Decoding a h264 (High) stream with OpenCV's ffmpeg on Ubuntu - opencv

Question

I am working with a video stream from an ip camera on Ubuntu 14.04. Everything was going great with a camera that has these parameters (from FFMPEG):
Stream #0:0: Video: h264 (Main), yuv420p(progressive), 352x192, 29.97 tbr, 90k tbn, 180k tbc
But then i changed to a newer camera, which has these parameters:
Stream #0:0: Video: h264 (High), yuvj420p(pc, bt709, progressive), 1280x720, 25 fps, 25 tbr, 90k tbn, 50 tbc
My C++ program uses OpenCV3 to process the stream. By default OpenCV uses ffmpeg to decode and display the stream with function VideoCapture.
VideoCapture vc;
vc.open(input_stream);
while ((vc >> frame), !frame.empty()) {
*do work*
}
With the new camera stream i get errors like these (from ffmpeg):
[h264 # 0x7c6980] cabac decode of qscale diff failed at 41 38
[h264 # 0x7c6980] error while decoding MB 41 38, bytestream (3572)
[h264 # 0x7c6980] left block unavailable for requested intra mode at 0 44
[h264 # 0x7bc2c0] SEI type 25 truncated at 208
The image sometimes is glitched, sometimes completely frozen. However on vlc it plays perfectly. I installed the newest version (3.2.2) of ffmpeg player with
./configure --enable-gpl --enable-libx264
Now playing directly with ffplay (instead of launching from source code with OpenCV function VideoCapture), the stream plays better, but sometimes still displays warnings:
[NULL # 0x7f834c008c00] SEI type 25 size 896 truncated at 320=1/1
[h264 # 0x7f834c0d5d20] SEI type 25 size 896 truncated at 319=1/1
[rtsp # 0x7f834c0008c0] max delay reached. need to consume packet
[rtsp # 0x7f834c0008c0] RTP: missed 1 packets
[h264 # 0x7f834c094740] concealing 675 DC, 675 AC, 675 MV errors in P frame
Changing the camera hardware is not an option. The camera can be set to encode to h265 or mjpeg. When encoding to mjpeg it can output 5 fps, which is not enough. Decoding to a static video is not an option either, because i need to display real time results about the stream. Here is a list of API backends that can be used in function VideoCapture. Maybe i should switch to some other decoder and player?
From my research i conclude that i have these options:
Somehow get OpenCV to use libVlc instead of ffmpeg
One example of switching to vlc is here, but i don't understand it well enough to say if that is what i need. Or maybe i should be parsing the stream in code?
Use vlc to preprocess the stream, as suggested here.
This is probably slow, which again is bad for real time results.
Any suggestions and coments will be appreciated.

Answer 1

The errors are caused by packet loss since it uses RTP by default. You are seeing more errors now because you have switched to a higher bitrate input.
Append ?tcp to your input, eg. rtsp://*private*/media/video2?tcp in OpenCV's open function to force TCP, assuming it's supported by your hardware and/or usage scenario.

Answer 2

I have mostly solved this issue.
First i recompiled OpenCV with the newest version of ffmpeg manually installed on my device with the necessary settings.
I checked the stream with VLC tools > codec information to check if the stream has corrupted frames, which it didn't.
I lowered the stream resolution. This gave the biggest improvement.
The last error that i'm still left with is
[NULL # 0x7f834c008c00] SEI type 25 size 896 truncated at 320=1/1
[h264 # 0x7f834c0d5d20] SEI type 25 size 896 truncated at 319=1/1
but it doesn't visibly damage the frames. I have not resolved the stream freezing issue however, but it has something to do with my code, not the software. If i can help anyone with similar problems, feel free to ask additional info.

Answer 3

I have same problem after 4 days research finaly i solved the problem easy by this code:
for(;;) {
if(!vcap.read(image)) {
std::cout << "No frame" << std::endl;
cv::waitKey();
}
cv::imshow("Output Window", image);
if(cv::waitKey(1) >= 0) break;
}