Bug Report MKV files created with OBS are slow to seek

[MasterEvilAce]

There has to be something wrong with MKV files that OBS Studio creates (using 0.15.4 64bit, Windows 10.)
Let's say I make a recording that is a 100 MB mkv file. Whenever I load the file in anything (Windows Media Player / VLC Player / etc).. it opens quickly, but if I try to seek anywhere in the timeline, it locks up for maybe 10 seconds before it resumes from the new time.

I'm not sure when this problem started happening, but I have one older MKV file from OBS that is 1 GB in size, and it doesn't have this issue. It was recorded in February. Anything recent has this issue. If I use other formats, such as MP4, there is absolutely zero issues seeking no matter what the size. I also have no issue loading and playing any MKV file from sources outside of OBS, even if they are multiple GBs in size.

For what it's worth, encoder is x264, 720p @ 30fps, CRF 23, keyframe=0, ultrafast, profile high

 

[antumbral]

I have this problem as well. A 30 minute long MKV file recorded using NVENC at 66mbps plays back fine but if I attempt to seek more than about a minute into it, the video player hangs (tried both mpc-hc and the win10 Movies app).

 

[Simes]

Might be worth setting keyframes to 2, then you'll get a keyframe every 2 seconds rather than the default (which is, I think, 5). That means the decoder will need to spend less time rebuilding intermediate frames when you do a seek.