VideoReader framerate is not matching total number of frames

I use VideoReader command to find the frames per second (FPS) for a recorded video

Obj=VideoReader('Movie1');

Here are some of the data of interest I get

Obj.Duration=120.9370 % total video duration
Obj.FrameRate=29.4492 % Frame rate Meta data
Obj.NumberOfFrames=3552 % Total frames

The problem is that the

Obj.FrameRate=29.4492 is not equal to 

Obj.NumberOfFrames/Obj.Duration=29.3707.

This difference is very significant for my problem,so

1- Which value is more reliable?

2- What is the reason behind this inconsistency?

Many Thanks,

Answer 1

[Tommaso Lucarelli]

Hello Hazem,

I'm working on a project and I have found exactly the same issue, I'm facing this problem and I don't know how to find a solution.

Did you find a way to fix it at the end? This difference is very significant for my problem.

Thanks a lot, have a nice evening,

Tommaso

Answer 2

[Kris Fedorenko]

I believe "FrameRate" is not guaranteed to be constant throughout the playback. This should give you a more accurate value:

vobj = VideoReader('mymovie.avi');
numFrames =vobj.NumberOfFrames
vobj = VideoReader('mymovie.avi'); % need to re-instantiate after computing NumberOfFrames

[Walter Roberson]

NumberOfFrames is estimated from the known duration and initial frame rate, and is known to have round-off problems even for fixed framerate images.