video – h264 from rtpdump using ffmpeg

There is a video call, that I had tcpdumped by wireshark. After that I’ve got rtpdump file of the h264-videostream. And I try to make mp4 file using ffmpeg

I’ve prepared an sdp file as below

v=0
c=IN IP4 127.0.0.1
m=video 4646 RTP/AVP 96
a=rtpmap:96 H264/90000

I send rtpdump by rtpplay to local port 4646, trying to make mp4 file using command
ffmpeg -protocol_whitelist file,udp,rtp -i sdp.sdp video.mkv
Unfortunately I get only this

  libavutil      57.  0.100 / 57.  0.100
  libavcodec     59.  1.100 / 59.  1.100
  libavformat    59.  2.100 / 59.  2.100
  libavdevice    59.  0.100 / 59.  0.100
  libavfilter     8.  0.101 /  8.  0.101
  libswscale      6.  0.100 /  6.  0.100
  libswresample   4.  0.100 /  4.  0.100
  libpostproc    56.  0.100 / 56.  0.100
[sdp @ 000001dcab0aaa00] Could not find codec parameters for stream 0 (Video: h264, none): unspecified size
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
Input #0, sdp, from 'sdp.sdp':
  Duration: N/A, bitrate: N/A
  Stream #0:0: Video: h264, none, 90k tbr, 90k tbn
Output #0, matroska, to 'protei.mkv':
Output file #0 does not contain any stream

May be ffmpeg can’t detect h264 codec because of DynamicRTP? If I capture the stream, generated by rtpplay, there is a Payload type: DynamicRTP-Type-126 (126)
local_capture