Avidemux: How to increase MKV muxer keys?

[mercy]

I have an FLV that has no keys. I want lots of keys for the video to be navigateable back and forth via keys.

I open the FLV in Avidemux 2.6.13 and select MKV muxer, Video: / Audio: Copy. Save as MKV. It adds a couple of keys. Is there a way to edit that MKV conversion script so I can increase the number of keys it adds by default?

[sneaker]

You mean the number of keyframes? You need to re-encode with a lower keyframe interval if you want more keyframes.

[mercy]

But how does MKV muxer insert keyframes into a video? Is it a default MKV structural law, it just has keyframes at intervals?
I'm asking because a simple copy is lightning fast and re-encoding the video takes 30-70 minutes and yeah, its a lot of time.

I thought I could edit that default MKV muxer script or INI so it inserts more keyframes via a simple video/audio copy.

[sneaker]

The mkv muxer only searches and marks the keyframes already exisiting in the underlying videostream. It cannot add any additional ones. There is no way around re-encoding.

[mercy]

Strange. With the original FLV in MPC-HC I can't jump forward / backward to keyframes. Saved with MKV muxer I can jump to the new sparsely populated keyframes.

Anyway: I researched it and found Datamoshing, there I just did the reverse, a fast way is Mpeg4 ASP (xvid4) takes only 5 minutes to create a keyframe-rich MKV, __but__ it must be destructive because file size decreases, that could mean data loss and I need to see small fonts in those zoomed in videos. Also time loss is a big no-no in this project. So better I just copy to MKV and leave it there without time loss and gain some keyframes to jump to.