???????Netflix?YouTube?TikTok?????????????HLS?DASH???????????????????????????????????????1.1 CDN?????????????????2015?50km/?????2023?20km/??AWS MediaConnect???????????????????"????"???????0.5%??1.2 ??????????? RTMP WebRTC SRT QUIC???? 3-10s 0.5-2s 1-3s 1-5s????? ? ? ?? ?????? ? E2EE AES-128 TLS1.31.3 ??????MPEG-TS????????????CMAF??????HLS?DASH?????