It works to convert RTSP stream to flv stream, but I can't change resolution using below command
gst-launch-1.0 rtspsrc location=$RTSP_SOURCE latency=0 ! rtpbin ! rtph264depay ! h264parse ! avdec_h264 ! videoconvert ! videoscale ! video-x/raw,width=640,height=640 ! x264enc ! h264parse ! flvmux streamable=true ! rtmpsink location=$RTMP_SERVER
The pipeline shows an error saying that it could not link videoscale0 to x264enc0, neither element can handle caps video-x/raw, width=(int)640, height=(int)640
The media type should be
video/x-rawand notvideo-x/raw.