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demo.py
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demo.py
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"""
demo.py - PyOPL usage example.
Copyright (C) 2011-2012 Adam Nielsen <[email protected]>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
from struct import *
import pyopl
import pyaudio
import sys
import os.path
# Playback frequency. Try a different value if the output sounds stuttery.
freq = 44100
# How many bytes per sample (2 == 16-bit samples). This is the only value
# currently implemented.
sample_size = 2
# How many channels to output (2 == stereo). The OPL2 is mono, so in stereo
# mode the mono samples are copied to both channels. Enabling OPL3 mode will
# switch the synth to true stereo (and in this case setting num_channels=1
# will just drop the right channel.) It is done this way so that you can set
# num_channels=2 and output stereo data, and it doesn't matter whether the
# synth is in OPL2 or OPL3 mode - it will always work.
num_channels = 2
# How many samples to synthesise at a time. Higher values will reduce CPU
# usage but increase lag.
synth_size = 512
# An OPL helper class which handles the delay between notes and buffering
class OPLStream:
def __init__(self, freq, ticksPerSecond):
self.opl = pyopl.opl(freq, sampleSize=sample_size, channels=num_channels)
self.ticksPerSecond = ticksPerSecond
self.buf = bytearray(synth_size * sample_size * num_channels)
# Python 3 doesn't have Python 2's buffer() builtin and _portaudio doesn't work with memoryview,
# convert to bytes() as needed, which isn't as efficient.
OPLStream.pyaudio_buf = property(lambda self: bytes(self.buf))
self.delay = 0
def writeReg(self, reg, value):
self.opl.writeReg(reg, value)
def wait(self, ticks):
# Rather than calculating the exact number of samples we need to generate,
# we just keep generating 512 samples at a time until we've waited as close
# as possible to the requested delay.
# This does mean we might wait for up to 511/freq samples too little (at
# 48kHz that's a worst-case of 10.6ms too short) but nobody should notice
# and it saves enough CPU time and complexity to be worthwhile.
self.delay += ticks * freq / self.ticksPerSecond
while self.delay > synth_size:
self.opl.getSamples(self.buf)
# We put the samples into self.buf which also updates self.pyaudio_buf
stream.write(self.pyaudio_buf)
self.delay -= synth_size
# This is an alternate way of calculating the delay. It has slightly higher
# CPU usage but provides more accurate delays (+/- 0.04ms).
# To use it, rename the function to "wait" and rename the other "wait"
# function to something else.
def wait2(self, ticks):
# Figure out how many samples we need to get to obtain the delay
fill = ticks * freq // self.ticksPerSecond
tail = fill % synth_size
if tail:
buf_tail = bytearray(tail * sample_size * num_channels)
# Fill the buffer in 512-sample lots until full
cur = self.buf
while fill > 1: # DOSBox synth can't generate < 2 samples
if fill < synth_size:
# Resize the buffer for the last bit
cur = buf_tail
self.opl.getSamples(cur)
# Python 3 doesn't have Python 2's buffer() builtin and _portaudio doesn't work with memoryview,
# convert to bytes() as needed, which isn't as efficient.
pyaudio_buf = bytes(cur)
stream.write(pyaudio_buf)
fill -= synth_size
## Main code begins ##
# Require a filename to be given on the command line
if len(sys.argv) != 2:
print("Please specify one IMF filename.")
sys.exit()
# Open the file given on the command line
i = open(sys.argv[1], 'rb')
# Check the first two bytes to see what the file version is
chunk = i.read(2)
lenData, = unpack('H', chunk)
if lenData == 0:
print("Type-0 format detected")
i.seek(0)
else:
print("Type-1 format detected")
# Check the file extension to see how fast we should play it
dummy, ext = os.path.splitext(sys.argv[1])
if ext.lower() == '.wlf': ticksPerSecond = 700
else: ticksPerSecond = 560
print("{} Hz file detected".format(ticksPerSecond))
# Set up the audio stream
audio = pyaudio.PyAudio()
stream = audio.open(
format = audio.get_format_from_width(sample_size),
channels = num_channels,
rate = freq,
output = True)
# At this point we have to hope PyAudio has got us the audio format we
# requested. It doesn't always, but it lacks functions for us to check.
# This means we could end up outputting data in the wrong format...
# Set up the OPL synth
oplStream = OPLStream(freq, ticksPerSecond)
# Enable Wavesel on OPL2
oplStream.writeReg(1, 32)
# Enable OPL3 mode (this will likely mute the output, see below)
#oplStream.writeReg(0x105, 1)
lenRead = 0
channelActive = [0] * 9
core = []
perc = []
try:
while lenRead < lenData or lenData == 0:
# Read the next OPL bytes from the file
chunk = i.read(4)
lenRead += 4
if not chunk: break
reg, val, delay = unpack('BBH', chunk)
# Send them to the synth
oplStream.writeReg(reg, val)
## EXAMPLE: Write to upper half of OPL3
## First, override the panning register to make the sound come out of both
## channels. This is required if playing OPL2 data, as these registers are
## unused on the OPL2 so are usually set to zero, silencing the channel.
## You won't need this if you're playing native OPL3 data.
#if reg & 0xC0 == 0xC0:
# val = val | 0x30
## Write the same value to the same register on the upper register set
#oplStream.writeReg(0x100 + reg, val)
# Show something that moves to be a bit more interesting
if reg & 0xB0 == 0xB0:
c = reg & 0x0F
if c < 9:
channelActive[c] = val & 0x20
core = ["\r"]
for x in channelActive:
if x: core.append('-')
else: core.append('_')
if reg == 0xBD and val & 0x20:
perc = [' ']
for x in range(0, 5):
if (val >> x) & 1: perc.append('=')
else: perc.append('.')
sys.stdout.write(''.join(core))
sys.stdout.write(''.join(perc))
sys.stdout.flush()
# Wait for the given number of ticks
if delay: oplStream.wait(delay)
except EOFError:
pass
except KeyboardInterrupt:
pass
print
stream.close()
audio.terminate()