On 10/29/18, Jim DeLaHunt <list+ffmpeg-u...@jdlh.com> wrote: > On 2018-10-26 11:57, S Andreason wrote: >> Hi, >> >> Does zoompan not work outside the range 1 .. 8? >> > Nearly correct. The zoompan filter accepts values for the zoom parameter > between 1 and 10. Any values below 1.0 are set to 1; any values greater > than 10.0 are set to 10. > > Also, it's helpful to be very clear about the conceptual model the > zoompan filter uses. The filter starts with an input image (or frame of > an input video). It sets up a coordinate system based on this image: > origin at top-left, with +x to the right and +y downwards. A zoom > argument of /k/ is interpreted as if the input image was drawn /k /times > its original size, or equivalently, that the output image is 1//k/ the > size of the input image. The x and y arguments to the zoompan filter are > interpreted in this coordinate system, but clipped so that the output > image (after zoom adjustment) will stay completely within the input image. > > The core motivation for the filter seems to be implementing what some > call the "Ken Burns effect", making a video image which pans over an > input image, and zooms in to only show part of the image at a time. It > is not well-suited to general transformations, given its limitations on > zoom level, its refusal to pan beyond the boundary of the input image, > and the absence of a rotation capability or generalised affine > coordinate transformations. > >> I want to generate an overlay to zoom in, have the input png start >> small, and grow to half the video size, like from 20 to 320 in width. >> Starting the zoompan at z=0.1 does not seem to work. > Take a look at the *pad* filter <http://ffmpeg.org/ffmpeg-all.html#pad>. > That generates an output frame which consists of an input frame with > padding around it. >> Also if the first filter was successful, I need to crop it so that it >> grows over time. I am having trouble getting crop to adjust based on >> the frame number. From my testing it seems n in this case starts at 0 >> when the enable between starts, instead of the output video frame >> number like the other filters I have been using. > I'm not sure I follow what you mean by "when the enable between starts". > My experience with the *zoompan* filter is that the /in/ parameter > (input frame number) is 2 for the first frame, rather than 0 as is usual > for ffmpeg. I think that this is partly a bug (see > <https://trac.ffmpeg.org/ticket/7242>). Partly this appears to be a > design decision by the original developer, to use cardinal numbers > instead of ordinal numbers.
That bug have long be fixed in master branch. I just closed it. >> Is there a manual or wiki with more information then at >> https://ffmpeg.org/ffmpeg-filters.html ? > If you want to do serious work with the zoompan filter, my experience is > that the documentation isn't adequate, and you need to read the source > code in ffmpeg/libavfilter/vf_zoompan.c, lines 153-250, function > output_single_frame(). >> Thank you >> > I hope this is helpful for you. > —Jim DeLaHunt, Vancouver, Canada > > -- > --Jim DeLaHunt, j...@jdlh.com http://blog.jdlh.com/ > (http://jdlh.com/) > multilingual websites consultant > > 355-1027 Davie St, Vancouver BC V6E 4L2, Canada > Canada mobile +1-604-376-8953 > > _______________________________________________ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".