I created 26,640 positive images from a collection of 20 object images and 1350 negative images. I ran opencv_create samples 20 times, each time using the same 1350 negative images. The result was a collection of 26,640 positive images and 20 info.lst files. I concatenated all of the the .lst files into a single list file called info-t.lst, it contains a description line for all 26,640 unique positive images in the pos directory.
When I attempt to create the vector file from the 26,640 images and the info-t.lst file, only 1000 samples are created. Is num = 1000 the maximum? I can't find any documentation to indicate that is the case. Here is the command line I am using to create the vector file.
opencv_createsamples -info pos/info-t.lst -w 30 -h 40 -vec -num 26640 positives.vec