For #2371: Add regression test for SDP nack (#2487)

* explicitly enable nack, for firefox (#2373)

* For #2371: Add regression test for SDP nack

1. Refine API to change defaule decodes.
2. Add test for publish SDP nack.
3. Add test for play SDP nack.

Co-authored-by: Haibo Chen <495810242@qq.com>

trunk/conf/clion-ingest.conf

@@ -0,0 +1,53 @@
+
+listen              1935;
+max_connections     1000;
+daemon              off;
+srs_log_tank        console;
+
+http_server {
+    enabled         on;
+    listen          8080;
+    dir             ./objs/nginx/html;
+}
+
+http_api {
+    enabled         on;
+    listen          1985;
+}
+stats {
+    network         0;
+}
+rtc_server {
+    enabled on;
+    # Listen at udp://8000
+    listen 8000;
+    #
+    # The $CANDIDATE means fetch from env, if not configed, use * as default.
+    #
+    # The * means retrieving server IP automatically, from all network interfaces,
+    # @see https://github.com/ossrs/srs/wiki/v4_CN_RTCWiki#config-candidate
+    candidate $CANDIDATE;
+}
+
+vhost __defaultVhost__ {
+    rtc {
+        enabled     on;
+    }
+    http_remux {
+        enabled     on;
+        mount       [vhost]/[app]/[stream].flv;
+    }
+    ingest livestream {
+        enabled on;
+        input {
+            type    file;
+            url     ./doc/source.200kbps.768x320.flv;
+        }
+        ffmpeg      ./objs/ffmpeg/bin/ffmpeg;
+        engine {
+            enabled          off;
+            output          rtmp://127.0.0.1:[port]/live/livestream;
+        }
+    }
+}
+