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« on: September 24, 2010, 11:09:14 »
The new analysis mode is a nice feature, but has to be used with caution:
VBR files are rated totally false, the bitrate is taken from the first frame(s) where it is typically very low. Consequently the duration is calculated much too high (total size by first frame size).
Reading of further frames seems to take into account the bitrate in frame header, otherwise complete rubbish would appear.
I would advise to ether correct ratings for VBR to average bitrate or drop rating (at the moment) for VBR at all.
In frequency analysis I found another problem: I got a rating of 100% for a file sampled at 44100 Hz with a max. frequency of 22050. Files should never contain frequencies up to the Nyquist frequency (half the sample rate), because that leads to annoying alias frequencies. That should lead to drastic reduction in quality rating. For the file in question I found no perceptible degradation, so the max. frequency value may be an analysis flaw.
Again: Be reluctant with analysis ratings, but with some caution it's a valuable feature. Calculating quality measures is a demanding task.