user stream start is now sent only as reply to buffer length message

ngx_rtmp_receive.c

@@ -130,6 +130,8 @@ ngx_rtmp_user_message_handler(ngx_rtmp_session_t *s,
                 /* use =val as stream id && arg as buflen in msec*/
                 ngx_log_debug2(NGX_LOG_DEBUG_RTMP, c->log, 0,
                         "msid=%uD buflen: %uD (msec)", val, arg);
+
+                ngx_rtmp_send_user_stream_begin(s, val);
             }
             break;