Python .mv -> images script

Hi,

   Just thought I'd drop this script on you all.  It converts .mv files
that are motion jpegs to <some other image format> suitable for a
quick:

ffmpeg -i frames_%04d.jpeg -o a.mpeg

   I just wrote this up this week and any feedback would be greatly
appreciated.  You will need to have PIL installed:

http://www.pythonware.com/products/pil/

Kind Regards,
Jeremy

====== sgi2foo.py ======

''' File:      sgi2foo.py
    Purpose:   Script for converting SGI .mv motion jpegs to something
else
    Author:    Jeremy Stark, jeremy@[EMAIL PROTECTED]
    Copyright: 2006 Jeremy Stark, Licensed under the GPL version 2 or
later
'''
im****t sys, os, types, getopt
im****t Image
from cStringIO im****t StringIO

def sgiExtract( file                 # Path string to the sgi movie
file
              , dest_dir             # Path to dump the images to
              , dest_name = 'frame_' # Base File name to use for images
              , extension = '.jpeg'  # Extension type (.jpeg or .png is
good)
              , size      = None     # Tuple (Width, Height) to scale
images to
              , optimized = True     # Use image codec optimizations
              , quality   = 99):     # JPEG quality setting
    ''' Decomposes an SGI format movie file to seperate image files
    '''
    header = sgiHeaderInfo(file)
    fptr = open(file, mode='r')
    data = fptr.read()
    fptr.close()
    images = data.split('\xFF\xD8\xFF\xE0')
    outfile = dest_dir + os.sep + dest_name + '%s' + extension

    if header['INTERLACING'] != '2':
        images =[Image.open(StringIO('\xFF\xD8\xFF\xE0'))+i for i in
images[1:]]
        return _saveImages(images, outfile, size, quality, optimized)

    delaced = []
    for i in range(1, len(images), 2):
        tmp = deinterlace(
Image.open(StringIO('\xFF\xD8\xFF\xE0'+images[i]))
                         ,
Image.open(StringIO('\xFF\xD8\xFF\xE0'+images[i+1])))
        delaced.append(tmp)
    return _saveImages(delaced, outfile, size, quality, optimized)

def _saveImages(images, outfile, size=None, quality=99,
optimized=True):
    ''' Helper method to save off the images
    '''
    c = 1
    pad = len(str(len(images)))
    for i in images:
        if size:
            i = i.resize(size)

i.save(outfile%(str(c).zfill(pad),),quality=quality,optimized=optimized)
        c += 1
    return len(images)

def deinterlace(i1, i2):
    image = ''
    bbox = i1.getbbox()
    line_width = bbox[2] * 3 # R,G,B pixel values = 3x line width
    s1 = i1.tostring()
    s2 = i2.tostring()
    for c in range(0, len(s1), line_width):
        image += s2[c:c+line_width]
        image += s1[c:c+line_width]
    return Image.fromstring('RGB', (bbox[2], bbox[3]*2), image)

def sgiPreviewFrame(file, frame=1):
    ''' Return a single frame
    '''
    fptr = open(file, mode='r')
    data = fptr.read()
    fptr.close()
    header = sgiHeaderInfo(file)
    images = data.split('\xFF\xD8\xFF\xE0')
    if header['INTERLACING'] == '2':
        return
deinterlace(Image.open(StringIO('\xFF\xD8\xFF\xE0'+images[frame]))

,Image.open(StringIO('\xFF\xD8\xFF\xE0'+images[frame+1])))
    return Image.open(StringIO('\xFF\xD8\xFF\xE0'+images[frame]))

def sgiHeaderInfo(file):
    ''' Return a dictionary of header info extracted from <file>
    '''
    fields = { '__NUM_I_TRACKS' : None
             , '__NUM_A_TRACKS' : None
             , 'LOOP_MODE'      : None
             , 'OPTIMIZED'      : None
             , 'NUM_LOOPS'      : None
             , 'WIDTH'          : None
             , 'COMPRESSION'    : None
             , 'ORIENTATION'    : None
             , 'Q_TEM****AL'     : None
             , 'HEIGHT'         : None
             , '__DIR_COUNT'    : None
             , 'INTERLACING'    : None
             , 'FPS'            : None
             , 'Q_SPATIAL'      : None
             , 'PACKING'        : None
             }
    file = open(file, mode='r')
    data = file.read(500)
    file.close()

    for field in fields.keys():
        start = data.find(field) + 20
        length = ord(data[data.find(field) + 19])
        fields[field] = data[start:start+length-1]
    return fields

def usage():
    print '''
sgi2foo.py : Copyright 2006, Jeremy Stark, Released under the GPL

Usage:

python sgi2foo.py -i themovie.mv -o /out/dir -O -q 99 -w 720 -h 496

-i   : The input movie
-o   : The output directory to dump all the images to
-q   : JPEG quality setting
-O   : Optimize flag (tells the codec to optimize images, whatever that
means)
-w   : Force output width, ignore if you want the original size
-h   : Force output height.  Required if you specified -w
'''

def main():
    opts, pargs = getopt.getopt(sys.argv[1:], 'Oi:o:q:h:w:',[])
    optimized = False
    file = outfile = height = width = size = None
    quality = 99

    for opt in opts:
        if opt[0] == '-O':
            optimized = True
        if opt[0] == '-i':
            file = opt[1]
        if opt[0] == '-o':
            outdir = opt[1]
        if opt[0] == '-q':
            quality = opt[1]
        if opt[0] == '-h':
            height = opt[1]
        if opt[0] == '-w':
            width = opt[1]

    if height and width:
        size = (int(width), int(height))

    sgiExtract(file, outdir, quality=quality, optimized=optimized,
size=size)

if __name__ == '__main__':
    if len(sys.argv) == 1:
        usage()
    else:
        main()

===== End script ====