dash流，如果seek拉取指定的远程m4s文件

[Lee6804]

HTTP error 404 Not Found Failed to open fragment of playlist 0 DASH request for url 'xxxxxx.m4s', offset 0, playlist 0 Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy' tcp did open uri = xxx, ip = the user-agent option is deprecated, please use user_agent option request: GET xxxxx.m4s HTTP/1.1

User-Agent: ijkplayer

Accept: /

Range: bytes=0-

Connection: close

Host: uat-video-playback.ctwalidev.tcljd.cn

Icy-MetaData: 1

播放一段非完整的dash流时，m4s文件会按顺序依次加载，seek操作没有响应，无法seek拉取指定时间的m4s文件，