py-ogg2/examples/writ_encoder.py

   1 '''
   2   function: Ogg Writ 1.2 reference encoder
   3   last mod: $Id: writ_encoder.py,v 1.2 2004/02/24 06:31:49 arc Exp $
   4
   5 This is an example for how py-ogg2 can be used to rapidly design a new
   6 Ogg codec or test an existing codec's specifications for accuracy.
   7
   8 '''
   9
  10 import ogg2
  11 import struct
  12 import random
  13
  14 class BitPacker :
  15    def __init__(self) :
  16       self.pb = ogg2.OggPackBuff()
  17
  18    def uniwrite(self,ustring) :
  19       total = 0
  20       output=[]
  21       for pos in range(len(ustring)) :
  22          value = ord(ustring[pos])
  23          if value < 256 :
  24             size = 8
  25          elif value < 65536 :
  26             size = 16
  27          elif value < 16777216 :
  28             size = 24
  29          else :
  30             size = 32
  31          total = total + (size/8)
  32          output.append((value,size))
  33       if total>255 :
  34          raise('ValueError: Unicode must be no greater than 255 bytes long')
  35       self.pb.write(total,8)
  36       for char in output :
  37          self.pb.write(char[0],char[1])
  38
  39    def write(self,value,size) :
  40       if size>32 :
  41          hi=value/4294967296
  42          lo=value-(hi*4294967296)
  43          self.pb.write(lo,32)
  44          self.pb.write(hi,size-32)
  45       else :
  46          self.pb.write(value,size)
  47
  48    def export(self) :
  49       return self.pb.packetout()
  50
  51    def reset(self) :
  52       self.pb = ogg2.OggPackBuff()
  53       # return self.pb.reset()
  54
  55 class OggStream :
  56    def __init__(self) :
  57       self.os = ogg2.OggStreamState(random.randrange(2**24))
  58       self.os.setmode(ogg2.Ogg_Discont)
  59       self.oy = ogg2.OggSyncState()
  60       self.fd = open('test.writ.ogg','w')
  61       self.pn = 0
  62
  63    def packetin(self, packet, end_granule=0) :
  64       packet.packetno = self.pn
  65       packet.end_granule = end_granule
  66       if self.pn == 0 :
  67          packet.bos = 1
  68       else :
  69          packetno = self.packet.packetno
  70          self.os.packetin(self.packet)
  71          if self.pn != 2 :
  72             self.flush()
  73       self.packet = packet
  74       self.pn = self.pn + 1
  75
  76    def flush(self) :
  77       page = self.os.flush()
  78       if page != None :
  79          self.oy.pagein(page)
  80          output = '.'
  81          while len(output)!= 0 :
  82             output = self.oy.read(4096)
  83             self.fd.write(output)
  84
  85    def close(self) :
  86       self.packet.eos = 1
  87       self.os.packetin(self.packet)
  88       self.flush()
  89       self.fd.close()
  90
  91
  92 def ilog(num) :
  93    for x in range(17) :
  94       if 2**x >= num+1 :
  95          return x
  96    return 0
  97
  98
  99 gnum = 1
 100 gden = 1
 101
 102 langs=(('en','English'),('es','Spanish'))
 103
 104 # winds: location_x, location_y, width, height, alignment_x, alignment_y
 105 sclx = 4000
 106 scly = 270
 107 bitx = ilog(sclx)
 108 bity = ilog(scly)
 109 totl = (bitx*2)+(bity*2)+4
 110 bitp = ((((totl-1)/8)+1)*8)-totl
 111 winds=((1,2,3,1,3,3),(5,6,7,1,3,3))
 112
 113 # texts: start, duration, lang(s), wind
 114 texts=((05,10, ( u'Hello World!' ,
 115                  u'Hola, Mundo!' ), 0),
 116        (12,15, ( u'It\'s a beautiful day to be born.' ,
 117                  u'Es un d\N{LATIN SMALL LETTER I WITH ACUTE}'+\
 118                  u'a hermoso para que se llevar'+\
 119                  u'\N{LATIN SMALL LETTER A WITH ACUTE}.' ), 1) )
 120
 121 bp = BitPacker()
 122 os = OggStream()
 123
 124 # Start with Header 0
 125 bp.write(0,8)                           # header packet 0
 126 bp.write(1953067639,32)                 # "writ"
 127 bp.write(1,8)                           # version = 1
 128 bp.write(2,8)                           # subversion = 2
 129 bp.write(gnum,32)                       # granulerate_numerator
 130 bp.write(gden,32)                       # granulerate_denominator
 131 os.packetin(bp.export())
 132 bp.reset()
 133
 134 # Start with Header 1
 135 bp.write(1,8)                           # header packet 1
 136 bp.write(1953067639,32)                 # "writ"
 137 bp.write(len(langs)-1,8)                # num_languages
 138 for lang in langs:
 139    bp.uniwrite(lang[0])                 # lang_name length, string
 140    bp.uniwrite(lang[1])                 # lang_desc length, string
 141 os.packetin(bp.export())
 142 bp.reset()
 143
 144 # Start with Header 1
 145 bp.write(2,8)                           # header packet 2
 146 bp.write(1953067639,32)                 # "writ"
 147 bp.write(sclx,16)                       # location_scale_x
 148 bp.write(scly,16)                       # location_scale_y
 149 bp.write(len(winds),8)                  # num_windows
 150 for win in winds:
 151    bp.write(win[0],bitx)                # location_x
 152    bp.write(win[1],bity)                # location_x
 153    bp.write(win[2],bitx)                # location_width
 154    bp.write(win[3],bity)                # location_height
 155    bp.write(win[4],2)                   # alignment_x
 156    bp.write(win[5],2)                   # alignment_y
 157 os.packetin(bp.export())
 158 bp.reset()
 159
 160 for text in texts:                      # - Each Phrase -
 161    bp.write(255,8)                      # data packet
 162    bp.write(text[0],64)                 # granule_start
 163    bp.write(text[1],32)                 # granule_duration
 164    for lang in range(len(langs)):
 165       bp.uniwrite(text[2][lang])        # text length, string
 166    if len(winds) > 1 :                  # only if we need to specify
 167       bp.write(text[3],8)               # window_id
 168    os.packetin(bp.export(), text[0])
 169    bp.reset()
 170
 171 os.close()
 172