pandora_cdosea/render_audio.py

#!/usr/bin/python
import os
import time
import sys
import json

import mlt
from PyQt5 import QtWidgets

# Avoid segfault in webvfx
app = QtWidgets.QApplication(sys.argv)

#mlt.mlt_log_set_level(40)  # verbose
mlt.Factory.init()


tractor = mlt.Tractor()
tractor.mark_in = -1
tractor.mark_out = -1

multitrack = tractor.multitrack()

source = sys.argv[1]
target = source.replace('.json', '.audio.xml')

with open(source) as fd:
    data = json.load(fd)

music = mlt.Playlist()
vocals = mlt.Playlist()

fps = 60
profile = mlt.Profile("atsc_1080p_%d" % fps)

def add_clip(playlist, file_, duration):
    in_ = 0
    if not isinstance(file_, str):
        file_ = file_.encode('utf-8')
    clip = mlt.Producer(profile, file_)
    clip.set_in_and_out(in_, in_+duration-1)
    playlist.append(clip)

def add_blank(playlist, length):
    playlist.blank(length)

for clip in data['music']:
    frames = int(clip['duration'] * fps)
    if clip.get('blank'):
        add_blank(music, frames)
    else:
        add_clip(music, clip['path'], frames)

for clip in data['vocals']:
    frames = int(clip['duration'] * fps)
    if clip.get('blank'):
        add_blank(vocals, frames)
    else:
        add_clip(vocals, clip['path'], frames)

multitrack.connect(vocals, 0)
multitrack.connect(music, 1)
composite = mlt.Transition(profile, "mix")
composite.set("start", 0.01)
composite.set("end", 0.01)
composite.set("combine", 1)

tractor.plant_transition(composite)

consumer = 'xml'
consumer = mlt.Consumer(profile, consumer, target)
consumer.connect(tractor)
#consumer.set("real_time", -2)
consumer.start()