Hi Víctor Paesa wrote: > Hi, > > On Dec 31, 2007 12:03 PM, Vitor Sessak <[EMAIL PROTECTED]> wrote: >> Víctor Paesa wrote: >>> On Dec 31, 2007 9:04 AM, Vitor Sessak <[EMAIL PROTECTED]> wrote: >>>> Víctor Paesa wrote: >>>>> Hi, >>>>> >>>>> The filter fps seems ignored in the ffmpeg command line.
[...] >> If you do >> >> ffmpeg -i input.avi -vfilters fps=1 output.avi >> >> where input.avi has a rate of 25 fps, you'll have >> >> Input -> 25 fps >> Filtered input -> 1 fps >> Output -> 25 fps >> >> The only problem is that the output rate (set in ffmpeg.c) is equal by >> default to the unfiltered input rate. The filter does its job, but I >> agree it would be more reasonable to set the default output rate to the >> filtered input rate. That would unfortunately have a small problem: >> imagine for example overlaying a 20 fps and a 30 fps movie together. The >> filter output will not have a fixed frame rate, so creating and setting >> a frame_rate field in the AVFilterLink structure will not make a lot of >> sense. A second problem would be to allow broken filters to set >> frame_rate to a value not coherent with the interval between timestamps. > > Yeah, I was thinking of patching vf_overlay.c as attached: I think that maintaining a constant frame rate could be handled by the filter framework instead of having to be handled by each filter. I've thought a bit more about the subject and have the following idea: 1- add a field named suggested_rate to AVFilterLink that would be the suggested frame rate of the output. 2- initialize this field by default by the input frame rate. 3- vf_fps will set it to its nominal value and vf_overlay will set it either as the highest one, the image rate or the subimage rate 4- in ffmpeg.c, the vf_fps filter will _always_ be inserted in the end of the filter chain (it's fast). It'll be given either the framerate specified by the -r command line parameter or if none specified by the value of suggested_rate in the end of the chain. What do you think? -Vitor _______________________________________________ FFmpeg-soc mailing list [email protected] http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-soc
