Good point re sizing. Will have a go and see how it does.
In a message dated 21/01/2007 09:58:38 GMT Standard Time,
I'd have to think about the exact details, but I totally agree with
the general idea that the spectral values should be cached, rather
than the resized spectrogram image. That should also make vertical
sizing of a spectrogram much faster, too.
On Jan 20, 2007, at 2:44 PM, MartynShaw@... wrote:
> I implemented the zooming in to the spectrum view but it is very
> slow and does not take advantage of the clever caching arrangement
> in WaveClip::GetSpectrogram. I have come up with a plan to
> increase the speed and wondered if anybody has an opinion on it
> before I set to work. I would:
> 1 Redefine viewHeight in SpecCache to be windowSize/2 and cache the
> spectral values, rather than the displayed values. This means I
> will always get a hit on the cache when zooming in and out
> vertically, and not redo all the ffts.
> 2 Remove all reference to max and min frequencies in the spectral
> 3 Move the summing-for-display section of ComputeSpectrum (lines
> 154-189) into TrackArtist::DrawClipSpectrum about line 1435. This
> would involve the max and min displayed frequencies. It would get
> used for horizontal scrolling however (it isn't currently) as the
> displayed greyscale values would not be cached, so would presumably
> slow this down.
> Is this a good idea?