secondly, the interface circuits which can perform the video format conversion is depicted . the circuits use the ma156 chip to decoder three types of standard analog format video, such as pal, ntsc and secam, and digitalize them and encode the digital signals into the ccir 656 standard format data 接口電路使用ma156芯片對(duì)標(biāo)準(zhǔn)清晰度模擬方式(pal制、ntsc制和secam制)視頻信號(hào)進(jìn)行解碼處理,被解碼的信號(hào)再經(jīng)模數(shù)轉(zhuǎn)換后被編碼為ccir656標(biāo)準(zhǔn)8位數(shù)據(jù)信號(hào),最后用wsc1115芯片進(jìn)行視頻格式轉(zhuǎn)換,并以模擬或數(shù)字方式輸出。