rtsp failure: nonmatching transport

[ksmuthucv]

System information (version)

• OpenCV => 4.1.1
• Operating System / Platform => Windows 64 Bit
• Compiler => Visual Studio 2017

Detailed description

I couldn't not make rtsp url loaded/displayed with latest codebase via ffmpeg. it gives an error related to transport protocol i.e. Nonmatching transport in server reply. now in the latest code open-cv uses pre-built binaries (opencv_videoio_ffmpeg411_64.dll) to handle rtsp streaming, couldn't debug that part closer. Please note that this rtsp url is streamed propertly in vlc player (latest) && in ffplay.exe via command line arguments.

latest ffmpeg sdk plays this rtsp url without issue and any delay.

Code

std::string nwindow = "OpenCv", address = "rtsp://";

//this below line didn't make any difference either
_putenv_s("OPENCV_FFMPEG_CAPTURE_OPTIONS", "rtsp_transport;udp");

cv::Mat frame;
cv::VideoCapture cap;
bool status = cap.open(address);
while (status && true)
{
cap >> frame;
//(display the frame and proceed)
}

Error

[ INFO:0] global C:\Files\Library\opencv\sources\modules\videoio\src\videoio_registry.cpp (187) cv::`anonymous-namespace'::VideoBackendRegistry::VideoBackendRegistry VIDEOIO: Enabled backends(7, sorted by priority): FFMPEG(1000); GSTREAMER(990); INTEL_MFX(980); MSMF(970); DSHOW(960); CV_IMAGES(950); CV_MJPEG(940)

[ INFO:0] global C:\Files\Library\opencv\sources\modules\videoio\src\backend_plugin.cpp (340) cv::impl::getPluginCandidates Found 2 plugin(s) for FFMPEG

[ INFO:0] global C:\Files\Library\opencv\sources\modules\videoio\src\backend_plugin.cpp (172) cv::impl::DynamicLib::libraryLoad load C:\Files\Work\Samples\opencv.va.pg\x64\Debug\opencv_videoio_ffmpeg411_64.dll => OK

[ INFO:0] global C:\Files\Library\opencv\sources\modules\videoio\src\backend_plugin.cpp (220) cv::impl::PluginBackend::PluginBackend Video I/O: loaded plugin 'FFmpeg OpenCV Video I/O plugin'
[rtsp @ 0000022b502b75c0] Nonmatching transport in server reply

[ INFO:0] global C:\Files\Library\opencv\sources\modules\videoio\src\backend_plugin.cpp (340) cv::impl::getPluginCandidates Found 2 plugin(s) for GSTREAMER

Can you please help?

[jsxyhelu]

have you tired another rtsp sources?

[ksmuthucv]

i had tried bunny rtsp and it worked. the one i had mentioned above is ip camera url. it fails while using ffmpeg mechanism from opencv. but the source/sdk of ffmpeg is playing it without delay. is there a way/option to configure protocol precedence (i.e. setting it in avdictionary of ffmpeg) from opencv? as i mentioned using below line also didn't have any impact.

_putenv_s("OPENCV_FFMPEG_CAPTURE_OPTIONS", "rtsp_transport;udp");