Why do some calculators not take framerate into account?

[Tropican]

Recently I've noticed a very large amount of bitrate calculators do not take framerate into account, especially DVD bitrate calculators. Actually, I have yet to find a bitrate calculator for MPEG-2 that does.

Why is this?

[Ebobtron]

Maybe because within a group of encoded frames one frame could need 2 bits to describe it and the next one, may be 500kbits. Still pictures need less than hyperactive ones. I could be wrong.

[iNFO-DVD]

Why is this?What makes you think you need to? Calculators may look at the time or allow the user to input a time e.t.c. but the calculation may well, or only need to deal with the frames. If certain sizes are calculated on a frame basis then the FPS are irrelevent.

[Tropican]

If certain sizes are calculated on a frame basis then the FPS are irrelevent.

How could they be calculated on a frame basis if I'm not inputing the total number of frames in the source?

Or am I misunderstanding you?

[Doom9]

Bitrate = bits / seconds. No framerate in there unless you want to use number of frames instead of seconds.
Then the formula becomes bits / (fps * number of frames of the source).. but most people are more familiar with the above notation and don't even know how many frames their source has.

[foxyshadis]

The calculator relies on the encoder to correct for any framing overhead in its rate control. If the encoder doesn't, well, it's junk. Of course TS has a much higher framing overhead than ES, so if you mux it in after the fact without having taken that into consideration, there could be problems. But I thought that PS's framing overhead was very low compared to TS, near ES, so it doesn't much matter. Do you know different?

[Tropican]

Bitrate = bits / seconds. No framerate in there unless you want to use number of frames instead of seconds.
Then the formula becomes bits / (fps * number of frames of the source).. but most people are more familiar with the above notation and don't even know how many frames their source has.

Funny, I was actually only familiar with the bits / (fps * number of frames of the source) notation. Thanks for explaining it Doom9.

Of course TS has a much higher framing overhead than ES, so if you mux it in after the fact without having taken that into consideration, there could be problems. But I thought that PS's framing overhead was very low compared to TS, near ES, so it doesn't much matter. Do you know different?

I know you probably weren't asking me, but it does indeed go ES<PS<TS sorted by overhead AFAIK. Most calculators do a TS overhead for obvious reasons.