WebRTC: 推RTC拉RTMP，VLC首屏很久2分钟左右

[bbhxwl]

Please description your issue here(描述你遇到了什么问题) docker运行的， webrtc推，vlc拉，一直加载中要很久，可能要2分钟，才会出来。正常么？

1. SRS Version(版本): 4.0.252

2. SRS Log(日志):

xxxxxxxxxxxx

1. SRS Config(配置):

# docker config for srs.
# @see full.conf for detail config.

listen              1935;
max_connections     1000;
# For docker, please use docker logs to manage the logs of SRS.
# See https://docs.docker.com/config/containers/logging/
srs_log_tank        console;
daemon              off;
http_api {
    enabled         on;
    listen          1985;
}
http_server {
    enabled         on;
    listen          8080;
    dir             ./objs/nginx/html;
}
rtc_server {
    enabled on;
    listen 8000;
    # @see https://github.com/ossrs/srs/wiki/v4_CN_WebRTC#config-candidate
    candidate $CANDIDATE;
}
vhost __defaultVhost__ {
    hls {
        enabled         on;
    }
    http_remux {
        enabled     on;
        mount       [vhost]/[app]/[stream].flv;
    }
 http_hooks { 
        enabled          on;
        on_connect       http://***:5000/api/StreamingApi/on_connect;
        #on_close       http://***:5000/api/StreamingApi/on_close;
        on_publish       http://***:5000/api/StreamingApi/on_publish;
        #on_unpublish     http://***:5000/api/StreamingApi/on_unpublish;
        #on_play          http://***:5000/api/StreamingApi/on_play;        
       #on_stop          http://***:5000/api/StreamingApi/on_stop;                                 
           }
    rtc {
        enabled     on;
        # @see https://github.com/ossrs/srs/wiki/v4_CN_WebRTC#rtmp-to-rtc
        rtmp_to_rtc on;
        # @see https://github.com/ossrs/srs/wiki/v4_CN_WebRTC#rtc-to-rtmp
        rtc_to_rtmp on;
    }
}

Replay(重现)

Please describe how to replay the bug? (重现Bug的步骤)

1. xxxxxx
2. xxxxxx
3. xxxxxx

Expect(期望行为)

Please describe your expectation(描述你期望发生的事情)

[winlinvip]

WebRTC was not originally designed for live streaming, so there will be many issues if you use WebRTC for live streaming or convert it into a live streaming protocol.

However, there should be room for optimization.

TRANS_BY_GPT3