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imaging.py
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imaging.py

import os
import json
import subprocess
from PIL import Image
from flask import current_app
def generate_local_thumbnails(name_base, src):
"""Given a source image, use Pillow to generate thumbnails according to the
application settings.
:param name_base: the thumbnail will get a field 'name': '{basename}-{thumbsize}.jpg'
:type name_base: str
:param src: the path of the image to be thumbnailed
:type src: str
"""
thumbnail_settings = current_app.config['UPLOADS_LOCAL_STORAGE_THUMBNAILS']
thumbnails = []
save_to_base, _ = os.path.splitext(src)
name_base, _ = os.path.splitext(name_base)
for size, settings in thumbnail_settings.iteritems():
dst = '{0}-{1}{2}'.format(save_to_base, size, '.jpg')
name = '{0}-{1}{2}'.format(name_base, size, '.jpg')
if settings['crop']:
resize_and_crop(src, dst, settings['size'])
width, height = settings['size']
else:
im = Image.open(src).convert('RGB')
im.thumbnail(settings['size'])
im.save(dst, "JPEG")
width, height = im.size
thumb_info = {'size': size,
'file_path': name,
'local_path': dst,
'length': os.stat(dst).st_size,
'width': width,
'height': height,
'md5': '',
'content_type': 'image/jpeg'}
if size == 't':
thumb_info['is_public'] = True
thumbnails.append(thumb_info)
return thumbnails
def resize_and_crop(img_path, modified_path, size, crop_type='middle'):
"""
Resize and crop an image to fit the specified size. Thanks to:
https://gist.github.com/sigilioso/2957026
args:
img_path: path for the image to resize.
modified_path: path to store the modified image.
size: `(width, height)` tuple.
crop_type: can be 'top', 'middle' or 'bottom', depending on this
value, the image will cropped getting the 'top/left', 'middle' or
'bottom/right' of the image to fit the size.
raises:
Exception: if can not open the file in img_path of there is problems
to save the image.
ValueError: if an invalid `crop_type` is provided.
"""
# If height is higher we resize vertically, if not we resize horizontally
img = Image.open(img_path).convert('RGB')
# Get current and desired ratio for the images
img_ratio = img.size[0] / float(img.size[1])
ratio = size[0] / float(size[1])
# The image is scaled/cropped vertically or horizontally depending on the ratio
if ratio > img_ratio:
img = img.resize((size[0], int(round(size[0] * img.size[1] / img.size[0]))),
Image.ANTIALIAS)
# Crop in the top, middle or bottom
if crop_type == 'top':
box = (0, 0, img.size[0], size[1])
elif crop_type == 'middle':
box = (0, int(round((img.size[1] - size[1]) / 2)), img.size[0],
int(round((img.size[1] + size[1]) / 2)))
elif crop_type == 'bottom':
box = (0, img.size[1] - size[1], img.size[0], img.size[1])
else:
raise ValueError('ERROR: invalid value for crop_type')
img = img.crop(box)
elif ratio < img_ratio:
img = img.resize((int(round(size[1] * img.size[0] / img.size[1])), size[1]),
Image.ANTIALIAS)
# Crop in the top, middle or bottom
if crop_type == 'top':
box = (0, 0, size[0], img.size[1])
elif crop_type == 'middle':
box = (int(round((img.size[0] - size[0]) / 2)), 0,
int(round((img.size[0] + size[0]) / 2)), img.size[1])
elif crop_type == 'bottom':
box = (img.size[0] - size[0], 0, img.size[0], img.size[1])
else:
raise ValueError('ERROR: invalid value for crop_type')
img = img.crop(box)
else:
img = img.resize((size[0], size[1]),
Image.ANTIALIAS)
# If the scale is the same, we do not need to crop
img.save(modified_path, "JPEG")
def get_video_data(filepath):
"""Return video duration and resolution given an input file path"""
outdata = None
ffprobe_inspect = [
current_app.config['BIN_FFPROBE'],
'-loglevel',
'error',
'-show_streams',
filepath,
'-print_format',
'json']
ffprobe_ouput = json.loads(subprocess.check_output(ffprobe_inspect))
video_stream = None
# Loop throught audio and video streams searching for the video
for stream in ffprobe_ouput['streams']:
if stream['codec_type'] == 'video':
video_stream = stream
if video_stream:
# If video is webm we can't get the duration (seems to be an ffprobe
# issue)
if video_stream['codec_name'] == 'vp8':
duration = None
else:
duration = int(float(video_stream['duration']))
outdata = dict(
duration=duration,
res_x=video_stream['width'],
res_y=video_stream['height'],
)
if video_stream['sample_aspect_ratio'] != '1:1':
print '[warning] Pixel aspect ratio is not square!'
return outdata
def ffmpeg_encode(src, format, res_y=720):
# The specific FFMpeg command, called multiple times
args = []
args.append("-i")
args.append(src)
if format == 'mp4':
# Example mp4 encoding
# ffmpeg -i INPUT -vcodec libx264 -pix_fmt yuv420p -preset fast -crf 20
# -acodec libfdk_aac -ab 112k -ar 44100 -movflags +faststart OUTPUT
args.extend([
'-threads', '1',
'-vf', 'scale=-2:{0}'.format(res_y),
'-vcodec', 'libx264',
'-pix_fmt', 'yuv420p',
'-preset', 'fast',
'-crf', '20',
'-acodec', 'libfdk_aac', '-ab', '112k', '-ar', '44100',
'-movflags', '+faststart'])
elif format == 'webm':
# Example webm encoding
# ffmpeg -i INPUT -vcodec libvpx -g 120 -lag-in-frames 16 -deadline good
# -cpu-used 0 -vprofile 0 -qmax 51 -qmin 11 -slices 4 -b:v 2M -f webm
args.extend([
'-vf', 'scale=-2:{0}'.format(res_y),
'-vcodec', 'libvpx',
'-g', '120',
'-lag-in-frames', '16',
'-deadline', 'good',
'-cpu-used', '0',
'-vprofile', '0',
'-qmax', '51', '-qmin', '11', '-slices', '4', '-b:v', '2M',
# '-acodec', 'libmp3lame', '-ab', '112k', '-ar', '44100',
'-f', 'webm'])
if not os.environ.get('VERBOSE'):
args.extend(['-loglevel', 'quiet'])
dst = os.path.splitext(src)
dst = "{0}-{1}p.{2}".format(dst[0], res_y, format)
args.append(dst)
print "Encoding {0} to {1}".format(src, format)
returncode = subprocess.call([current_app.config['BIN_FFMPEG']] + args)
if returncode == 0:
print "Successfully encoded {0}".format(dst)
else:
print "Error during encode"
print "Code: {0}".format(returncode)
print "Command: {0}".format(current_app.config['BIN_FFMPEG'] + " " + " ".join(args))
dst = None
# return path of the encoded video
return dst

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