补课

DVB-S2         MPEG        SCART        CA        CI        HD        Letterbox        Pan and scan

http://www.elecfans.com/article/88/130/167/2009/2009090288851.html

http://www.ent.eet-china.com/ART_8800421658_2700003_TA_dc6df7bf.HTM

http://tech.c114.net/167/a478807-2.html

ASPECT: set the video aspect ratio
Pin 8, the switch signal pin, carries a DC voltage from the source that indicates the type of video present.
0 V–2 V means no signal, or internal bypass
4.5 V–7 V (nominal 6 V) means a widescreen (16:9) signal
9.5 V–12 V (nominal 12 V) means a normal (4:3) signal

TV_FB: set the video format: CVBS /RGB
Pin 16, the blanking signal pin, carries a signal from the source that indicates that the signal is either RGB or composite.
0 V–0.4 V means composite.
1 V–3 V (nominal 1 V) means RGB only.