There are some open source DVR or PVR softwares out there on the Internet.
For linux O.S. :
. MythTV (supports MPEG4 and H.264)
. Freevo
. VDR
For windows O.S. : (build on the .NET Framework)
. MediaPortal
. MeediOS
For further information, click on the link below.
Comparison of PVR software packages - Wikipedia, the free encyclopedia
