[FFmpeg-user] ffmpeg VSTARCAM RTSP only in UDP

[cagnulein]

Hi guys, it's my first topic here, so please be nice :D
I have a IPCAM from VSTARCAM that only accepts rtsp via udp. On android
works fine with the app ONVIFER but on linux or macos and ffmpeg i've got
always this problem:

$ ffmpeg -v trace -rtsp_transport udp -i
rtsp://admin:XXXXXX@192.168.0.37:10554/udp/av0_0 -vframes 1 -timeout
10 /tmp/ipcam-contatore-acqua.jpg

ffmpeg version 4.1.4-1~deb10u1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 8 (Raspbian 8.3.0-6+rpi1)
  configuration: --prefix=/usr --extra-version='1~deb10u1'
--toolchain=hardened --libdir=/usr/lib/arm-linux-gnueabihf
--incdir=/usr/include/arm-linux-gnueabihf --arch=arm --enable-gpl
--disable-stripping --enable-avresample --disable-filter=resample
--enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom
--enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca
--enable-libcdio --enable-libcodec2 --enable-libflite
--enable-libfontconfig --enable-libfreetype --enable-libfribidi
--enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame
--enable-libmysofa --enable-libopenjpeg --enable-libopenmpt
--enable-libopus --enable-libpulse --enable-librsvg
--enable-librubberband --enable-libshine --enable-libsnappy
--enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora
--enable-libtwolame --enable-libvidstab --enable-libvorbis
--enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265
--enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi
--enable-lv2 --enable-omx --enable-openal --enable-opengl
--enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883
--enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
Splitting the commandline.
Reading option '-v' ... matched as option 'v' (set logging level) with
argument 'trace'.
Reading option '-rtsp_transport' ... matched as AVOption
'rtsp_transport' with argument 'udp'.
Reading option '-i' ... matched as input url with argument
'rtsp://admin:XXXXXX@192.168.0.37:10554/udp/av0_0'.
Reading option '-vframes' ... matched as option 'vframes' (set the
number of video frames to output) with argument '1'.
Reading option '-timeout' ... matched as AVOption 'timeout' with argument '10'.
Reading option '/tmp/ipcam-contatore-acqua.jpg' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option v (set logging level) with argument trace.
Successfully parsed a group of options.
Parsing a group of options: input url
rtsp://admin:XXXXXX@192.168.0.37:10554/udp/av0_0.
Successfully parsed a group of options.
Opening an input file: rtsp://admin:XXXXXX@192.168.0.37:10554/udp/av0_0.
Probing rtsp score:100 size:0
[tcp @ 0x1a73600] No default whitelist set
[tcp @ 0x1a73600] Original list of addresses:
[tcp @ 0x1a73600] Address 192.168.0.37 port 10554
[tcp @ 0x1a73600] Interleaved list of addresses:
[tcp @ 0x1a73600] Address 192.168.0.37 port 10554
[tcp @ 0x1a73600] Starting connection attempt to 192.168.0.37 port 10554
[tcp @ 0x1a73600] Connection attempt to 192.168.0.37 port 10554
failed: Connection refused
[tcp @ 0x1a73600] Connection to tcp://192.168.0.37:10554?timeout=0
failed: Connection refused
rtsp://admin:XXXXX@192.168.0.37:10554/udp/av0_0: Connection refused

Why ffmpeg tries always to run in tcp while i'm asking to use udp?

Thanks

Roberto