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interlacing DV anamorphic
Posted by yogatic
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Re: interlacing DV anamorphic February 22, 2009 12:27PM |
You don't have to worry about that as that's a format and if you are going out to TV land, but if you're going out to web you need to deinterlace your video.
I could go much further on this, but lots been covered and it's hard to explain in a short web post, but here's an article on it.
[www.dvcreators.net]
www.strypesinpost.com
I could go much further on this, but lots been covered and it's hard to explain in a short web post, but here's an article on it.
[www.dvcreators.net]
www.strypesinpost.com
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Re: interlacing DV anamorphic February 22, 2009 12:35PM |
Frankly, now nothing. What you're seeing is not a problem. It's not an artifact or flaw. It's inherent in how interlaced video works.
Most people, even non-video-pros, are familiar with the term "frames per second." It's an easy concept to wrap your head around, if you think in terms of film. A film camera pulls the film down, exposes a frame, then blocks the light coming from the lens and pulls the film down again to get ready to expose the next frame. Film cameras (usually) do this 24 times a second, for a frame rate of 24 frames per second.
But interlaced video doesn't work like that. Interlaced video doesn't record a whole frame at a time. Rather, it records fields. The odd-numbered lines of a frame comprise one field, and the even-numbered lines comprise the other field.
These fields are not recorded at the same time. In NTSC-land, each field is recorded approximately 1/60th of a second apart. So you get an even field, then a sixtieth of a second later an odd field, then a sixtieth of a second later another even field.
(It's the same in PAL-land, only with slightly different timing.)
Prior to about ten or fifteen years ago, all televisions displayed the fields in exactly the same way they were recorded: first the even field was drawn on the screen by the electron gun inside the picture tube, then a sixtieth of a second later, the odd field was drawn. You don't see the fields because the phosphor that lines the inside of a television tube doesn't just blink off when it's been exposed to the electron beam; it continues to glow for a little while, creating the illusion of a continuous moving image. That's why you can't perceive the fields on a tube television.
The reason you can see the fields in your canvas and viewer is because Final Cut (when the scale is set to 100%, and only then) draws both the even and odd fields together, to show you a whole frame. What you're essentially seeing is two different images captured at two different moments in time, 1/60th of a second apart, laced together like fibers in a sweater. This can throw some people, because they're not accustomed to the fact that televisions don't work that way.
Now, tube televisions aren't all that common any more. It seems like most TVs on the market now use LCD screens, which are an entirely different display technology. But the people who make LCD televisions aren't idiots; they know that they have to work properly with interlaced signals. So various tricks are employed to make interlaced video look right on LCD screens.
The exception ? and a whopper of an exception it is ? is your computer screen. A computer screen and an LCD television are the same thing, electromechanically speaking. The difference is that an LCD television contains electronics that manipulate the interlaced signal to make it look right. A computer screen doesn't. That's why your material looks wonky on Youtube.
So for best Youtube results, and best results when playing back on a computer in general, deinterlacing interlaced video is recommended. The best way to do this is with Compressor. Once you've exported your timeline as a Quicktime movie, take it into Compressor for deinterlacing, scaling and whatever other operations are necessary to get it into your deliverable format.
Compressor offers three different types of deinterlacing. I don't remember the terminology because I'm not in front of my system today, but it basically amounts to "fast," "better" and "best." The "fast" option just line-doubles; it discards every other field, and duplicates the remaining field in order to make up the now-missing scan lines. Nobody likes this option, but it's handy if you just need to generate a quick approval Quicktime or something. The "best" option is really slow, but produces very good results through the judicious application of complicated math. The "better" option is, as the name would suggest, a compromise. The only way to tell whether you're happy with the "better" option is to do some tests.
(For myself, I always use the "best" option. It takes about an hour on an eight-processor system to process two minutes of standard-definition video this way, but that's acceptable in my circumstances.)
Most people, even non-video-pros, are familiar with the term "frames per second." It's an easy concept to wrap your head around, if you think in terms of film. A film camera pulls the film down, exposes a frame, then blocks the light coming from the lens and pulls the film down again to get ready to expose the next frame. Film cameras (usually) do this 24 times a second, for a frame rate of 24 frames per second.
But interlaced video doesn't work like that. Interlaced video doesn't record a whole frame at a time. Rather, it records fields. The odd-numbered lines of a frame comprise one field, and the even-numbered lines comprise the other field.
These fields are not recorded at the same time. In NTSC-land, each field is recorded approximately 1/60th of a second apart. So you get an even field, then a sixtieth of a second later an odd field, then a sixtieth of a second later another even field.
(It's the same in PAL-land, only with slightly different timing.)
Prior to about ten or fifteen years ago, all televisions displayed the fields in exactly the same way they were recorded: first the even field was drawn on the screen by the electron gun inside the picture tube, then a sixtieth of a second later, the odd field was drawn. You don't see the fields because the phosphor that lines the inside of a television tube doesn't just blink off when it's been exposed to the electron beam; it continues to glow for a little while, creating the illusion of a continuous moving image. That's why you can't perceive the fields on a tube television.
The reason you can see the fields in your canvas and viewer is because Final Cut (when the scale is set to 100%, and only then) draws both the even and odd fields together, to show you a whole frame. What you're essentially seeing is two different images captured at two different moments in time, 1/60th of a second apart, laced together like fibers in a sweater. This can throw some people, because they're not accustomed to the fact that televisions don't work that way.
Now, tube televisions aren't all that common any more. It seems like most TVs on the market now use LCD screens, which are an entirely different display technology. But the people who make LCD televisions aren't idiots; they know that they have to work properly with interlaced signals. So various tricks are employed to make interlaced video look right on LCD screens.
The exception ? and a whopper of an exception it is ? is your computer screen. A computer screen and an LCD television are the same thing, electromechanically speaking. The difference is that an LCD television contains electronics that manipulate the interlaced signal to make it look right. A computer screen doesn't. That's why your material looks wonky on Youtube.
So for best Youtube results, and best results when playing back on a computer in general, deinterlacing interlaced video is recommended. The best way to do this is with Compressor. Once you've exported your timeline as a Quicktime movie, take it into Compressor for deinterlacing, scaling and whatever other operations are necessary to get it into your deliverable format.
Compressor offers three different types of deinterlacing. I don't remember the terminology because I'm not in front of my system today, but it basically amounts to "fast," "better" and "best." The "fast" option just line-doubles; it discards every other field, and duplicates the remaining field in order to make up the now-missing scan lines. Nobody likes this option, but it's handy if you just need to generate a quick approval Quicktime or something. The "best" option is really slow, but produces very good results through the judicious application of complicated math. The "better" option is, as the name would suggest, a compromise. The only way to tell whether you're happy with the "better" option is to do some tests.
(For myself, I always use the "best" option. It takes about an hour on an eight-processor system to process two minutes of standard-definition video this way, but that's acceptable in my circumstances.)
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Re: interlacing DV anamorphic February 22, 2009 12:56PM |
I've never used iDVD, so I can't say anything about that.
As for the other, two possibilities come to mind. First, you probably just never noticed the difference between fields before. The time interval between them is only 1/60th of a second, so there needs to be some pretty significant horizontal movement in the shot for the interlacing to be obvious. Second, it's possible that you were shooting a progressive format before, either 24p or 30p (though you should never shoot 30p).
As for the other, two possibilities come to mind. First, you probably just never noticed the difference between fields before. The time interval between them is only 1/60th of a second, so there needs to be some pretty significant horizontal movement in the shot for the interlacing to be obvious. Second, it's possible that you were shooting a progressive format before, either 24p or 30p (though you should never shoot 30p).
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Re: interlacing DV anamorphic February 22, 2009 01:35PM |
>learned to check the de-interlace box in movie properties in QT
>That seems to have solved the problem instantly.
That's just to display it properly on your computer monitor (which is progressive) so you don't see the lines.
As I mentioned earlier, if you are going out to web, you should deinterlace, but you don't have to do it if your work is going out to TV land.
www.strypesinpost.com
>That seems to have solved the problem instantly.
That's just to display it properly on your computer monitor (which is progressive) so you don't see the lines.
As I mentioned earlier, if you are going out to web, you should deinterlace, but you don't have to do it if your work is going out to TV land.
www.strypesinpost.com
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