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  1. Member
    Join Date: Mar 2011
    Location: Paris, France
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    Hello

    I need to edit an MP4 video (AVC + AAC) so it starts between two key frames (ie. in VirtualDub, when hitting the button with a yellow key icon.)

    What is the right way to proceed?

    Thank you.
    Last edited by yetanotherlogin; 30th Mar 2014 at 18:37.
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  2. Member racer-x's Avatar
    Join Date: Mar 2003
    Location: 3rd Rock from the Sun
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    Long GOP formats like avc and mpeg-2 will require a full re-encode in VirtualDub........

    1) go to frame you want as start, hit the "Home" Key to mark as in.

    2) go the frame you want as last, hit "End" key to mark as out.

    3) export to your favorate compressor..............
    The memories of a man in his old age, are the deeds of the man in his prime.......
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  3. Member
    Join Date: Mar 2011
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    Done. Thanks.
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  4. Member
    Join Date: Nov 2002
    Location: United States
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    Originally Posted by racer-x View Post
    Long GOP formats like avc and mpeg-2 will require a full re-encode in VirtualDub........

    1) go to frame you want as start, hit the "Home" Key to mark as in.

    2) go the frame you want as last, hit "End" key to mark as out.

    3) export to your favorate compressor..............
    .........or use the external encoder feature of Virtualdub to encode to file of choice (ie...AVC/AAC.mp4 or AVC/AC3.mkv etc...)
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  5. VirtualDub has a function (under the Video menu) called "smart rendering". When it's enabled, I'm pretty sure it re-encodes the video around the cut point if necessary, then copies the rest. How well it works, or how easy it is to use when cutting AVC video I have no idea. I've never used it myself.
    I'd not trust VirtualDub to display anything frame accurately. Especially for AVC. Often you can use the key buttons to move backward and forward and keep landing on different frames. You might try opening the video with MPC-HC and using the shift key along with the left/right arrow keys on your keyboard. That'll jump between keyframes.

    If there's no keyframe where you need to cut, you could also try remuxing the MP4 as an MKV with MKVMergeGUI and then give cutting with MKV Cutter a spin.
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  6. Originally Posted by DarrellS View Post
    Originally Posted by racer-x View Post
    Long GOP formats like avc and mpeg-2 will require a full re-encode in VirtualDub........

    1) go to frame you want as start, hit the "Home" Key to mark as in.

    2) go the frame you want as last, hit "End" key to mark as out.

    3) export to your favorate compressor..............
    .........or use the external encoder feature of Virtualdub to encode to file of choice (ie...AVC/AAC.mp4 or AVC/AC3.mkv etc...)
    I think "export to your favourite compressor" was a different way of saying the same thing.
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  7. Member
    Join Date: Nov 2002
    Location: United States
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    Originally Posted by hello_hello View Post
    VirtualDub has a function (under the Video menu) called "smart rendering". When it's enabled, I'm pretty sure it re-encodes the video around the cut point if necessary, then copies the rest. How well it works, or how easy it is to use when cutting AVC video I have no idea. I've never used it myself.
    I'd not trust VirtualDub to display anything frame accurately. Especially for AVC. Often you can use the key buttons to move backward and forward and keep landing on different frames. You might try opening the video with MPC-HC and using the shift key along with the left/right arrow keys on your keyboard. That'll jump between keyframes.

    If there's no keyframe where you need to cut, you could also try remuxing the MP4 as an MKV with MKVMergeGUI and then give cutting with MKV Cutter a spin.
    A couple of good points. AVC is meant to be the finished output. Not editing. Trying to jump forward and backward in any editor will drive you batty. Even VideoReDo which IMO is the best program for editing out parts of a video has problems, especially if you try to do too many cuts.

    The second point of remuxing mp4 into an mkv container has worked well for me also. It seems to be easier to work with an mkv file instead of mp4. Smart rendering also crossed my mind. Virtualdub doesn't seem to have trouble with the end frame as it does with the starting frame which is why it is a good practice if you have a lot of cuts to do in Virtualdub to start at the end and work your way to the front. Less likely to have sync issues.
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