[FFmpeg-user] Video streams extraction from DVR

[Gianluca Mei]

Hi,
my name is Gianluca and my job is extract video stream from DVR hard disk.
For example when I extract the video stream from unallocated space of the
hard disk partition I usually see that video with "FFplay", but there are
commonly 4 or more channels in the stream that alternate each other every
few seconds.
Are there techniques to join video coming from each channel and then
display each merged stream correctly?

Thanks for your answers