... SpecificationsModelDVR8504HSystemMain ProcessorHigh performance embedded microprocessorOperating SystemEmbedded LINUXSystem ResourcesPentaplex function: live, recording, playback, backup & ... 288/352×240)Encoding SpeedMain Stream: full 4ch D1 (25/30fps)/4ch@ ... , Previous file, Next camera, Previous camera, Full screen, Repeat, Shuffle, Backup selection, Digital ... preview ,DVD-RW function, alarm function