Added music21 and csound examples

ziffers/converters.py

@@ -7,12 +7,67 @@ try:
 except ImportError:
     music21_imported: bool = False
 
+try:
+    import ctcsound
+    csound_imported: bool = True
+except (ImportError, TypeError) as Error:
+    csound_imported: bool = False
+
+def freq_to_pch(freq: float) -> str:
+    "Format frequency to Csound PCH format"
+    return f"{freq:.2f}"
+
+# Csound score example: i1 0 1 0.5 8.00
+# 1. The first number is the instrument number. In this case it is instrument 1.
+# 2. The second number is the start time in seconds. In this case it is 0 seconds.
+# 3. The third number is the duration in seconds. In this case it is 1 second.
+# 4. The fourth number is the amplitude. In this case it is 0.5.
+# 5. The fifth number is the frequency. In this case it is 8 Hz.
+
+def freqs_and_durations_to_csound_score(pairs: list[list[float|list[float], float|list[float]]], bpm: int=80, amp: float=0.5, instr: (int|str)=1) -> str:
+    """Tranforms list of lists containing frequencies and note lengths to csound score format.
+       Note lengths are transformed in seconds with the bpm.
+       Start time in seconds is calculated and summed from the note lengths.
+       If frequency is None, then it is a rest.
+       If frequency is a list, then it is a chord.
+       
+       Example input: [[261.6255653005986, 0.5], [None, 0.25], [440.0, 0.125], [[261.6255653005986, 329.62755691286986, 391.9954359817492], [0.25, 0.125, 0.25]]]"""
+    score = ""
+    instr = f'"{instr}"' if isinstance(instr, str) else instr
+    start_time = 0
+    for pair in pairs:
+        if isinstance(pair[0], list):
+            for freq, dur in zip(pair[0], pair[1]):
+                score += f"i {instr} {start_time} {dur * 4 * 60 / bpm} {amp} {freq_to_pch(freq)}\n"
+            start_time += max(pair[1]) * 4 * 60 / bpm
+        else:
+            if pair[0] is None:
+                score += f"i {instr} {start_time} {pair[1] * 4 * 60 / bpm} {amp} 0\n"
+            else:
+                score += f"i {instr} {start_time} {pair[1] * 4 * 60 / bpm} {amp} {freq_to_pch(pair[0])}\n"
+            start_time += pair[1] * 4 * 60 / bpm
+    return score
+    
+def to_csound_score(expression: str | Ziffers, bpm: int=80, amp: float=0.5, instr: (int|str)=1) -> str:
+    """ Transform Ziffers object to Csound score """
+    if not csound_imported:
+        raise ImportError("Install Csound library")
+
+    if isinstance(expression, Ziffers):
+        score = freqs_and_durations_to_csound_score(expression.freq_pairs(),bpm,amp,instr)
+    else:
+        parsed = zparse(expression)
+        score = freqs_and_durations_to_csound_score(parsed.freq_pairs(),bpm,amp,instr)
+
+    return score
+
 def to_music21(expression: str | Ziffers, **options):
     """Helper for passing options to the parser"""
 
     if not music21_imported:
         raise ImportError("Install Music21 library")
 
+    # Register the ZiffersMusic21 converter
     converter.registerSubconverter(ZiffersMusic21)
 
     if isinstance(expression, Ziffers):