add streams to matroska files

Hi all, Is it possible to do this? I have muxed all my video files to matroska but want to occasionally:add a cover art picture add chapters add subtitle streams I can of course do this by remuxing the whole thing, but if the source files are several gigabytes in size it would be nice to be able to add such small streams without re-writing the entire file.

I don't think it's possible without remuxing. Besides adding chapters and subtitles won't increase the original file size of your several gigs by much at all unless I'm misunderstanding something here.

It's not the filesize i take issue with but rather the time needed for the entire operation. For a sub-1 GByte file it's ok but a multi-GB hi-def video file takes a long time to write out again.

Unfortunately there's no way to do that, but you can add "external" subtitles and covers. It's easiest and fastest solution. :)

I understand not adding streams, but why is there no way to change flags like aspect ratio without remuxing.