ffmpeg -loglevel verbose -stimeout 30000 -probesize 6000M -probesize 6000M -rtsp_transport tcp -i rtsp://someurl -r 5 -an -s 352x288 -q:v 8 -updatefirst 1 -y c:\tmp\test.jpg

ffmpeg version N-80011-gaf3e944 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 5.3.0 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-lib
modplug --enable-libmfx --enable-libmp3lame --enable-libopencore-amrnb --enable-
libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enabl
e-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable
-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --ena
ble-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx
264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable
-lzma --enable-decklink --enable-zlib
  libavutil      55. 24.100 / 55. 24.100
  libavcodec     57. 42.100 / 57. 42.100
  libavformat    57. 36.100 / 57. 36.100
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 45.100 /  6. 45.100
  libswscale      4.  1.100 /  4.  1.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
[rtsp @ 0003c100] SDP:
v=0
o=- 429332836659660 1 IN IP4 someurl
s=Session of second stream
i=Second Codec Stream
t=0 0
a=tool:LIVE555 Streaming Media v2007.08.03
a=type:broadcast
a=control:*
a=range:npt=0-
a=x-qt-text-nam:Session of second stream
a=x-qt-text-inf:Second Codec Stream
m=video 0 RTP/AVP 96
c=IN IP4 0.0.0.0
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1;profile-level-id=428028;sprop-parameter-sets=Z0KA
KNoFglE=,aM48gA==
a=control:track1

[rtsp @ 0003c100] setting jitter buffer size to 0
[rtsp @ 0003c100] Could not find codec parameters for stream 0 (Video: h264, 1 r
eference frame, none): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, rtsp, from 'rtsp://someurl':
  Metadata:
    title           : Session of second stream
    comment         : Second Codec Stream
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: h264, 1 reference frame, none, 90k tbr, 90k tbn
Output #0, image2, to 'c:\tmp\test.jpg':
Output file #0 does not contain any stream