Different size but equal quality?

[mai_hnf]

i'm korean drama fans.. I'd download few series but what bother me much is how two video with equal quality and resolution (video width,length) but they have different size of file... for example 250mb with 350mb or 350 mb with 700mb. How the conversion take place since the quality is equal for both sizes.......

[edDV]

i'm korean drama fans.. I'd download few series but what bother me much is how two video with equal quality and resolution (video width,length) but they have different size of file... for example 250mb with 350mb or 350 mb with 700mb. How the conversion take place since the quality is equal for both sizes.......

File size depends only on bit rate. Bit rate is independent of frame size although higher bit rates usually result in higher picture quality for a given frame size.

[olyteddy]

Compression is also affected by the amount of motion in the video. Still shots obviously would compress the best. At the same quality setting a car chase would use a higher bit rate.

[Abond]

They can differ also in duration (time).

[Midzuki]

How the conversion take place since the quality is equal for both sizes.......

Assuming the files are generated from the same source and
converted with the same program/codec, the respective ways
in which they are encoded make the difference.
Different configuration parameters may lead to the same
visual quality but at different file sizes; regarding DivX/XviD specifically,
multi-pass encoding may significantly reduce
file size without any apparent loss of quality.

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