0xtob’s coding blog

I just learned Fast Fourier Transform at school and I thought it would be a good exercise to implement it for the DS. The result is this little app:

DS Spectrum Analyzer

It records sound with the mic, displays the signal on the bottom screen and the spectrum that was calculated with FFT on the top screen. It also calculates an estimate of the main frequency, but that is not very accurate yet.

I haven’t run extensive benchmarks yet, but it can definitely keep up nicely at the current recording frequency, which is 11025 Hz. Also, I don’t yet know what I might use this for, but it’ll certainly come in handy at some point.

Update: I updated the app to use overlapping windows, so it now runs at twice the framerate!

For testing on the GBAMP I like using a Wifi downloader like DSFTP. But it became kind of annoying to navigate to DSFTP with Moonshell every time I wanted to test my app. Setting DSFTP as boot application was bad too, because I tended to forget to switch the boot app back to Moonshell, and so I couldn’t use DS homebrew on the road.

A quick (as in one hour of coding) solution I came up with is the GBAMP DevLauncher which works as follows: If you hold Y at boot time, you enter a menu in which you can select an application which is booted automatically when you turn on the DS. So you can easily change the boot application of the DS at the cost of a slightly increased boot time (about 1 second).

I don’t know if this is useful to anyone but myself, but if you want to try it, get it here.

It turns out that sending the MIDI message (0, 0, 0) to some applications causes them to stop working. This, unfortunately, is the keep-alive message that the DS sends to the server every three seconds. So I patched the three servers to not forward this message any more.

Updating, re-packaging and uploading all thee servers takes quite some time, so I hope they are now bug-free :-)

The updated server is available from the DSMIDIWiFi homepage.