Lanczos can use additional parameter here: param_a is defined as "the number of filter taps", I don't know its default value. Lanczos can use additional parameter here: param0 is defined as "the width (alpha)", its default value is 3.įFmpeg can use zscale with lanczos, spline16 and spline36 parameters. Variants of the algorithm are defined by "the number of filter taps".įFmpeg can use scale/ sws_flags with lanczos and spline parameters. Spline ( documentation), it has a few variants: Spline16, Spline36 (and others) Lanczos ( documentation), it has a few variants: Lanczos3, Lanczos4 (and others)
There are two filters best to downscale the video ( source): Note: I've read that -sws_flags method can be sometimes buggy ( source) and in these cases FFmpeg will use its default filter, not the selected one. There are three main methods with these options to select resize filter: It looks like scale is the default scaler and zscale requires additional library to enable it. I would like to refrain from first scaling down the images or creating video files from them and then overlay these videos.There are two main options to scale the video in FFmpeg: scale ( documentation) and zscale ( documentation). However with this commando FFmpeg complains that -filter_complex and -vf can not be used in the same commando. The values in scale and pad are derived dynamically and correspond to the video height and video width. Here's what I have so far: -i 'input_video.mp4' The issue here is that the images might be bigger than the video, but they should be scaled down (keeping the aspect ratio) and the missing spaces should be filled with black. I am trying to overlay a video with multiple images at different points in time.
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