Saturday, August 27, 2011

Presenting VMPK for Nokia N950

I've been playing with my new and sexy Nokia N950 developer device, and here is the fruit: a newborn VMPK. I've just released a beta for testing, usable but not yet optimized. Please, try it. Your feedback will be appreciated.

Download VMPK & FluidSynth for N950 from

I've learned two lessons from the Symbian port of VMPK published at Nokia's OVI Store: people expect that if a program looks like a piano, it should sound like a piano. It doesn't matter if the product description says that it doesn't produce any sound by itself. Dozens of comments in OVI Store page confirm that there is no hope that users read the description before downloading a program.

When I was doing some research for the Symbian port, I've discovered that creating sound always used very large audio buffers, no matter the method, producing about one second of latency or more. This is unacceptable for a musical instrument emulation, so network MIDI was the only available option. On the other hand, the Nokia N9xx uses Linux, including ALSA and PulseAudio among other usual infrastructure, so the latency is not a problem and FluidSynth is a perfectly sound complementary addition to VMPK.

Second lesson: an user interface that fits well in the desktop version of the program is barely usable on the mobile phone form factor. The solution is to create a new user interface using QML, the new declarative language for Qt user interfaces. The piano keyboard widget was already built around the Qt Graphics View Framework, so it only required to be wrapped as a QDeclarativeItem subclass and it was readily available as a QML object, to be combined with the Qt Quick Components for Meego library to build the new user interface. Here are some screenshots.

Main page, common controls are shown.

Main menu, note names option activated.

Preferences page.

About page.