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mixtape.py
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mixtape.py
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import argparse
from collections import namedtuple
import numpy
import os
import subprocess
import sys
import tempfile
import scipy.io.wavfile
import sounddevice
Wav = namedtuple('Wav', ['sample_rate', 'data'])
Segment = namedtuple('Segment', ['time', 'wav'])
def convert_mp3_to_wav(mp3filename, wavfilename):
"""
Convert an MP3 file to a WAV filename
:param mp3filename: path of mp3. Assumed to exist.
:param wavfilename: path to wav to write. Existing file will not be overwritten.
"""
if not os.path.exists(wavfilename):
cmd = ['ffmpeg',
'-n',
'-i',
mp3filename,
wavfilename]
subprocess.run(cmd, check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
def convert_wav_to_mp3(wavfilename, mp3filename, force):
"""
Convert a WAV file to an MP3 file
:param wavfilename: path of wav. Assumed to exist.
:param mp3filename: path to mp3 to write. Existing file will be overwritten only if force is True
:param force: Whether to overwrite existing output file
"""
cmd = ['ffmpeg',
'-y' if force else '-n',
'-i',
wavfilename,
mp3filename]
subprocess.run(cmd, check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
def read_wav(wavfilename):
"""
:param wavfilename: Filename to read
:return: Wav
"""
return Wav._make(scipy.io.wavfile.read(wavfilename))
def write_segments_to_wav(segments, outwavfilename):
"""
:param wavdata: Wav to write
:param outwavfilename: Filename to write to
"""
sample_rate = segments[0].wav.sample_rate
assert(all((segment.wav.sample_rate == sample_rate) for segment in segments))
outwav_data = numpy.concatenate([segment.wav.data for segment in segments])
scipy.io.wavfile.write(outwavfilename, sample_rate, outwav_data)
def play_segments(segments):
"""
Play the given list of segments, reporting progress to stdout
:param segments: list of Segment
"""
display_size = os.get_terminal_size().columns
try:
for segment in segments:
print(segment.time.ljust(display_size-1), end='\r')
sounddevice.play(segment.wav.data, segment.wav.sample_rate)
sounddevice.wait()
except KeyboardInterrupt:
pass
except:
raise
print('')
def format_time(seconds):
"""
Format a time for printing
:param seconds: integer number of seconds
:return: string representation of minutes and seconds
"""
mins, secs = divmod(seconds, 60)
return '%u:%02u' % (mins, secs)
def input_wav(args, input_filename):
"""
Read an input file into memory, coping with multiple file formats
:param args: Program arguments - return value from parse_args()
:param input_filename: File to read
:return: Wav
"""
if input_filename.endswith('.mp3'):
leafname = os.path.splitext(os.path.basename(input_filename))[0] + '.wav'
inwav_filename = os.path.join(args.tmpdir.name, leafname)
convert_mp3_to_wav(input_filename, inwav_filename)
elif input_filename.endswith('.wav'):
inwav_filename = input_filename
else:
raise Exception("Unrecognised input file format: "+input_filename)
return read_wav(inwav_filename)
def extract_beginning(args, inputs):
"""
Extract the segment at the beginning of the first input file
:param args: Program arguments - return value from parse_args()
:param inputs: Files to read
:return: list of Segment
"""
inwav = input_wav(args, inputs[0])
begin_pos = 0
end_pos = int(args.length * inwav.sample_rate)
return [Segment('%s: First %s seconds' % (os.path.basename(inputs[0]), args.length), Wav(inwav.sample_rate, inwav.data[begin_pos:end_pos]))]
def extract_end(args, inputs):
"""
Extract the segment at the end of the first input file
:param args: Program arguments - return value from parse_args()
:param inputs: Files to read
:return: list of Segment
"""
inwav = input_wav(args, inputs[0])
begin_pos = -int(args.length * inwav.sample_rate)
return [Segment('%s: Last %s seconds' % (os.path.basename(inputs[0]), args.length), Wav(inwav.sample_rate, inwav.data[begin_pos:]))]
def extract_slice(args, inputs):
"""
Extract the slice of segments across all input files.
:param args: Program arguments - return value from parse_args()
:param inputs: Files to read
:return: list of Segment
"""
segments = []
for filename in inputs:
begin_pos = 0
pos_name = 0
inwav = input_wav(args, filename)
while begin_pos < len(inwav.data):
end_pos = int(begin_pos + args.length * inwav.sample_rate)
segments.append(Segment('%s: %s' % (os.path.basename(filename), format_time(pos_name)),
Wav(inwav.sample_rate, inwav.data[begin_pos:end_pos])))
begin_pos += int((args.length + args.skip) * inwav.sample_rate)
pos_name += args.length + args.skip
return segments
def extract_transition(args, inputs):
"""
Extract the segment at the end of one file and the beginning of the next.
:param args: Program arguments - return value from parse_args()
:param inputs: Files to read
:return: list of Segment
"""
segments = []
index = 0
while index < len(inputs)-1:
segments.extend(extract_end(args, inputs[index:index+1]))
index += 1
segments.extend(extract_beginning(args, inputs[index:index+1]))
return segments
def parse_args():
"""
Parse program command-line arguments
:return: ArgumentParser namespace.
"""
parser = argparse.ArgumentParser()
output_group = parser.add_mutually_exclusive_group(required=True)
output_group.add_argument('-o', '--output',
help="Specify the output filename")
output_group.add_argument('--play', action='store_true',
help="Play, rather than writing an output file")
parser.add_argument('-f', '--force', action='store_true',
help="Force overwrite existing output file.")
extraction_group = parser.add_mutually_exclusive_group(required=True)
extraction_group.add_argument('--beginning', action='store_const', const=extract_beginning, dest='extractor',
help="Play/extract the beginning few seconds of music")
extraction_group.add_argument('--end', action='store_const', const=extract_end, dest='extractor',
help="Play/extract the last few seconds of music")
extraction_group.add_argument('--slice', action='store_const', const=extract_slice, dest='extractor',
help="Play/extract slices of music throughout the track")
extraction_group.add_argument('--transition', action='store_const', const=extract_transition, dest='extractor',
help="Play/extract the end of one song and the beginning of the next. "
"Multiple transitions are supported.")
selector_group = parser.add_argument_group()
selector_group.add_argument('-l', '--length', action='store', type=float,
help="For --beginning/--end: Specify length of music to extract (in seconds)."
"For --slice: Specify length of sections of music to keep (in seconds).")
selector_group.add_argument('-k', '--skip', action='store', type=float,
help="For --slice: Specify length of sections of music to skip (in seconds).")
parser.add_argument('input', nargs='+',
help="Specify the input filename. May be specified multiple times for --transition and --slice.")
parser.set_defaults(input=[], output=None, play=False, length=1.0, skip=5.0)
args = parser.parse_args()
if (args.length <= 0) or (args.skip <= 0):
parser.error("Length and skip lengths must be greater than 0")
if args.length is None:
args.length = 30.0 if (args.extractor in (extract_beginning, extract_end, extract_transition)) else 1
if (args.extractor == extract_slice) and (args.skip is None):
args.skip = 5.0
if (args.extractor == extract_transition) and (len(args.input) < 2):
parser.error("2 or more input files are required for transition mode")
args.tmpdir = tempfile.TemporaryDirectory()
return args
def main():
"""
Main function
"""
args = parse_args()
for filename in args.input:
if not os.path.exists(filename):
sys.exit("%s not found" % filename)
if args.output and os.path.exists(args.output) and not args.force:
sys.exit("Output file exists. Refusing to overwrite.")
segments = args.extractor(args, args.input)
if args.play:
play_segments(segments)
else:
if args.output.endswith('.mp3'):
outwavfilename = os.path.join(args.tmpdir.name, 'output.wav')
write_segments_to_wav(segments, outwavfilename)
convert_wav_to_mp3(outwavfilename, args.output, args.force)
else:
write_segments_to_wav(segments, args.output)
if __name__ == '__main__':
main()