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I just did it again, using Panasonic's VFW DV codec for encoding the output file (literally converting HDV to DV). Speed was a little over 11fps.
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I don't use VitualDub because I'm on a Mac. If I remember correctly I once did a test down converting one frame in Photoshop and it really did a nice job but you'd have to be crazy to use it to downconvert a movie. |
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4:2:2 colour has 2 pixels in a row sharing the same colour info, all on one row. EDIT: Of course, the above assumes NTSC for DV. PAL DV uses 4:2:0 colour space, just like HDV does. |
I think what he was trying to say is, even at 4:2:0, with HDV you have more chroma samples per frame than with DV. When you downsize the HDV to SD, you effectively get higher chroma resolution than DV records (somewhat similar to effectively getting 4:2:2 in SD - actually closer to 4:4:4, I think, but I haven't had my morning coffee yet so I'm still groggy).
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You don't get MORE samples per frame. You get a different PATTERN: a 2 pixel by 2 pixel square instead of a 4 pixel x 1 pixel line.
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Chroma subsampling - Wikipedia, the free encyclopedia
A great graphical representation of 4:2:0, 4:1:1, 4:2:2 and 4:4:4 can be found at the above address. The number of SAMPLES of colour is identical in 4:1:1 and 4:2:0. The distribution is what makes the difference. And yes, 4:2:0 does have PERCEPTUALLY better colour representation (or at least less washed out) than 4:1:1, in my opinion. |
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Robert: INTERESTING... I'd never thought of it like that before. I'm sure that "in theory" comes into play somewhere. But of course, in downresing, you'd need to go to an intermediate codec that would support the increased colour sampling. Going to DV (4:1:1) would "throw away" all your gains by re-sampling to the 4 pixels by 1 pixel matrix.
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Part of why I say "in theory" is that I think (but I don't know absolutely for sure) the 2x2 block (in 4:2:0 interlaced footage) is by field (rather than by frame). It almost has to be. I'm not sure (hurts my brain to think hard enough to figure it out), but I don't think downsizing 1080i HDV (to interlaced SD properly) will really yield 4:4:4 color. It is safe to say though, that downsizing HDV (of any flavor) to SD should certainly yield better than 4:2:0 or 4:1:1 color. Yes, if you then "recorded" the downsized footage (saved the result) as DV (for example), it would then be 4:1:1 color (essentially, that is downsizing the chroma portion of the image yet again).
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Another part of why I say "in theory" is in recognition that the imaging system of the camera is a vital part of determining effective resolution. Just because a camera records an image in a particular format, doesn't mean the camera actually acquires at the resolution of that recording format (as a practical matter, the effective resolution never reaches 100% of the potential of the recording format - in the neighborhood of 70-80% is fairly typical).
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If you downconvert from an HDV tape so that DV exits via Firewire, the (presumably the same, and pretty cheap 'n' cheerful) downconverters are working to effect this. But shooting for the intended output is very good advice, and if you're only ever going to make DVDs (by definition SD) then it's far safer to film in the SD mode. This is because dropouts are far less damaging (and individual frames can even be worked on in Photoshop) and of course the audio is uncompressed. I too have difficulty seeing any real benefit in downconverting after I've done the HDV edit. There may be minute differences but hey - one HDV dropout is FAR more damaging from a visual pov. tom. |
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My advice is to shoot always in HDV, edit in HDV and let the final step do the downconversion. This allows you to mantain the maximun quality of your original footage even with color correction, fx, and preview renders (second generations). Also, you can reframe when you needed up to a certain degree without loosing quality in your final SD master. |
peter,
is the SD you shot showing up s 16:9?? I was wondering this myself because im buying a FX1 to shoot weddings with and want to know if its still widescreen 16:9 SD????? or anamorphic thanks Jason |
The FX1 has 16:9 CCDs, so everything you shoot will be widescreen unless you pillarbox it for 4:3 in the menu.
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