Trying to teach benefits of lossless?
Forum,
I have spreading the gospel of lossless and am going back and forth with a fairly smart fellow. Can you verify (or vilify) the following quotes from my esteemed associate? There are different levels of compression and different results. Starting from a limited bandwidth analog signal, IMO there is little to loose when working at highest quality compressed workflow. But that's just me. I disagree, I hate compression for capture. The video input ADC device will limit a lot of the bandwidth and have a lot to say about the dynamic range of the video signal (color is amplitude modulated). Firstly not capturing from S-Video it will apply the comb filter and kill a lot of Luma bandwidth. Secondly not all the video ADC are created equal, personally I found that the ADC in a Digital8 camera (S-Video input) is very good. Seems OK Note that the chroma signal is recorded with the same reduced bandwidth in both 8mm and Hi8 formats (only the luminance FM modulation was increased from 1.2 to 2.0MHz). Chroma AM modulation results in a resolution (for both formats) of only around 30 lines horizontally. Compare with about 400-420 lines on luminance channel for Hi8. So the 4:1:1 NTSC rates applied by DV format are more than double of what Hi8/8 can provide and more than appropriate for capture. Is this true? I thought DV was to be avoided if possible and an S-Video capture would be superior for editing. PS: The 4:2:0 by PAL is a bad compromise solution IMO... like always in PAL the regulators tried to screw consumers and provide sub-par video recording compared to their over-taxed "pro" market. |
Not an expert, but since nobody else has chimed in yet, I can at least say a bit having read a lot on the forum and being a lossless capture guy myself.
It's rare to change somebody's mind on things. Perhaps being a champion of or a promoter of lossless is a better approach. If somebody has it set in their mind and is resolute in their belief, probably not much of a point to argue. I would say promoting lossless to those who have an open mind and/or are new and want to understand why they should consider lossless is a much more productive endeavor. :) This forum taught me that if I'm going to be serious about restoration of video, then you should start with lossless. Furthermore, you should try to get the best colorspace you can to start with, i.e. 4:2:2 better than 4:2:0 or 4:1:1, because if you are doing color correction, you want to have as much color resolution as you can so you are not being any more destructive to the original than you have to. I've read MPEG can do 4:2:2, but I think the standard is 4:2:0. I think having the video in a lossless format is also essential to do as little harm as possible with other types of restoration. Having come from scanning and restoration of photos or camera negatives and using Photoshop to clean and color correct, I used a lossless format like TIFF for my images before compressing the final result to a JPEG. If you work on JPEGs in Photoshop and apply curves, filters, etc. You will likely have a lesser quality JPEG in the end, than if you stayed lossless until the end. Why? Because the operations are destructive when it is not a lossless image being worked on. When it is lossless, this issue is minimized or removed. For image scanning, there are arguments about say 8-bit SRGB Color Space vs 10-bit AdobeRGB Color Space. So there's always the theory of it, versus the actual results one can measure with their eyes. So, like 4:2:2 vs 4:2:0, perhaps it's what one can observe, and it may be case by case with the video/image or the person. Also, it may boil down to what one can notice. Some of us are much more detail oriented or particular about things. Those that are not, may not be able to tell as much difference. No big technical arguments I have. I understand the theory of it, and have seen the benefits of using lossless over compressed. If someone doesn't see those results, then they are going to be quite difficult to convince. Keep trying to spread the good word. :salute: Try to educate one individual at a time. But first, evaluate their openness to the subject matter.:wink2: |
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Capturing using the S-Video input on a D8 camera is limiting as you lack any control of the levels (other than possibly in service mode, haven't checked), and you are forced to use DV compression. The ADC itself seems ok, after all the video signal will go through the cameras ADC for timebase correction on playback and it doesn't seem to cause any issues there. Quote:
4:2:0 is a bit complicated as well, PAL has reduced vertical color resolution due to the format, and additionally the color signal from tapes (in both PAL and NTSC) will go through a comb filter in the playback device (to reduce crosstalk, not as extensive as what will happen in the ADC with a composite signal), even when using S-Video. I.e the color is going to be smeared a bit verically, but I don't know if it's technically 1/2 vertical resolution still. |
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