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Without caring for speed of processing, extra disk space needed, and other such factors, which of the following two is better (i.e. produces higher quality/better compressed video).

  1. Scale each individual image with imagemagick's convert, and then use that as the input to libav without any additional filters.
  2. Keep the images as is, but then apply scale video filter at the encoding time.
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1 Answer 1

It is going to depend on which of the two provides a higher quality resize option. If imagemagick's convert is higher quality than the scale of your encoder, then it will do better, if not, then it will be the other way around.

The one exception to this will be if there is any resolution dependent alterations made to the content along the way. If for example, you add text to the video, it would be much better to scale the images so that the you are creating new content at the native resolution of the finished video.

Anything you can avoid scaling you should and if the images are larger than the output, the earlier you can scale them down, the faster everything else will run anyway.

So with that in mind, I would generally scale down the images initially, if it was necessary to have the video at native resolution already when encoding, though most decent editing software will make it irrelevant because they will use the full quality image and put any new content at the native resolution and still combine everything to the proper resolution when rendering out at the end.

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This is basically what i've figured as well. The thing is that i was making a lesson about creating time-lapse, and i didn't want to end up recommending something that would be detrimental to quality. I ended up just doing the scale filter in the end, thinking that since these were JPEG files i was working with, i'd be forced to convert them to something lossless intermediately (so that i would not introduce additional JPEG artifacts), and that was going into the image editing, rather than video editing (thus out of scope of that lesson). –  Volodya Mar 1 at 12:05

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