Summary: I have two separate problems with AviDemux on some H264-encoded video. Sometimes AviDemux cannot scroll/seek through the video. Other times, it will mysteriously eliminate frames (~1-2 minutes of playtime) from the end.

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Hello, I am a newbie to video editing, so please excuse poor terminology.

I am trying to split some AVI's and MP4's I have downloaded from the internet, so that I have 3 smaller files instead of 1 big one.

I have been using AviDemux with decent success on most of the AVI/MP4's. But with some files this is impossible. AviDemux will open the video, and will play the video if the play button is pressed. However, I cannot move the scroll bar to any position (it will always go to 0:00) and upon pressing the next/previous keyframes button, I get the error "Cannot go to next keyframe."

If I set one split point at 0:00 and another at 0:10 (by using the play button and waiting 10 seconds before setting the endpoint; I cannot scroll) and then save, AviDemux does not stop saving the file. The aborted video file produced is obviously way too big in size to be a 10 second video.

I don't know anything about keyframes, but that seems to be the issue here. I have been unable to find a good answer via google about this problem.

Other times, AviDemux will split files correctly, but the seek bar ends too early. For example, AviDemux will open a 60 minute movie but the scroll bar only encompasses 59:30. The final frame shown in avidemux is not the final frame of the movie, so there is no way for me to split this video without losing the ending! VLC plays the videos without a problem, so I don't think the file is corrupted.

80% of my files, AviDemux works without any problems. But it seems that for some AVC-encoded files, these problems occur.

I don't know if this is relevant, but I cannot get Virtualdub to recognize any H264 VFW decoder I install. I have 64Bit Windows 8 with 32 bit AviDemux, decoders, etc.

I have done some reading, but cannot find a solution. Any tips on troubleshooting?

Thank you!
-Ichigofan