What could change the fps when copying frames from mp4 file to mp4 without reencoding?

Question

I try to copy video from in.mp4 to out.mp4 without reincoding. I'm using the code example suggested by pogorskiy here. The copy process success, but the video is played very fast. I checked the fps of both files with MediaInfo. The fps of "in.mp4" is 25 fps and "out.mp4" it 533fps. I don't understand what changing the fps to 533 if I construct outStream from inStream?

I hope I explained myself correctly.

Answer 1

The problem was in PTS and DTS values. They must be set correctly.

The detailed answer is here