In practice, 4:2:0 tends to look better than 4:1:1 when used as a conversion format. Again, much of this is to blame on the codecs, which seem to be optimized not for conversion but for shooting video.

I know the science of DV colorspace, and understand the theory that 4:1:1 is supposed to be great, etc etc. And for shooting video, it's true. For converting videos, it's obvious that there are visual issues. My eyes don't lie. Most documentation concerning colorspace and DV was written for shooting, not conversion. It's really the elephant in the room.

Quote:
Also, is full DVD resolution appropriate or Half-D1 while burning to DVD from ADVC's output?
Most recordable television sources are closer to Half D1 352x480 than full-sized 720x480 Full D1. And you can fit up to 3 hours on a single disc in high quality. In fact, 3 hours of Half D1 looks better visually than 2 hours at Full D1 -- it's closer to 1 hour of 720x480 quality.

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  #3  
07-15-2011, 11:55 AM
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Here's a great example of colorspace compression, from a Wikipedia image from the chroma subsampling article.


800px-Colorcomp.jpg

Look at the gold and red dots on the train door.

Note the garbling of edge detail in 4:1:1, due to the quartering of chroma information. This affects clarity of image, as well as "cooks" the color quality. It leads to issues of creating a blocky "digital look" against the other colorspace options.

Most likely this was a conversion comparison, since it shows the same footage several times. Shot video honestly does not look quite that bad. Nor do film conversions (i.e., 8mm film to DV tape, which is an ideal conversion master, not 8mm to DVD as the only copy).

Admittedly, testing conditions are an unknown, but it's not too far off from what I've seen over and over through the last number of years. I am a bit curious why the 4:1:1 is a slightly smaller resolution (about 75% size), which may or may not have increased the garblings a little beyond normal.

After anti-aliasing is applied, 4:2:0 will appear much closer to the original than 4:1:1.



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  #4  
07-18-2011, 02:02 AM
naripeddi naripeddi is offline
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Thank you very much Admin for the detailed reply. Much educational. Yes, with the examples, I can clearly see 4.2.0 is superor to 4.1.1. Luckily since I do PAL, I get 4.2.0 from the Canopus box.

I have captured a movie (Dr. No) from my Satellite Box (it is also a DVR, which claims it has MPEG-4 compression technology) using my Canopus ADVC-110 via the Firewire. I cannot 'copy' movies from the Satellite box due to copy-protction, so I had to use the ADVC to 'capture' the movie via S-Video. The quality of capture was good. Finally burnt to DVD and DVD also looks prtty good.

Question1: I captured the 'already recorded' movie from the Satellite box, sine I could not capture it while the movie was being broadcast. Would it have made a difference in quality while the movie was being broadcast, since I suspect the quality of the 'stored' video may be lesser than when it gets broadcast.

Question 2: I captured the movie with WinDV. The captured DV AVI has an aspect ratio of 4:3 (checked using Mediainfo), while I thought the movie was broadct as 16:9. While capturing, would WinDV have known what aspect ratio of the movie was? or woud ADVC have known what the aspect ration was, since it was feeding WinDV?

Question 3: I understand the ADVC captures the analog video stream from the Satellite box in DV format, compressing the signal using its own hardware DV codec (it said in MediaInfo that the codec was 'dvsd'). Is this Canopus's own DV Codec or Microsoft's? Can I change it while capturing for better quality? or would it be beneficial to change the codec after the capture is done, now that Matrox has released its codecs on their site free of charge?

I can say a lot of my current knowledge has been possible only because of this site with respect to video capture, DVD authoring, restoration, myths & misinformations. There are plenty of other sites on the subject of video, but this site is very 'special'.

Thanks.
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07-18-2011, 03:16 AM
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Quote:
Question1: I captured the 'already recorded' movie from the Satellite box, sine I could not capture it while the movie was being broadcast. Would it have made a difference in quality while the movie was being broadcast, since I suspect the quality of the 'stored' video may be lesser than when it gets broadcast.
It really depends on your model of DVR/TiVo. Years ago, some DVR boxes would re-compress the video to squeeze as much as possible on the box, as hard drives were quite a bit more pricey at that date. These days, and for several years now, DVR boxes simply dump the stream to a hard drive. So it's the same live or recorded.

Quote:
Question 2:
Can't answer this one tonight. Will have to reply to it later.

Quote:
Question 3: I understand the ADVC captures the analog video stream from the Satellite box in DV format, compressing the signal using its own hardware DV codec (it said in MediaInfo that the codec was 'dvsd'). Is this Canopus's own DV Codec or Microsoft's? Can I change it while capturing for better quality? or would it be beneficial to change the codec after the capture is done, now that Matrox has released its codecs on their site free of charge?
Yes, hardware Canopus DV codec. It cannot be changed. There no point in recompressing on-the-fly to another format, or even another DV codec. You can't undo what Canopus did to it. It is what it is, and that's all it is. It's DV, it's Canopus DV codec, the end.

Quote:
I can say a lot of my current knowledge has been possible only because of this site with respect to video capture, DVD authoring, restoration, myths & misinformations. There are plenty of other sites on the subject of video, but this site is very 'special'.
Excellent. Thanks much for your kind comments. We do try.

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  #6  
07-18-2011, 04:36 AM
naripeddi naripeddi is offline
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OK thanks.

Will wait for Q2 to be answered.

Regards
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