prepare_images.py

   1 #!/usr/bin/python
   2
   3 import os, sys, re
   4 import subprocess
   5 import array
   6 import struct
   7 import Image
   8 from itertools import count
   9
  10 from sparrow import FRAME_STRUCTURE, INDEX_FILE, TEXT_INDEX_FILE, BLOB_NAME
  11 from sparrow import save_frames, save_frames_text, link_frames
  12 from sparrow import Frame
  13
  14 class Sequence:
  15     def __init__(self, seq_id):
  16         self.id = seq_id
  17         self.frames = []
  18         self.append = self.frames.append
  19
  20
  21 def stretch(im, size, filter=Image.NEAREST):
  22     im.load()
  23     im = im._new(im.im.stretch(size, filter))
  24     return im
  25
  26 def downscale_pil(jpeg_data):
  27     p = subprocess.Popen(['djpeg', '-scale', '1/8', '-greyscale'],
  28                          stdin=subprocess.PIPE, stdout=subprocess.PIPE)
  29
  30     out, err = p.communicate(jpeg_data)
  31     # out will be scaled down by 8, ie from 800x600 to 100x75
  32     # we want it down to 8x6, 4x3 or thereabouts
  33     # precision doesn't matter
  34     header, imstring = out.split('255\n', 1)
  35     header = header.split()
  36     size = [int(x) for x in header[1:3]]
  37     im = Image.fromstring("L", size, imstring)
  38     im = stretch(im, (8, 6))
  39     return im.tostring()
  40
  41 def process_dir(dirname, blobname=BLOB_NAME):
  42     fn_re = re.compile(r'(\d{3})-(\d{5}).jpg')
  43
  44     jpegblob = open(blobname, 'w')
  45
  46     frames = []
  47     glob_index = 0
  48
  49     files = sorted(x for x in os.listdir(dirname) if fn_re.match(x))
  50
  51     seq_id = None
  52     frame_counter = count()
  53     for fn in files:
  54         f = open(os.path.join(dirname, fn))
  55         jpeg = f.read()
  56         f.close()
  57         jpegblob.write(jpeg)
  58
  59         frame = Frame()
  60         frame.index = frame_counter.next()
  61         frame.glob_index = glob_index
  62         frame.jpeg_len = len(jpeg)
  63         frame.summary = downscale_pil(jpeg)
  64         frame.successors = [0] * 8
  65
  66         m = fn_re.match(fn)
  67         new_seq_id = m.group(1)
  68         if new_seq_id != seq_id:
  69             seq_id = new_seq_id
  70         elif frames:
  71             prev = frames[-1]
  72             prev.successors[0] = frame.index
  73
  74         frames.append(frame)
  75         glob_index += len(jpeg)
  76
  77
  78     save_frames(frames, INDEX_FILE + '-prelink')
  79     save_frames_text(frames, TEXT_INDEX_FILE + '-prelink')
  80
  81     link_frames(frames)
  82
  83     save_frames(frames, INDEX_FILE)
  84     save_frames_text(frames, TEXT_INDEX_FILE)
  85
  86
  87
  88
  89 process_dir(sys.argv[1])