|
Ableton Live is one good example of how GUI programming and improper priorization can mess with audio performance. For some reasons Live's GUI drawing often supersedes audio computing even though the thead priorities seem to be ok. One pronounced problem is moving the mouse over track-clips in Arrangement View. Turning Live to "Realtime" fixes the problems instantly.
The first 9 or 10 versions of Live 7 were unusable on Vista if you turned Aero *off* (Ableton refused to even acknowledge any problem). Whatever GUI drawing routines were used they caused such high CPU load and havoc behavior that you could not even playback a single audio clip without dropouts when using small audio buffers. Turning on Aero instantly fixed the CPU load issue because those GUI drawing routines were obviously handled by Aero/DWM/GPU then. So things are seemingly a bit more complicated.
Then Ableton changed something (without telling anyone about the issue or the fix) and now it doesn't matter much whether you are using Aero or not, the CPU load stays the same. The main problem remains with priorities now.
One thing I learned about Aero is that the whole off-screen composition thing of summing all single applications' output, doing some optimization and putting it out all at once not only can save CPU load but also fix some plugin drawing issues. Desktop composition is kind of a filter, an endpoint for all GUI output that predigests everything to uniform pieces before turning it over to the graphic-card driver.
|