Bitrates don't add up (literally)

[AdrianK]

If I understand correctly, the total bitrate should be the sum of the bitrates of all streams, in this case 3820kb/s in total (from 3500+160+80+80). However, the total bitrate is shown as 4142kb/s, so there's a 322kb/s unaccounted for.

Or is 3500kb/s just the target bitrate, so the resultant bitrate could be higher or lower than the target?

Here's a full Media Info report, if that helps.

 

[roidy]

In your MediaInfo report under video stream 1 there is a line that says:-

Video Stream BitRate Mode.........................VBR

VBR means Varible Bit Rate, meaning the bitrate changes depending on the video complexity, for example really dark or black scenes will have a very low bitrate and really detailed scenes will have a very high bitrate. So the given bit rate figures are just averages. The same is true with the audio.

 

[AdrianK]

But if they're averages, it shouldn't matter, because you've already accounted for the fact that the bitrate fluctuates by averaging it...?

 

[roidy]

I see what your saying and to be honest I really don't know. The only way I can get them to add up is by counting each audio channel individually.

Video stream          -  3500
Audio stream 1 Left   -  160
Audio stream 1 Right  -  160
Audio stream 2 Left   -  82.3
Audio stream 2 Right  -  82.3
Audio stream 3 Left   -  82.3
Audio stream 3 Right  -  82.3

Total                 - 4149.2

Still not exact but a lot closer.

 

[AdrianK]

That's really interesting. Thanks for looking in to it