import os
from subprocess import call, check_output
import uuid
from xml.etree.ElementTree import Element, tostring, fromstring
from . import config
from .clip import Clip
from .utils import timestamp, check_melt
[docs]class Composition(object):
'''A composition made of a list of clips.
Args:
clips (list): A list of Clip objects
bgcolor (str): The background color of the composition, in hex
singletrack (bool): Boolean that determines if clips play all at once (default) or sequentially
duration (float): Duration of the composition in seconds.
fps (int): Frames per second of output
width (int): Width of output in pixels
height (int): Height of output in pixels
'''
def __init__(self, clips, bgcolor='#000000', singletrack=False, duration=None, fps=None, width=None, height=None):
self.clips = clips
self.bg = bgcolor
self.singletrack = singletrack
self.duration = timestamp(duration)
self.fps = fps
self.width = width
self.height = height
def autoset_duration(self, xml):
duration = self.duration
if not duration:
duration = self.duration = xml.find('tractor').get('out')
xml.find('tractor').set('out', str(duration))
xml.find('producer').set('out', str(duration))
xml.find('producer').remove(xml.find('./producer/property[@name="length"]'))
xml.find('./playlist/entry').set('out', str(duration))
return xml
def set_meta(self, xml):
profile = xml.find('profile')
if self.fps:
profile.set('frame_rate_num', str(self.fps))
if self.width and self.height:
profile.set('width', str(self.width))
profile.set('display_aspect_num', str(self.width))
profile.set('height', str(self.height))
profile.set('display_aspect_den', str(self.height))
return xml
[docs] def xml(self):
'''Renders the composition as XML and sets the current duration, width, height and fps.
Returns:
str: an mlt xml representation of the composition
'''
xml = check_output(self.args() + ['-consumer', 'xml'])
xml = fromstring(xml)
xml = self.autoset_duration(xml)
xml = self.set_meta(xml)
return tostring(xml)
[docs] def save_xml(self, filename=None):
'''Saves the composition as a mlt xml file.
Args:
filename (str): path to save to
Returns:
str: path to the saved file
'''
if filename is None:
filename = str(uuid.uuid4()) + '.xml'
with open(filename, 'wb') as outfile:
outfile.write(self.xml())
return filename
[docs] def preview(self):
''' Previews the composition using melt's default viewer.'''
check_melt()
xmlfile = self.save_xml()
call([config.MELT_BINARY, xmlfile, 'out="{}"'.format(self.duration)])
os.remove(xmlfile)
[docs] def save(self, filename, **kwargs):
'''Save the composition as a video file.
Args:
filename (str): the file to save to (any video type is accepted)
**kwargs: additional parameters to pass to ffmpeg
Returns:
filename (str): the path to the saved file
'''
check_melt()
xmlfile = self.save_xml()
args = [
config.MELT_BINARY,
xmlfile,
'out="{}"'.format(self.duration),
'-consumer',
'avformat:{}'.format(filename)
]
extra_params = ['{}="{}"'.format(key, val) for key, val in kwargs.items()]
args += extra_params
call(args)
os.remove(xmlfile)
return filename
[docs] def args(self):
'''Generate mlt command line arguments
Returns:
str: mlt command line arguments
'''
args = [config.MELT_BINARY]
# add the the background track
args += ['-track', 'color:{}'.format(self.bg), 'out=0']
# add a track for all clips in singletrack
if self.singletrack:
args += ['-track']
# add args and transitions for all clips
for i, c in enumerate(self.clips):
c.track_number = i + 1
args += c.args(self.singletrack)
args += c.transition_args(i+1)
# add mask clips
for i, c in enumerate(self.clips):
if c.mask:
args += c.mask.args()
# add matte transitions for mask clips
mask_track_number = len(self.clips)
for i, c in enumerate(self.clips):
if c.mask:
args += ['-transition', 'matte', 'a_track={}'.format(c.track_number), 'b_track={}'.format(mask_track_number)]
mask_track_number += 1
# add composite transitions for all tracks
if self.singletrack:
args += ['-transition', 'composite', 'distort=0', 'a_track=0', 'b_track=1']
else:
for i, c in enumerate(self.clips):
args += ['-transition', 'composite', 'distort=0', 'a_track=0', 'b_track={}'.format(i+1)]
args += ['-transition', 'mix', 'a_track=0', 'b_track={}'.format(i+1)]
return args
def __str__(self):
return ' '.join(self.args())
