pygtktalog/src/lib/video.py

"""
    Project: pyGTKtalog
    Description: Gather video file information, make "screenshot" with content
                 of the movie file. Uses external tools like mplayer and
                 ImageMagick tools (montage, convert).
    Type: lib
    Author: Roman 'gryf' Dobosz, gryf73@gmail.com
    Created: 2009-04-04
"""
import os
import shutil
from tempfile import mkdtemp, mkstemp
import math

from misc import float_to_string

class Video(object):
    """Class for retrive midentify script output and put it in dict.
    Usually there is no need for such a detailed movie/clip information.
    Midentify script belongs to mplayer package.
    """

    def __init__(self, filename):
        """Init class instance. Filename of a video file is required."""
        self.filename = filename
        self.tags = {}

        output = os.popen('midentify "%s"' % self.filename).readlines()

        attrs = {'ID_VIDEO_WIDTH': ['width', int],
                 'ID_VIDEO_HEIGHT': ['height', int],
                 'ID_LENGTH': ['length', lambda x: int(x.split(".")[0])],
                 # length is in seconds
                 'ID_DEMUXER': ['container', str],
                 'ID_VIDEO_FORMAT': ['video_format', str],
                 'ID_VIDEO_CODEC': ['video_codec', str],
                 'ID_AUDIO_CODEC': ['audio_codec', str],
                 'ID_AUDIO_FORMAT': ['audio_format', str],
                 'ID_AUDIO_NCH':  ['audio_no_channels', int],}

        for line in output:
            line = line.strip()
            for attr in attrs:
                if attr in line:
                    self.tags[attrs[attr][0]] = \
                        attrs[attr][1](line.replace("%s=" % attr, ""))

        if 'length' in self.tags:
            if self.tags['length'] > 0:
                hours = self.tags['length'] / 3600
                seconds = self.tags['length'] - hours * 3600
                minutes = seconds / 60
                seconds -= minutes * 60
                length_str = "%02d:%02d:%02d" % (hours, minutes, seconds)
                self.tags['duration'] = length_str

    def capture(self, out_width=1024):
        """
        Extract images for given video filename and montage it into one, big
        picture, similar to output from Windows Media Player thing, but without
        captions and time (who need it anyway?).
        Arguments:
            @out_width - width of generated image. If actual image width
                         exceeds this number scale is performed.
        Returns: image filename or None

        NOTE: You should remove returned file manually, or move it in some
        other place, otherwise it stays in filesystem.
        """

        if not (self.tags.has_key('length') or self.tags.has_key('width')):
            return None

        # Calculate number of pictures. Base is equivalent 72 pictures for
        # 1:30:00 movie length
        scale = int(10 * math.log(self.tags['length'], math.e) - 11)
        no_pictures = self.tags['length'] / scale
        if no_pictures > 8:
            # for really short movies
            no_pictures = (no_pictures / 8 ) * 8 # only multiple of 8, please.

        if not no_pictures:
            # movie too short or length is 0
            return None

        if no_pictures < 4:
            no_pictures = 4

        tempdir = mkdtemp()
        file_desc, image_fn = mkstemp()
        os.close(file_desc)
        self.__make_captures(tempdir, no_pictures)
        self.__make_montage(tempdir, image_fn, no_pictures, out_width)

        shutil.rmtree(tempdir)
        return image_fn


    def __make_captures(self, directory, no_pictures):
        """
        Make screens with mplayer into given directory
        Arguments:
            @directory - full output directory name
            @no_pictures - number of pictures to take
        """
        step = float(self.tags['length']/(no_pictures + 1))
        current_time = 0
        for dummy in range(1, no_pictures + 1):
            current_time += step
            time = float_to_string(current_time)
            cmd  = "mplayer \"%s\" -ao null -brightness 0 -hue 0 " \
            "-saturation 0 -contrast 0 -vf-clr -vo jpeg:outdir=\"%s\" -ss %s" \
            " -frames 1 2>/dev/null"
            os.popen(cmd % (self.filename, directory, time)).readlines()

            shutil.move(os.path.join(directory, "00000001.jpg"),
                        os.path.join(directory, "picture_%s.jpg" % time))

    def __make_montage(self, directory, image_fn, no_pictures, out_width):
        """
        Generate one big image from screnshots and optionally resize it.
        Arguments:
            @directory - source directory containing images
            @image_fn - destination final image
            @no_pictures - number of pictures
            @out_width - width of final image to be scaled to.
        """
        scale = False
        row_length = 4
        if no_pictures < 8:
            row_length = 2

        if (self.tags['width'] * row_length) > out_width:
            scale = True
        else:
            for i in [8, 6, 5]:
                if (no_pictures % i) == 0 and \
                   (i * self.tags['width']) <= out_width:
                    row_length = i
                    break

        tile = "%dx%d" % (row_length, no_pictures / row_length)

        _curdir = os.path.abspath(os.path.curdir)
        os.chdir(directory)

        # composite pictures
        # readlines trick will make to wait for process end
        cmd = "montage -tile %s -geometry +2+2 picture_*.jpg montage.jpg"
        os.popen(cmd % tile).readlines()

        # scale it to minimum 'modern' width: 1024
        if scale:
            cmd = "convert -scale %s montage.jpg montage_scaled.jpg"
            os.popen(cmd % out_width).readlines()
            shutil.move(os.path.join(directory, 'montage_scaled.jpg'),
                        image_fn)
        else:
            shutil.move(os.path.join(directory, 'montage.jpg'),
                        image_fn)

        os.chdir(_curdir)


    def __str__(self):
        str_out = ''
        for key in self.tags:
            str_out += "%20s: %s\n" % (key, self.tags[key])
        return str_out