Aspirin for net

voice compression video compression voice compresssion: G.711 (PSTN, 64kbps) -> G.729 (8kbps) video compression: Mpeg2: dvd quality (1.5M~10Mbps) mpeg4: low quality (28.8kbps ~ 400kbps) G.729 ; default well-known voice codec, skype, cisco etc... cisco ip phone assists G.711, G729a VAD(Voice Activity Detection) or Silence Suppression CNG(Comport Noise Generation)

PCM: Pulse Code Modulation , G.711, DS0 (base band) analog sampling per 125ms, 8bit info in 1 sec, 8bit * 8000 = 64,000 bits, 64Kbps ( 1ms = 1/1,000,000 sec, 125ms = 125* 1/1,000,000 sec = 1/8,000 sec) ICND Office Exam Cert~Guide *modem *DSL *Cable