GNOME Bugzilla – Bug 640002
Lost 1. RTP packages from server after sending RTSP PLAY
Last modified: 2016-02-21 12:18:14 UTC
The server based on live555. The client: gst-launch rtspsrc location=rtsp://192.168.18.39:8554/22-16-M-short.wav ! decodebin2 ! filesink location=test.raw The trafic on the network looks like this: No. Time Source Destination Protocol Info 10 0.021750 192.168.17.72 192.168.18.39 RTSP SETUP rtsp://192.168.18.39:8554/22-16-M-short.wav/track1 RTSP/1.0 11 0.023679 192.168.18.39 192.168.17.72 RTSP Reply: RTSP/1.0 200 OK 12 0.061095 192.168.17.72 192.168.18.39 TCP 38021 > rtsp-alt [ACK] Seq=414 Ack=966 18 0.073468 192.168.17.72 192.168.18.39 RTSP PLAY rtsp://192.168.18.39:8554/22-16-M-short.wav RTSP/1.0 19 0.074308 192.168.18.39 192.168.17.72 RTP PT=DynamicRTP-Type-96, SSRC=0x80006A08, Seq=1495, Time=31077 20 0.074336 192.168.18.39 192.168.17.72 RTSP Reply: RTSP/1.0 200 OK 21 0.074705 192.168.17.72 192.168.18.39 TCP 38021 > rtsp-alt [ACK] Seq=555 Ack=1164 22 0.094731 192.168.18.39 192.168.17.72 RTP PT=DynamicRTP-Type-96, SSRC=0x80006A08, Seq=1496, Time=31079 The output in test.raw do not contain the 882 bytes data from the first RTP package. In another dump of network traffic, with the only difference that the first RTP package arrives after the RTSP OK, the output does contain the first 882 bytes of data. This behavior is consistence and seen in several sessions.
What are you trying to say? Is the first packet sometimes lost but not always? or is it always lost?
Created attachment 179784 [details] tcpdump capture file Dump of network trafic when running: gst-launch rtspsrc location=rtsp://192.168.18.39:8554/test.wav ! decodebin2 ! filesink location=test.raw
Created attachment 179785 [details] gst-launch debug info Dump of: gst-launch --gst-debug-no-color --gst-debug-level=5 rtspsrc location=rtsp://192.168.18.39:8554/test.wav ! decodebin2 ! filesink location=test.raw
The first package is always lost if it arrives before the "RTSP 200 OK" reply. Attached tcpdump and gst-launch debug info. From debug it seems that rtspsrc first starts receiving rtp packages after the "RTSP 200 OK" reply. Reported a bug on the live555 rtsp server mailing list about the RTP package sendt before the OK reply, and ended up with this response from the maintainer: http://lists.live555.com/pipermail/live-devel/2011-January/013044.html
I agree, GStreamer should not be dropping packets after it sends a PLAY command to the server.
Can't see where it would do that, it clearly starts the udp sources before sending the PLAY request.
mts, is this still an issue ? Based on wim's comments it shouldn't happen.
Closing, I assume it's fixed now. I'm sure people would notice if this happened consistently since it would mess up the first GOP. If it's still an issue for you with current versions, please re-open.