Java中如何取得midi音乐的最大和弦数
midi音乐的最大和弦数就是最大复音数，所谓复音就是同一时间点（tick）有多种声音，而这时的声音的种数就是复音数，最大复音数就是一首乐曲中复音数最大的那个时间点的复音数。在midi中声音是使用事件（Event）来记录的，事件有发生时间（tick）和该事件的内容（MidiMessage，即声音）两个属性。所以，复音数在midi里面就是同一个tick的事件的个数，最大复音数就是其最大值。java程序如下：public long getMaxChordNum(String midi); throws Exception { File mf = new File(midi);; Map m = new HashMap();; Track[] tracks = MidiSystem.getSequence(mf);.getTracks();; for (int i = 0; i < tracks.length; i++); { for (int j = 0; j < tracks.size();; j++); { Long ltick = new Long(tracks.get(j);.getTick(););; if (ltick.longValue(); == 0L); { continue; } if (m.containsKey(ltick);); { Long value = (Long); m.get(ltick);; m.put(ltick, new Long(value.longValue(); + 1););; } else { m.put(ltick, new Long(1););; } } } Set keys = m.keySet();; Iterator keyit = keys.iterator();; long max = 0; while (keyit.hasNext();); { Long key = (Long); keyit.next();; Long value = (Long); m.get(key);; long tmp = value.longValue();; if (tmp > max); { max = tmp; } } return max; }
效率提高版
public long getMaxChordNum(Track[] tracks); throws Exception { long max = 0; if (tracks != null && tracks.length > 0); { int size = 0; for (int i = 0; i < tracks.length; i++); { size += tracks.size();; } long[] ticks = new long; int idx = 0; for (int i = 0; i < tracks.length; i++); { for (int j = 0; j < tracks.size();; j++); { ticks = tracks.get(j);.getTick();; } } Arrays.sort(ticks);; long pretick = 0; long precnt = 1; for (int i = 0; i < size; i++); { if (ticks == 0); continue; if (ticks == pretick); { precnt++; } else { max = max < precnt ? precnt : max; pretick = ticks; precnt = 1; } } max = max < precnt ? precnt : max; } return max; }
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