Abstract: A sigma delta digital-to-analog (D/A) converter system (10) includes a summing device (35) at an input of a D/A converter (30), and a low frequency low amplitude wave signal (31) injected at an input of the summing device that remains unfiltered and is used to suppress spurious tone artifacts. The D/A converter system can further include an amplitude control and a frequency control for selectively adjusting the frequency and the amplitude of the low frequency low amplitude wave signal being injected. Note, the low frequency low amplitude repeating wave signal generator can take the form of a digital signal processor (DSP) (37) having the appropriate software to generate such signals.

Abstract: Systems (100 or 300) and methods (400 or 500) are provided for selecting a post-compression waveform from a post-compression waveform table (106) and supplying it to a synthesis engine (108). The post-compression waveform is based upon a set of post-compression coefficients determined by generating a frequency-domain representation of a periodic signal, the representation including at least one pre-compression frequency-domain sample (204), and performing a threshold-based compression of the pre-compression frequency-domain samples. Systems and methods also include indexing and storing (502) post-compression coefficients in a post-compression coefficient table (102), generating (506) a post-compression waveform based upon the set of post-compression coefficients, and placing (508) the post-compression waveform in the table prior to the selecting (510).

Abstract: A method of scaling polyphony can include identifying music data to be played (415), wherein the music data indicates instruments to be used and each instrument has an assigned priority. A measure of polyphony needed to play the music data can be compared with polyphony of a sound generating device (425). If the measure of polyphony exceeds the polyphony of the sound generating device, the music data can be played without using one or more instruments indicated by the music data according to the assigned priorities (440, 460).

Abstract: A system, method and computer readable medium for adjusting volume levels of a Musical Instrument Digital Interface (MIDI) sound file for optimizing play on a sound device. The method on an information processing system includes calculating a first set of loudness levels for each instrument in a MIDI sound file and calculating a second set of loudness levels corresponding to an audio output range of a sound device. The method further includes generating a mapping between the first set of loudness levels and the second set of loudness levels corresponding to the audio output range of the sound device. The method further includes generating a gain term for each note in the MIDI sound file and modifying the MIDI sound file using the second set of loudness levels and the gain term for each note in the MIDI sound file.