Add spectrum analyzer demo app

This application is a demo which uses the QtMultimedia APIs to
capture and play back PCM audio.  While either recording or playback
is ongoing, the application performs real-time level and frequency
spectrum analysis.

Reviewed-by: Alessandro Portale

1 files changed, 34 insertions, 0 deletions

diff --git a/demos/spectrum/TODO.txt b/demos/spectrum/TODO.txt
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+TODO list for spectrum analyser
+===============================
+
+Bug fixes
+---------
+
+
+New features
+------------
+
+* Wrap user-visible strings in tr()
+
+* Allow user to set frequency range
+There should be some constraints on this, e.g.
+	- Maximum frequency must not be greater than Nyquist frequency
+	- Range is divisible by number of bars?
+
+* Add more visualizers other than bar spectrogram
+e.g. Funky OpenGL visualizers, particle effects etc
+
+
+Non-functional stuff
+--------------------
+
+* Improve robustness of QComboBox -> enum mapping
+At the moment, SettingsDialog relies on casting the combobox item index directly to the enumerated type.  This is clearly a bit fragile...
+
+* For functions which take or return qint64 values, make a clear distinction between duration (microseconds) and length (bytes).
+A sensible convention would be that the default is bytes - i.e. microseconds must be indicated by adding a Us suffix, where not already obvious from the function name.
+
+
+
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