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  1. Member
    Join Date
    Oct 2007
    Location
    United States
    Search Comp PM
    My input source is PNG image (image.png) and MP3 audio (audio.mp3). Currently I loop PNG input to make the video and stream-copy the audio, into the final video (final.avi):

    Code:
    ffmpeg -loop_input -f image2 -i image.png -r 1 -vcodec flv -i audio.mp3 -acodec copy -g 10 -qscale 2 -cmp 3 -subcmp 3 -mbd 2 -flags trell final.avi -shortest
    if the image for example is 1024x768, the encoding speed is sub 1FPS! I want to improve the total encoding time by first encoding 5 frames (1 keyframe with the following 4 frames), and then loop copy that video stream into final AVI, say 5 minute video. How can I achieve this?

    Thanks in advance!
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  2. Member
    Join Date
    Dec 2004
    Location
    Triptonia
    Search Comp PM
    Not with ffmpeg alone.

    you'd need to find a command line tool to concatenate avi's:
    create the section of video with ffmpeg,
    concatenate X amount of times based on audio duration (script it),
    mux audio and video.

    not exactly simple

    gl
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  3. Member
    Join Date
    Nov 2009
    Location
    United States
    Search Comp PM
    Use Mencoder.

    Concatenating / appending is super easy with Mencoder, check out the following example (for linux or mac):

    Code:
    mencoder -oac copy -ovc copy -o 'output_filename.avi' 'clip1.avi' 'clip2.avi' 'clip3.avi'
    Of course, in your case you would be appending the same thing over and over, in which case I would recommend either using a script to generate an appropriate Mencoder command, or using an Avidemux script.

    For more on appending clips with Mencoder (including a script example) check out this post:
    http://backstar.com/blog/2009/11/10/append-videos-with-mencoder/

    Explaining Avidemux scripting is really not in the scope of this reply, but basically you'd just need to use a simple Javascript loop. For example (this will concatenate a clip of 1000 frames 100 times):
    Code:
    for(var f = 0; f < 100; f++) {
      app.addSegment(0,0,1000);
    }
    To use the above code, do the following:
    • open the clip you want to repeat in Avidemux
      save the project file
      open the project file with a text editor
      add the for... code around the app.addSegment() part of the code
      delete the markerA=; and markerB=;
      save the project file
      open the project file in Avidemux
      save the video

    That might seem like a lot, but trust me, it's much easier than appending the same file 1000+ times, and much quicker than letting ffmpeg take its sweet time to convert every frame from the original image.

    EDIT: oh yeah, then you'll have to mux the audio and video. you can do this with a whole lot of programs, but i'd suggest using ffmpeg if you're willing to deal with the command line (which you probably are if you followed the above instructions)
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