... surveillance,CMS, Audio; -Dual stream technology 4 Channel DVR Recorder H.264 H.264 compression, high definition4CH Full D1 Real ... upgrade and backup, and USB hard disk, USB recorder and network backup.Multitask, local multi-screen real-time ... upgrade and backup, and USB hard disk, USB recorder and network backup.Multitask, local multi-screen real-time ... period. 4 Channel H.264 Car Mobile DVR Recorder