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  1. Hello.
    I have several videos rendered in 2 pass x264 that include still images shown for a long time (a background for audio). Is it possible to reduce video size while not affecting the quality (re-encoding) of the rest movie?
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  2. x264 only codes difference to previous pictures so these are compressed very well already if they are shown for less than the keyframe interval (--keyint). If these span over a number of GOPs you could delete every repeating GOP (except one) and write a timecode file (for e.g. mkvmerge muxer) to extend the time of said GOP. But it's complicated and may not be worth it. Also, you can't expect all players to play and/seek properly.
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  3. There are several moments in a video with same still image (some of them overlapped by another image for a short - several seconds to several minutes - period of time) but different length. They can last 30 mins to 1+ hour. I have mkvtoolnix but don't know how to do difficult operations (like directly editing video stream in it) other than muxing/demuxing. Player support doesn't matter if VLC/MPC supports it.

    Does mkv support several streams to be played in an order in a file seamlessly? If so, I can choose another codec for still image parts.
    Last edited by Mavrodi; 23rd Nov 2016 at 13:48.
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  4. Teaching you is too much work, sorry. Needs understanding of variable framerate and other basics. Maybe someone else can point you to a tutorial or sth.

    Next time try --keyint infinite and/or reduce framerate when you are encoding only stills.
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  5. Originally Posted by Mavrodi View Post
    Does mkv support several streams to be played in an order in a file seamlessly? If so, I can choose another codec for still image parts.
    It works with segment linking to some extend. If you already know how to split, re-encode certain parts and re-append you should be able to do it. Just re-encode the still parts using --keyint infinite. Then try re-appending. If re-appending produces errors try re-appending using ffmpeg cancat demuxer or use mkv segment linking.
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  6. Thinking about it, doing VFR is not so complicated. Just needs several splitting operations.
    1. Split file into parts with still image (each image as separate file) and those without.
    2. Then on all parts with still image:
    - De-select audio track and split off only e.g. 1 frame
    - re-merge with audio
    (so only 1 GOP video with old audio)
    3. Then re-append all parts

    No deep knowledge required. Can all be done using MKVToolNix GUI.
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  7. Thanks a lot, this will work.
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  8. Try CRF instead of 2pass VBR, because maybe you set average bitrate too high and encoder forces a ceratain bitrate to those image areas even if it is not needed.
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