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  1. Member
    Join Date: Mar 2008
    Location: United States
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    I'm frustrated trying to make a clip run 'fast action' (i.e., I have a 60-sec clip which I want to dash through in 30 sec)

    As nearly as I can tell, changing the frame rate isn't changing the elapsed time, just the 'density' of frames.

    I've tried two things:

    1. With ffmpeg, trying to 'force' a different frame rate for the original clip. So, if foo was recorded at 30fps, do

    ffmpeg -r 60 -i foo.avi -r 30 fast-foo.m2v

    but that seems to make no difference.

    2. With Cinelerra, using the video-effect 'ReframeRT' , which the doc describes for 'slow-mo' but not for 'fast action'.

    This should be simple, right??

    What should I try next??
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  2. Get Slack disturbed1's Avatar
    Join Date: Apr 2001
    Location: init 4
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    Try mplayer with

    mplayer -speed

    From man mplayer
    -speed <0.01-100>
    Slow down or speed up playback by the factor given as parameter. Not guaranteed to work correctly with -oac copy.
    Changing the frames per second won't speed up nor slow down the footage. It will only cause the encoder to drop (lower fps) frames or repeat/blend (increase fps) frames.

    You'll have to create a fifo, output mplayer to that fifo and pipe it into an encoder.

    mkfifo video.yuv &&\
    mplayer -speed 100 -noconsolecontrols -benchmark -nosound -noframedrop -noautosub -vo yuv4mpeg:file=video.yuv \
    -vf what,ever.filters,you,want inputfile.foo & cat video.yuv | mpeg2enc -f 8 -o video.m2v


    Be sure to pass -a (aspect ratio) and -n (n(tsc),p(al) ) to mpeg2enc, at least. man mpeg2enc for other options.
    Linux _is_ user-friendly. It is not ignorant-friendly and idiot-friendly.
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  3. Get Slack disturbed1's Avatar
    Join Date: Apr 2001
    Location: init 4
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    Ok, well that didn't work on every file I just tested it with.

    This does those, so play around with it to see what you can do with it BTW, -speed 1 is real time

    mencoder file.avi -speed 20 -vf scale=720:368,hqdn3d=3:2:3:2,expand=720:480 -ovc xvid -oac pcm -xvidencopts fixed_quant=2 -o out.avi
    Linux _is_ user-friendly. It is not ignorant-friendly and idiot-friendly.
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