Re: [question/testing] SoundFileView improvements

I figured out how to preserve cache in SHORTs and set the scaling
dynamically when reading the file, reworked everything... and got the same
(slower) result as when I was working with floats.
Turns out I was building in "debug"....

So after switching to RelWithDebInfo, I'm getting very similar performance
when using cache in SHORTs vs FLOATs. In this case do you think it is
reasonable to just switch to floats?

Thanks,
Marcin

On Fri, Apr 6, 2018 at 1:53 PM, Marcin Pączkowski <[email protected]> wrote:

> Thanks for the suggestions, Scott.
>
> In further working on this, I came to realize that:
> - we can stick to short_int, since:
> - we can't set the data after loading a soundfile, so setting min/max
> values from the soundfile would fix representation of float soundfiles
> - I'd add maxValue parameter to the allocate and setData methods, to
> provide that control to the user when plotting data from the language
>
>
>> 1. p.drawLine( x + i, min, x + i, max );
>>     p.drawLine( x + i, minRMS[i], x + i, maxRMS[i] );
>> These might be faster if they were a 1px wide fillRect.
>>
> Maybe I'll try these later in my branch.
>
> 2. compositionMode of the pen should be QPainter::CompositionMode_Source
>>
> Will try...
>
>
>> 3. p.setClipping(true); p.setClipRect( x, -halfChH, x+width, chHeight );
>> I believe it would be cheaper to guarantee the ranges of our values
>> either when we calculate in displayData, or inline in our inner loop.
>>
> Yeah, I'll remove this clipping. I'll need to ensure data range in
> displayData anyway and my whole point is to be able to draw values outside
> this range.
>
>
>> 4. Drawing vertical lines is bad for cache coherence and eliminates
>> possibilities for vectorization. It MIGHT be worth experimenting with
>> rotating the pixmap 90 degrees and drawing that way (so we have horizontal
>> scanlines), and then rotating back to the correct orientation when we do
>> drawPixmap, in hopes that Qt has either optimized the 90 degree rotation
>> case or vectorized horizontal line drawing.
>>
> I'm not sure I'll get to trying this... but it's an interesting concept.
>
> Anyway, I'll keep working on this and will probably submit a PR once it's
> in a working state.
>
> Marcin
>