VS1053B Datasheet, PDF (32/79 Pages) List of Unclassifed Manufacturers – Ogg Vorbis/MP3/AAC/WMA/MIDI AUDIO CODEC

VLSI
Solution ^y
VS1053b preliminary
VS1053B
8. FUNCTIONAL DESCRIPTION
8.2.8 Supported MIDI Formats
General MIDI and SP-MIDI format 0 files are played. Format 1 and 2 files must be converted to format 0
by the user. The maximum polyphony is 64, the maximum sustained polyphony is 40. Actual polyphony
depends on the internal clock rate (which is user-selectable), the instruments used, whether the reverb
effect is enabled, and the possible global postprocessing effects enabled, such as bass enhancer, treble
control or EarSpeaker spatial processing. The polyphony restriction algorithm makes use of the SP-MIDI
MIP table, if present, and uses smooth note removal.
43 MHz (3.5× input clock) achieves 19-31 simultaneous sustained notes. The instantaneous amount of
notes can be larger. This is a fair compromise between power consumption and quality, but higher clocks
can be used to increase polyphony.
Reverb effect can be controlled by the user. In addition to reverb automatic and reverb off modes, 14
different decay times can be selected. These roughly correspond to different room sizes. Also, each
midi song decides how much effect each instrument gets. Because the reverb effect uses about 4 MHz of
processing power the automatic control enables reverb only when the internal clock is at least 3.0×.
In VS1053b both EarSpeaker and MIDI reverb can be on simultaneously. This is ideal for listening MIDI
songs with headphones.
New instruments have been implemented in addition to the 36 that are available in VS1003. VS1053b
now has unique instruments in the whole GM1 instrument set and one bank of GM2 percussions.
Version 0.5, 2007-12-03
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