MPEG2 Settings

[jeffh123]

Does anyone know a formula for calculating the MPEG2 file size derived from -

a) Resolution i.e. image height and width
b) The Video bitrate
c) The audio bitrate
d) The quality
e) The length of the captured image in seconds.

I've looked at the material under the calculator list on this forum and somehow resolution does not appear. I also have a setting on my video capture software which allows for a quality setting, that certainly does not appear in any of these tools.

[FT Shark]

That is because resolution doesn't have much of an impact to the overall file size.

[FOO]

(b + c) * e = total bits

[bugster]

That is because resolution doesn't have much of an impact to the overall file size.

The resolution doesn't have ANY impact on the overall file size.

The only things that affect the size of an mpeg file are:-

1) Bitrate
2) Playing time.

Nothing else matters.

Now, how a particular piece of software allows you to adjust the bitrate varies significantly. Take TmpGenc as an example.

CBR = Constant bitrate. Great, we can calculate the filesize accuratley
VBR - 2-pass. Using the AVERAGE bitrate value we can calculate the final filesize accuratley
CQ - a form of 1 pass Variable bitrate, but we have no accurate control over the average bitrate to be used, just the CQ value, which is some form of 'quality' level.

I also have a setting on my video capture software which allows for a quality setting, that certainly does not appear in any of these tools.

The 'quality' setting in your capture software may well be something similiar to the CQ mode of TmpGenc. If you want to accuratley predict filesize, use CBR or multi-pass VBR encoding where you can set the average. If you are capturing straight to mpeg, you may want to consider changing your methods/software.