user6074: I have been working on video conversion. So, to find out video parameters I used ffprobe. However, when I run the command on an mp4 video file, I observe this:
 
Total bitrate: 3547 Kb/s 
Video bitrate: 3512 Kb/s
Audio bitrate: 32 Kb/s
Why total bitrate is 3 Kb/s more than the sum of audio and video bitrates?

user3908: I don't know for sure, but the total bitrate may be calculated as size / duration, which would include the container overhead. IOW the actual bit rate would be the sum of the two stream rates, with the container overhead shown as distributed over the entire length.

user2836: There are a few possibilities.  MP4 is a container format and can contain more than just audio and video streams.  While not all necessarily supported by MP4 specifically, container formats can contain things like sub-titles, sync data, chapter markers, meta-data, etc.  They can also potentially contain more than one audio or video stream.
From the level of detail provided, it isn't really possible to tell exactly what is taking the extra space, it may just be overhead of the format itself or it could be some additional data stream that is stored within the container.

6074: <p>I have been working on video conversion. So, to find out video parameters I used ffprobe. However, when I run the command on an mp4 video file, I observe this:</p>

<p><img src="https://i.stack.imgur.com/GHt7s.jpg" alt="enter image description here"> </p>

<p>Total bitrate: 3547 Kb/s 
Video bitrate: 3512 Kb/s
Audio bitrate: 32 Kb/s</p>

<p>Why total bitrate is 3 Kb/s more than the sum of audio and video bitrates?</p>
 3908: <p>I don't know for sure, but the total bitrate may be calculated as size / duration, which would include the container overhead. IOW the actual bit rate would be the sum of the two stream rates, with the container overhead shown as distributed over the entire length.</p>
 2836: <p>There are a few possibilities.  MP4 is a container format and can contain more than just audio and video streams.  While not all necessarily supported by MP4 specifically, container formats can contain things like sub-titles, sync data, chapter markers, meta-data, etc.  They can also potentially contain more than one audio or video stream.</p>

<p>From the level of detail provided, it isn't really possible to tell exactly what is taking the extra space, it may just be overhead of the format itself or it could be some additional data stream that is stored within the container.</p>
