怎么处理相对路径m3u8格式下载？

m3u8格式下载，相对路径列表经过地址转换后会返回可直接下载的全路径,不需要再去拼接

例：原始m3u8列表地址

#EXT-X-KEY:METHOD=AES-128,URI="/mykey.key",IV=0x000000
#EXTINF:5.051444,
xxx/output0.ts
#EXTINF:5.005011,
xxx/output1.ts

pcdn下载后的m3u8地址

#EXT-X-KEY:METHOD=AES-128,URI="http://cdn.xxx.com/mykey.key",IV=0x000000
#EXTINF:5.051444,
http://127.0.0.1:8908/pcdn/s/100/1/aHR0cDov/cdn.xxx.com/201701/a/xxx/output0.ts
#EXTINF:5.005011,
http://127.0.0.1:8908/pcdn/s/100/2/aHR0cDov/cdn.pcdnv.xxxx.net/201701/a/xxx/output1.ts