100% processor usage during playback

• Dec 16, 2012 - 14:19
S4 - Minor

I was curious about the new features of Musescore 2. So, I loaded the versions MuseScoreNightly-2012-12-11-1606-40e5376 and MuseScoreNightly-2012-12-12-2009-0b00926 to test a little bit. If I start playback of any score, then the processor usage rises from about 6% up to 100 % within the first 4 or 5 measures. At this point, music is chopped and working is impossible. When stopping the playback, the processor usage returns back to the prior 6%. If I start playback again at this point, the processor usage goes immediately to 100%.

Normally I use Musescore 1.2. There is no similar problem. If I start the playback with the same scores as above, there is no unusual increase of the processor usage.
In both cases, the internal Synthesizer and the default SoundFont TimGM6mb.sf2 is used.

My System:
Dell GX620 with Intel P4, 2.4GHz and 1.5 MB RAM
WIN XP professional with SP3


The issue is at every score, also at the default score ‘Promenade_Example.mscz’ supplied with all versions of Musescore.

I added a snapshot with the Task-Manager. The first peaks are when starting the nightly.bat. The middle block with 100% CPU usage is during playback.
I tried the MuseScoreNightly-2012-12-12-2009-0b00926 also at my Dell Notebook. It is an older D600 also with WIN XP prof SP3. The result is very similar to my GX260. (sorry GX260 is right). The CPU usage is also about 100% while playback is running, sometimes a little bit less. But the Music is not chopped at this Computer. That is the only difference.

Attachment Size
museScore.jpg 259.9 KB

I set reverb and chorus to min but without any change in CPU Usage at playback.

I tried out some things in the settings. In the I/O section I selected ‘Use JACK MIDI’ (I have no MIDI Instrument plugged on). Nevertheless the Playback CPU usage fall down to about 70% and it sounds good. But when closing and restarting Musescore there is no more sound available. If I open the settings again then Musescore crashes. At this point I can only delete the MuseScoreDevelopment.ini in the Document and Settings, or I edit the file and set the “useJackMidi” to false. Then I can help me again for one session with this wrong setting.

I found also that the same issue exists if I select a single note and use the arrow keys to go from note to note. After some measures the CPU Usage is at every single note 100% for some seconds.