generalise python wave writer

common/wavesampler.py

@@ -0,0 +1,107 @@
+import struct
+from enum import Enum
+from riffwriter import AbstractRiffChunk
+from typing import BinaryIO, List
+
+
+class WaveSamplerSMPTEOffset:
+	def __init__(self, hours: int=0, minutes: int=0, seconds: int=0, frames: int=0):
+		if -23 > hours > 23:  raise ValueError("Hours out of range")
+		if 0 > minutes > 59:  raise ValueError("Minutes out of range")
+		if 0 > seconds > 59:  raise ValueError("Seconds out of range")
+		if 0 > frames > 0xFF: raise ValueError("Frames out of range")
+		self._hours   = hours
+		self._minutes = minutes
+		self._seconds = seconds
+		self._frames  = frames
+
+	def hours(self) -> int:   return self._hours
+	def minutes(self) -> int: return self._minutes
+	def seconds(self) -> int: return self._seconds
+	def frames(self) -> int:  return self._frames
+
+	def pack(self) -> bytes:
+		#FIXME: endianess??
+		return struct.pack("<bBBB", self._hours, self._minutes, self._seconds, self._frames)
+
+
+class WaveSamplerLoopType(Enum):
+	FORWARD = 0
+	BIDIRECTIONAL = 1
+	REVERSE = 2
+
+
+class WaveSamplerLoop:
+	def __init__(self,
+ 			cueId: int=0,
+			type: int|WaveSamplerLoopType=0,
+			start: int=0,
+			end: int=0,
+			fraction: int=0,
+			loopCount: int=0):
+		self._cueId = cueId
+		self._type = type.value if type is WaveSamplerLoopType else type
+		self._start = start
+		self._end = end
+		self._fraction = fraction
+		self._loopCount = loopCount
+
+	def pack(self) -> bytes:
+		return struct.pack("<IIIIII",
+			self._cueId,      # Cue point ID
+			self._type,       # Loop type
+			self._start,      # Loop start
+			self._end,        # Loop end
+			self._fraction,   # Fraction (none)
+			self._loopCount)  # Loop count (infinite)
+
+
+class WaveSamplerChunk(AbstractRiffChunk):
+	def fourcc(self) -> bytes: return b"smpl"
+
+	def loopsSize(self) -> int: return len(self._loops) * 24
+
+	def size(self) -> int: return 36 + self.loopsSize()
+
+	def write(self, f: BinaryIO):
+		#TODO: unused data dummied out for now
+		f.write(struct.pack("<4sIiiii4sII",
+			self._manufacturer,         # MMA Manufacturer code
+			self._product,              # Product
+			self._period,               # Playback period (ns)
+			self._unityNote,            # MIDI unity note
+			self._fineTune,             # MIDI pitch fraction
+			self._smpteFormat,          # SMPTE format
+			self._smpteOffset.pack(),   # SMPTE offset
+
+			len(self._loops),           # Number of loops
+			self.loopsSize()))          # Loop data length
+		f.writelines(loop.pack() for loop in self._loops)
+
+	def __init__(self,
+			manufacturer: bytes|None=None,
+			product: int=0,
+			period: int=0,
+			midiUnityNote: int=0,
+			midiPitchFraction: int=0,
+			smpteFormat: int=0,
+			smpteOffset: WaveSamplerSMPTEOffset|None=None,
+			loops: List[WaveSamplerLoop]=None):
+		if manufacturer is not None:
+			if len(manufacturer) not in [1, 3]: raise ValueError("Malformed MIDI manufacturer code")
+			self._manufacturer = len(manufacturer).to_bytes(1, byteorder="little", signed=False)
+			self._manufacturer += manufacturer.rjust(3, b"\x00")
+		else:
+			self._manufacturer = b"\x00" * 4
+
+		if 0 > product > 0xFFFF: raise ValueError("Product code out of range")
+		self._product = product # Arbitrary vendor specific product code, dunno if this should be signed or unsigned
+		self._period = period # Sample period in ns, (1 / samplerate) * 10^9, who cares
+		if 0 > midiUnityNote > 127: raise ValueError("MIDI Unity note out of range")
+		self._unityNote = midiUnityNote # MIDI note that plays the sample unpitched, middle C=60
+		self._fineTune = midiPitchFraction # Finetune fraction, 256 == 100 cents
+		if smpteFormat not in [0, 24, 25, 29, 30]: raise ValueError("Invalid SMPTE format")
+		self._smpteFormat = smpteFormat
+		self._smpteOffset = smpteOffset if (smpteOffset and smpteFormat > 0) else WaveSamplerSMPTEOffset()
+		if self._smpteOffset.frames() > self._smpteFormat: raise ValueError("SMPTE frame offset can't exceed SMPTE format")
+		self._loops = loops if loops is not None else list()