Appending audio/video data to an MKV file

[ury]

Hi all,
Is there a tool (such as ffmpeg) which provides the ability to append an MKV file to an existing MKV file? By "appending", I mean that the action will not create a new file but rather increase the size of the first file without copying it.
Both files have the same audio and video streams (H.264 and MP3).
Thanks,
Ury

[sneaker_ger]

mkvmerge

/edit:
misread. You mean without creating a new file? No, I don't think there is such a program. With copying you can use mkvmerge.

[ury]

Thanks.
Are there any other A/V containers for which it can be done?

[Ghitulescu]

generally speaking, the APPEND function as you imagined it, is avoided for data safety reasons. Most if not all programs try to keep the source intact in case SOMETHING might go wrong, in which case you'd loose EVERYTHING.

[ury]

Funny thing, I need it as a part of a crash recovery mechanism.
I'm recording an A/V feed, and I want to periodically add a segment to a another ("backup") file, since a mixing solution didn't work for me.