I trying to reverse proxy a HLS stream (m3u8).

My nginx config :

server {
server_name proxy.domain.com;
resolver 8.8.8.8;

location / {
    set $backend $arg_url;
    proxy_pass http://$backend;
}

}

When I try to access the stream with http://proxy.domain.com/hls/live/stream.m3u8?url=stream.domain.com It gives me HTTP/1.1" 200 for the m3u8

"GET /hls/live/stream.m3u8?url=stream.domain.com HTTP/1.1" 200

But after it, it gives HTTP/1.1" 500 error for the .ts file !

"GET /hls/live/20190502T232455-05-14196689.ts HTTP/1.1" 500

When I check the error log file

[error] 32069#32069: *16 invalid URL prefix in "http://", client: MY IP, server: proxy.domain.com, request: "GET /hls/live/20190502T232455-05-14196689.ts HTTP/1.1", host: "proxy.domain.com", referrer: "http://player.url.com/?source=https://proxy.domain/hls/live/stream.m3u8?url=stream.domain.com"

I've tried proxy_pass http://$arg_url; but it's not working too.

Can someone help ?