ffmpeg can be used to debug RTSP streaming by using ffmpeg and ffplay.
Install ffmpeg and ffplay via brew install ffmpeg --with-ffplay.
- Create an RTSP stream
1.1. Raspberry Pi
ffmpeg -re -f video4linux2 -i /dev/video0 -map 0:0 -vcodec h264_omx -pix_fmt yuv420p -r 20 -f rawvideo -tune zerolatency -b:v 1500k -bufsize 1500k -payload_type 99 -ssrc 16132552 -f rtp -srtp_out_suite AES_CM_128_HMAC_SHA1_80 -srtp_out_params omz31e5SiZSneUySvSsIaFfu+NW2uWUl9+FHs3HD "srtp://192.168.0.14:58536?rtcpport=58536&localrtcpport=58536&pkt_size=1378"1.2. Mac
ffmpeg -re -f avfoundation -i "1" -map 0:0 -vcodec libx264 -pix_fmt yuv420p -r 20 -f rawvideo -tune zerolatency -b:v 1500k -bufsize 1500k -payload_type 99 -ssrc 16132552 -f rtp -srtp_out_suite AES_CM_128_HMAC_SHA1_80 -srtp_out_params omz31e5SiZSneUySvSsIaFfu+NW2uWUl9+FHs3HD "srtp://192.168.0.14:58536?rtcpport=58536&localrtcpport=58536&pkt_size=1378"- Create sdp file on receiver
v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 192.168.0.14
t=0 0
a=tool:libavformat 58.17.101
m=video 58536 RTP/AVP 99
b=AS:300
a=rtpmap:99 H264/90000
a=fmtp:99 packetization-mode=1
a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:omz31e5SiZSneUySvSsIaFfu+NW2uWUl9+FHs3HD
- Receive stream
ffplay -i <path-to-sdp-file> -protocol_whitelist file,udp,rtpffmpeg cannot set the bitrate on Raspberry Pi, we have to do it manually with v4l2-ctl --set-ctrl video_bitrate=300000.
ffmpeg only sends one H264 keyframe at the beginning of a RTP stream on the RPi because of https://video.stackexchange.com/a/21245 If we open the stream after it has been started using ffplay, we missed the keyframe and never get one – results in error: decode_slice_header error.
Therefore, we have to start ffplay before starting streaming.