Added python-pyaudio example

1 files changed, 174 insertions, 0 deletions

diff --git a/examples/python-pyaudio/playmidi.py b/examples/python-pyaudio/playmidi.py
new file mode 100755
index 0000000..aae3a26
--- /dev/null
+++ b/examples/python-pyaudio/playmidi.py
@@ -0,0 +1,174 @@
+#!/usr/bin/python3
+
+import sys
+import time
+import signal
+import getopt
+import pyaudio
+import platform
+
+from ctypes import *
+
+if platform.system() == 'Windows':
+    adl = CDLL("libADLMIDI.dll")
+else:
+    adl = CDLL("libADLMIDI.so")
+
+_FREQUENCY = 44100
+
+playing = True
+
+# Allows to quit by Ctrl+C
+def catch_signal(signum, frame):
+    global playing
+    playing = False
+    print("Caught Ctrl+C!")
+
+
+class MidiPlayer:
+    """A streaming IMF music player."""
+    SAMPLE_SIZE = 2  # 16-bit
+    CHANNELS = 2  # stereo
+    BUFFER_SAMPLE_COUNT = 1024  # Max allowed: 512
+
+    def __init__(self, freq=_FREQUENCY):
+        """Initializes the PyAudio and OPL synth."""
+        self._freq = freq
+        # Prepare PyAudio
+        self._audio = pyaudio.PyAudio()
+        # Prepare buffers.
+        self._data = create_string_buffer(MidiPlayer.BUFFER_SAMPLE_COUNT * MidiPlayer.SAMPLE_SIZE * MidiPlayer.CHANNELS)
+        self._stream = None  # Created later.
+        self._opl = adl.adl_init(freq)
+        self._song = None
+
+    def set_bank_no(self, bank_no):
+        if adl.adl_setBank(self._opl, bank_no):
+            print("%s" % c_char_p(adl.adl_errorInfo(self._opl)).value)
+            return False
+        return True
+
+    def set_bank_file(self, bank_file):
+        if adl.adl_openBankFile(self._opl, bank_file) < 0:
+            print("%s" % c_char_p(adl.adl_errorInfo(self._opl)).value)
+            return False
+        return True
+
+    def set_loop_enabled(self, loop_en):
+        print(loop_en)
+        adl.adl_setLoopEnabled(self._opl, 1 if loop_en else 0)
+
+    def _create_stream(self, start=True):
+        """Create a new PyAudio stream."""
+        self._stream = self._audio.open(
+            format=self._audio.get_format_from_width(MidiPlayer.SAMPLE_SIZE),
+            channels=MidiPlayer.CHANNELS,
+            frames_per_buffer=MidiPlayer.BUFFER_SAMPLE_COUNT,
+            rate=self._freq,
+            output=True,
+            start=start,  # Don't start playing immediately!
+            stream_callback=self._callback)
+
+    def set_song(self, song):
+        self._song = song
+        if adl.adl_openFile(self._opl, self._song.encode()) < 0:
+            print("%s" % c_char_p(adl.adl_errorInfo(self._opl)).value.decode())
+            return False
+
+        return True
+
+    # noinspection PyUnusedLocal
+    def _callback(self, input_data, frame_count, time_info, status):
+        global playing
+        got = adl.adl_play(self._opl, int(MidiPlayer.BUFFER_SAMPLE_COUNT * 2), cast(self._data, POINTER(c_short)));
+        if got <= 0:
+            playing = False
+            return None, pyaudio.paComplete
+        return self._data, pyaudio.paContinue
+
+    def play(self, repeat=False):
+        global playing
+        """Starts playing the song at the current position."""
+        self.repeat = repeat
+        if self._song is None:
+            playing = False
+            return
+        # If a stream exists and it is not active and not stopped, it needs to be closed and a new one created.
+        if self._stream is not None and not self._stream.is_active() and not self._stream.is_stopped():
+            self._stream.close()  # close for good measure.
+            self._stream = None
+
+        # If there's no stream at this point, create one.
+        if self._stream is None:
+            self._create_stream(False)
+        self._stream.start_stream()
+
+    def pause(self):
+        """Stops the PyAudio stream, but does not rewind the playback position."""
+        self._stream.stop_stream()
+
+    def stop(self):
+        """Stops the PyAudio stream and resets the playback position."""
+        self._stream.stop_stream()
+
+    def close(self):
+        """Closes the PyAudio stream and terminates it."""
+        if self._stream is not None:
+            self._stream.stop_stream()
+            self._stream.close()
+            self._stream = None
+        self._audio.terminate()
+        adl.adl_close(self._opl)
+
+
+def usage(arg):
+    print('usage: %s [-b <embedded bank number>|-bf <external bank file>] [-l 0|1] <file>' % arg, file=sys.stderr)
+    sys.exit(2)
+
+if __name__ == '__main__':
+    bank_no = 72
+    bank_file = None
+    enable_loop = False
+    sample_rate = 44100
+
+    opts, args = getopt.getopt(sys.argv[1:], 'b:bg:l:')
+    for o, a in opts:
+        if o == '-b':
+            bank_no = int(a)
+        if o == '-l':
+            enable_loop = int(a) == 1
+        elif o == '-bg':
+            bank_file = a
+
+    if not args:
+        usage(sys.argv[0])
+
+    midi_file = args[0]
+
+    MIDIPlay = MidiPlayer(sample_rate)
+
+    if bank_file:
+        if not MIDIPlay.set_bank_file(bank_file):
+            exit(1)
+        print("Using bank file: %s" % bank_file)
+    else:
+        if not MIDIPlay.set_bank_no(bank_no):
+            exit(1)
+        print("Using embedded bank: %d" % bank_no)
+
+    MIDIPlay.set_loop_enabled(enable_loop)
+
+    if not MIDIPlay.set_song(midi_file):
+        exit(1)
+
+    MIDIPlay.play()
+
+    signal.signal(signal.SIGINT, catch_signal)
+
+    print("Playing MIDI file %s..." % (midi_file))
+    while playing:
+        time.sleep(0.1)
+    MIDIPlay.stop()
+
+    MIDIPlay.close()
+