py-ogg2/examples/writ_decoder.py

   1 '''
   2   function: Ogg Writ reference encoder
   3   last mod: $Id: writ_decoder.py,v 1.2 2003/12/01 07:18:51 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 from struct import unpack
  12
  13 def ilog(num) :
  14    for x in range(17) :
  15       if 2**x >= num+1 :
  16          return x
  17    return 0
  18
  19 # Grab 'em pages!
  20 op = ogg2.OggSyncState()
  21 infile = open('test.writ.ogg','r')
  22 while op.input(infile) :
  23    pass
  24 pages = []
  25 while 1 :
  26    page=op.pageout()
  27    if page == None :
  28       break
  29    else :
  30       pages.append(page)
  31
  32 # Churn 'em into packets!
  33 os = ogg2.OggStreamState(pages[0].serialno)
  34 for page in pages :
  35    os.pagein(page)
  36
  37 while 1 :
  38    packet = os.packetout()
  39    if packet == None :
  40       break
  41    else :
  42       ob=ogg2.OggPackBuff(packet)
  43       if ob.read(8)==0 :
  44          if ob.read(32) == 1953067639 :
  45             version = ob.read(8)
  46             print 'Version: %d' % version
  47             gnum = ob.read(32)
  48             gdom = ob.read(32)
  49             print 'Granulerate: %d/%d' % (gnum, gdom)
  50             lscx = ob.read(16)
  51             lscy = ob.read(16)
  52             bitx = ilog(lscx)
  53             bity = ilog(lscy)
  54             totl = (bitx*2)+(bity*2)+4
  55             bitp = ((((totl-1)/8)+1)*8)-totl
  56             lnum = ob.read(8)
  57             langs = []
  58             print 'langs =', lnum
  59             for l in range(lnum+1) :
  60                llen = ob.read(8)
  61                data = ''
  62                for a in range(llen) :
  63                   data = data + chr(ob.read(8))
  64                lname = unicode(data)
  65                llen = ob.read(8)
  66                data = ''
  67                for a in range(llen) :
  68                   data = data + chr(ob.read(8))
  69                ldesc = unicode(data)
  70                langs.append((lname,ldesc))
  71                print 'Language: %s (%s)' % (langs[l][0], langs[l][1])
  72             print ''
  73          else :
  74             print 'Non-Writ Packet?'
  75             continue
  76       else :
  77          print 'Phrase:'
  78          gstart = ob.read(32) + (ob.read(32)*4294967296)
  79          gdurat = ob.read(32)
  80          print '   Time: %d - %d' % (gstart, gstart+gdurat)
  81          locx = ob.read(ilog(lscx))
  82          locy = ob.read(ilog(lscy))
  83          print '   Location: %d,%d' % (locx, locy)
  84          locw = ob.read(ilog(lscx))
  85          loch = ob.read(ilog(lscy))
  86          print '   Size: %d,%d' % (locw, loch)
  87          alix = ob.read(2)
  88          aliy = ob.read(2)
  89          print '   Alignment: %d,%d' % (alix, aliy)
  90          ob.read(bitp)
  91          for l in range(lnum+1) :
  92             tlen = ob.read(8)
  93             data = u''
  94             for a in range(tlen) :
  95                inp = ob.read(8)
  96                if inp == None :
  97                   print 'ERROR: Premature end of packet.'
  98                   break
  99                data = data + unichr(inp)
 100             print (u'   '+langs[l][0]+u': '+data).encode('latin-1')
 101          print ''
 102