How do I launch deepstream sample application?

Documentation lacks clear instruction on how to launch sample applications. There are several applications and several config files, so there are many combinations how you can launch them. This number gets enormous if you try to launch from different folders. I tried this one:

stiv@gaidar:/opt/nvidia/deepstream/deepstream-4.0/samples/models/Primary_Detector/a$ deepstream-test1-app /opt/nvidia/deepstream/deepstream-4.0/samples/streams/sample_720p.mp4

I had to create subfolder a, otherwise it doesn’t find caffe model with hardcoded path. I get these lines of output:

Creating LL OSD context new
0:00:00.321174382 16565 0x558fe0c20580 INFO                 nvinfer gstnvinfer.cpp:519:gst_nvinfer_logger:<primary-nvinference-engine> NvDsInferContext[UID 1]:initialize(): Trying to create engine from model files
0:00:08.034524106 16565 0x558fe0c20580 INFO                 nvinfer gstnvinfer.cpp:519:gst_nvinfer_logger:<primary-nvinference-engine> NvDsInferContext[UID 1]:generateTRTModel(): Storing the serialized cuda engine to file at /opt/nvidia/deepstream/deepstream-4.0/samples/models/Primary_Detector/resnet10.caffemodel_b1_int8.engine
Running...

But nothing is shown on display. Is it supposed to show nothing? This is on Ubuntu AMDx64. Same happens on Jetson Nano, but with another samples after resolving runtime errors. Can anyone provide instruction how to run any sample which shows anything on the screen?

Could you check the deepstream-test1 README first? it will receive h264 stream as input.