Asterisk .h264 file conversion

I need to take a Screenshot of the Video stream within a call. I’m aware of the “Record” Dialplan Application. But with that I have a properitary .h264 file which I can just use for Playback.

Is there any way to convert the properitary .h264 file to something useful? With ffmpeg or something like that?

The .h264 is a stream of H264 frames, basically, with no container format. I’m not aware of how to do any conversion from it.

In theory I should then be able to put it with ffmpeg or avc2avi into an container format. But exactly that doesn’t work for some reason