问题
I'm having difficulties in retrieving rtsp stream from a specific camera, because the rtp payload type the camera is providing is 35 (unassigned) and payload types accepted by the rtph264depay plugin are in range [96-127]. The result is that gstreamer displays ann error like:
<udpsrc0> error: Internal data flow error.
<udpsrc0> error: streaming task paused, reason not-linked (-1)
Other cameras that I have tested are working because they define a good payload type.
FFmpeg, MPlayer and other tools play the stream, although they may display a warning for the unknown type, for instance in Mplayer:
rtsp_session: unsupported RTSP server. Server type is 'unknown'
Is there any way in gstreamer to fake the payload type, ignore the mismatching property, force linking between the plugins or otherwise create a workaroud to my problem?
Pipeline I am using is:
gst-launcg-0.10 rtspsrc location="..." ! rtph264depay ! capsfilter caps="video/x-h264,width=1920,height=1080,framerate=(fraction)25/1" ! h264parse ! matroskamux ! filesink location="test.mkv"
回答1:
I figured it out and got it working. Posting an answer here in hope that it might benefit someone. There are multiple similar questions out there, but they lack proper answers.
Following does the trick:
GstElement* depay = gst_element_factory_make("rtph264depay", "video_demux");
assert(depay);
GstPad* depay_sink = gst_element_get_static_pad(depay, "sink");
GstCaps* depay_sink_caps = gst_caps_new_simple("application/x-rtp",
"media", G_TYPE_STRING, "video",
"encoding-name", G_TYPE_STRING, "H264",
NULL);
gst_pad_use_fixed_caps(depay_sink);
gst_pad_set_caps(depay_sink, depay_sink_caps);
gst_object_unref(depay_sink);
it overrides the rtph264depay plugin's sink pad caps to be less restrictive, now it accepts any payload type (and any clock-rate) as long as it is rtp and has H.264 encoding.
I don't think this is possible with gst-launch.
回答2:
There is a select-stream signal in rtspsrc module documented here http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-good-plugins/html/gst-plugins-good-plugins-rtspsrc.html#GstRTSPSrc-select-stream
it's a callback where you check the stream and if you return true, gstreamer will SETUP and PLAY the stream, if you return false it will ignore it, this should let you ignore the unsupported stream, in my case I'm having trouble with ONVIF metadata stream, it always tries to play it and there is no parser for it, I really wish gstreamer will just ignore the streams that can't play and work with what it has or at least a flag to toggle that behaviour.
来源：https://stackoverflow.com/questions/29250308/gstreamer-rtspsrc-and-payload-type