The block analyzer was doing lots of repeated, out-of-order blits to the
widget's canvas. To improve performance and reduce CPU usage, this has
been rewritten to generate the canvas contents using only a single buffer.
Cache thrashing has been greatly reduced by writing to memory only
sequentially and in one single write pass. Further, the raw format is
now guaranteed to be in a format efficient for Qt.
The results are visually identical to what they were previously, but
result in a CPU usage reduction between 2 and 6 percent depending on refresh
rate and Psychadelic Mode value. In particular, there used to be a ~3 percent
overhead for Psychadelic Mode, and this has been eliminated.
The specific details of the block analyzer and explanations for how it works
(and used to work) have been documented via fairly extensive comments
in blockanalyzer.cpp.
(Well, except Nyanalyzer and Rainbow dash because they are already colourful enough.)
I have added functionality for any 2D analyzer to change any part of its colour palatte with the frequency content of the music, in the same way that Moodbars do.
I find this gives the analyzer a sort of "third dimention".
This is built into Analyzer::Base, so all analyzers can use it and override it as they please. I have thus added support for Block, Boom, Turbine, Sonogram, and Bar, however Boom and Block seem to look the best in my opinion.
This is of course all optional and is toggled by a checkbox in the context menu for the analyzer, disabled by default.
I have not been able to measure any increase in CPU activity with this enabled, even at 60fps.
Block analyzer uses an internal variable m_step to determine how
long to hold a bar up. This is dependant on framerate, however it is
only set on creation or resize of the analyzer. This patch changes
this value whenever the framerate is changed, preventing the analyzer
from appearing wildly fast or extremely slow until a restart.
This patch prevents the framerate of all analyzers from
increasing beyond the framerate set in the interface at all times.
It however will allow the analyser to redraw as often as required
to prevent artifacting when the play scrubber is drawn in front.
Andrew Reading
John Maguire
santigl
Mark Furneaux
Krzysztof Sobiecki
John Maguire
Mark Furneaux
David Sansome