As I remember one of my recent AIM conversations with DigitAl56k from DivX Corp (No I don't have a copy of the message). He said he uses BlackmanResize or LanczosResize. I asked him what he use more. He replied depending on a scale factor. I didn't ask him but in DivX Corp what is a factor scale? If I remember that name right?
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I'm guessing he's referring to upscaling or downscaling of the frame size. Some filters work better in one direction than the other. I think Lanczos works better for upscalling, but other members may give you better info.
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Originally Posted by redwudz
I use 720x400 for 16:9 and 720x544 for 4:3. Not sure if those are upscaling or downscaling? -
I suspect by "scale factor" he meant how much he was resizing. So downsizing from 720x480 to 320x240 is a larger scale factor than scaling to 640x480.
BlackmanResize() is supposed to produce less ringing at sharp edges than Lanczos4Resize().
http://avisynth.org/mediawiki/Resize -
Originally Posted by jagabo
The dimensions I gave are again: 720x544 for 4:3 and 720x400 for 4:3. -
And what are you doing with the video ?
Are you resizing for DVD, or for Divx playback ?
Are you resizing from these resolutions to something, or from something to these resolutions ?
You have asked a question that requires a context to answer, but you have not provided that context.
Describe exactly what it is you are doing. What is your source, what is your target and how are you getting there ?Read my blog here.
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Originally Posted by rocky12
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Either keeping the video on my machine for my Philips player.
DivX playback. I prefer DivX over XviD.
Just the resolutions I gave. Let's say this, if my movie was XviD or DVD set at 16:9 then I use 720x400 or if the XviD is 4:3 then 720x544.
Originally Posted by guns1inger -
For the very small amount of scaling you are doing, you won't notice a difference between Lanczos, Blackman or Bilinear. The scale factor covers whether or not you are going up or down, and also by how much. As a general rule, I use Lanczos for most upscaling, as I don't upscale by large amounts. For scaling down, Bilinear is usually good enough. Again, I don't tend to down scale by large amounts.
You will usually get better quality from NTSC 4:3 if you go to 640 x 480, as you are only adjusting for the non-square pixels, and not actually scaling the video. If you go to 720 x 544 then you are scaling the video, and run a higher rick of introducing artifacts and problems.Read my blog here.
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Originally Posted by guns1inger
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Why don't you leave the frame at 720x480 and use the Divx aspect ratio setting. See if your player handles it properly.
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16:9 is a different kettle of fish because the pixels are different shape to 4:3.
For 4:3 it is simple. The horizontal size of the pixels is slightly wider than they are tall. When your TV plays them back, it squashes them slightly to get the image right. When you resize to 640 x 480, you are simple squeezing the pixels back to square.
For 16:9 you have two different complications. The first is that the pixels are shaped differently to 4:3. The 1:1 equivalent for NTSC 16:9 is 854 x 480. If you resize to 640 wide, then you have to resize to 360 high.
But : 16:9 is not a film aspect ratio. Film aspect ratios cover a very wide range. The film equivalent of 16:9 is 1.778:1. However if you put a film shot at 1.85:1 or 2.35:1 in a 16:9 frame, you get black bars in the image. If you simply resize to 640 x 360 (or 720 x 400) then you keep these bars and encode them needlessly. So working with widescreen involves correctly cropping off all the bars, then resizing to maintain the correct display aspect ratio.
Are we having fun yet ?
This is why many use something like AutoGK, which takes care of all of these decisions.Read my blog here.
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Originally Posted by jagabo
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Yes I am having fun. It's better then synch. What should PAL 4:3 and 16:9 resolutions should be?
Originally Posted by guns1inger -
PAL 4:3 is 720 x 768 (the pixels are taller than wider for PAL 4:3). Widscreen is even wider than NTSC - 1024 x 576.
Personally, I let AutoGK do all the hard work for me. I am happy with a 640 width, and 10MB/m bitrate. For true PAL 16:9 (i.e. digital broadcasts) I get 640 x 368 resolution 1:1 PAR. However if I were encoding a PAL DVD that was wider, the resolution would be different (e.g. 2.35:1 is 640 x 272 1:1 PAR)Read my blog here.
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Originally Posted by guns1inger
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Originally Posted by rocky12
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Originally Posted by jagabo
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If you're using square pixel encoding the the aspect ratio is the same as relative frame dimensions. There is no single "right" frame size. You can use the same 720x400 or 640x368 you use for NTSC.
Divx and Xvid are happiest with frame sizes that are multiples of 16. That's why the above listed frame sizes are not exactly 16:9 ratios.
Or, as I said earlier, leave the frame size at 720x576 and use the DAR flags to set the AR. Most newer players respect the DAR flags.
If you're going to reencode an Xvid file to Divx it is probably already using square pixel and the right aspect ratio so there's no need to resize. -
Originally Posted by jagabo
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I said I rather change it.
Is 854x480 upscaling or downscaling? Is 640x480 up or downscaling? Is 720x768 upscaling or downscaling and is 720x400 upscaling or downscaling? -
Originally Posted by rocky12
Originally Posted by rocky12
Originally Posted by rocky12 -
Originally Posted by jagabo
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Originally Posted by jagabo
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Changing the resolution is the DEFINITION of upscaling and downscaling.
Upscale: Scale up, make bigger, increase the frame size
Downscale: Scale down, make smaller, decrease the frame size -
Originally Posted by jagabo
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As I've said several times now, nobody can tell you if those are upscaling or downscaling unless you specify what the source frame size is.
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