[FFmpeg-user] Time shift

[Masen Baz]

Dear all
I need to make a time shift , i could create an ffm file .After googling a lot , i found that time shift can be done by ffserver.But it needs a date and time to start saving to this ffm file.
What i need is to make time shift by specifying the time by hours for example 6 hours only.The file must run in a loop and saving always the last 6 hours.
Can it be done by ffmpeg and ffserver?
RegardsMasen