If you just want to split files or learn about the VFR issue first watch this tutorial. > Split large files into smaller shorter clips without having to use a video editor. > Files are muxed with time stamps and thus 100% audio & video sync. > No Re-Encoding and thus no time wasted with the computer being busy. > 100% Quality Preserved from the original file. > 100% Free Programs (real programs not some spyware infected crapware) You do not need to be an XSplit user to make use of these tutorials, just if you have a FLV you want to "convert" but I have paid special attention to a need XSplit users have because the FLV videos have VFR (Variable Frame Rate) and thus many other conversion methods will result in a audio/video sync issue. You can still make use of some older tutorials like VAC tuts and things but today I am focusing on some video editing information. Instead, they endorse Lanczos, Spline, or "Blackman" resampling.#1 I had a couple of tutorials a while back when I was streaming SC2 and other games almost daily to help other users I just updated these tutorials for 2013. I also found documents (scene rules) from the video encoding scene that explicitly ban bicubic filtering for downsampling. Here are some more examples of image interpolation algorithms, including the ones I mentioned above. (Well, unless you pick the nave Pixel Resize or Nearest Neighbor algorithms.) Other examples You'll get good results no matter which algorithm you pick. Make the image as small as you want, and you have complete fidelity- within the bounds of the number of pixels you've allowed. You're simply reducing precision and resolution by discarding information. Reducing images is a completely safe and rational operation. That said, this is not what is typically recommended for video encoding – and some commenters have raised doubts about Atwood's expertise in the field. His rule of thumb was to use bicubic interpolation for downsampling and bilinear interpolation when upsampling. It turns out Jeff Atwood did a comparison of image interpolation algorithms. I don't think there's a good reason for using them in video. Hqx as well as 2xSaI filters are used for pixel-art scaling (e.g. It is more computationally expensive but usually described as very high quality and can be used for up- and downsampling. Lanczos resampling involves a sinc filter as well. I don't think the overall increase in processing time is worth using them. Spline and sinc interpolation use higher-order polynomials and are therefore harder to compute than bicubic interpolation. According to this page, it should produce better results when downsampling. It's – as far as I'm concerned – the most popular.Īrea averaging uses a mapping of source and destination pixels, averaging the source pixels with regards to the fraction of destination pixels that are covered. It's not the best algorithm, but rather fast.īicubic interpolation uses a 4x4 environment of a pixel, weighing the innermost pixels higher, and then takes the average to interpolate the new value. See that bicubic interpolation results in smoother edges? That's a very general statement … but you can find an overview of image scaling algorithms here.īilinear interpolation uses a 2x2 environment of a pixel and then takes the average of these pixels to interpolate the new value. Different algorithmsĪs an example, here's bicubic vs. You can't always predict the result, but just see what works best for you. You therefore shouldn't worry about huge differences there.įact is, as always when encoding video, that the result heavily depends on the source material. These filters all have only a marginal impact on file size. More importantly, they have an impact on the quality when upscaling, because you need to generate data where there isn't in the first place. It could be argued that the resizing filters don't matter that much when you downscale a video. The recommendations may vary depending on content type and application area. These are based on material I've read over the years, and from what I've seen used in the industry. When sampling up: Use Bicubic or Lanczos filtering. When sampling down: Use Lanczos or Spline filtering.
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