Source Code for Module flumotion.component.encoders.vorbis.vorbisutils

 1  # -*- Mode: Python -*- 
 2  # vi:si:et:sw=4:sts=4:ts=4 
 3  # 
 4  # Flumotion - a streaming media server 
 5  # Copyright (C) 2004,2005,2006,2007 Fluendo, S.L. (www.fluendo.com). 
 6  # All rights reserved. 
 7   
 8  # This file may be distributed and/or modified under the terms of 
 9  # the GNU General Public License version 2 as published by 
10  # the Free Software Foundation. 
11  # This file is distributed without any warranty; without even the implied 
12  # warranty of merchantability or fitness for a particular purpose. 
13  # See "LICENSE.GPL" in the source distribution for more information. 
14   
15  # Licensees having purchased or holding a valid Flumotion Advanced 
16  # Streaming Server license may use this file in accordance with the 
17  # Flumotion Advanced Streaming Server Commercial License Agreement. 
18  # See "LICENSE.Flumotion" in the source distribution for more information. 
19   
20  # Headers in this file shall remain intact. 
21   
22  __version__ = "$Rev: 5969 $" 
23   
24 -def get_preferred_sample_rate (maxrate): 
25      """ Get the preferred 'standard' sample rate not exceeded maxrate""" 
26      rates = [192000, 96000, 48000, 44100, 32000, 34000, 22050, 16000, 12000, 
27               11025, 8000] 
28   
29      for rate in rates: 
30          if rate <= maxrate: 
31              return rate 
32   
33      return 8000 
34   
35 -def get_max_sample_rate(bitrate, channels): 
36      # maybe better in a hashtable/associative array? 
37      # ZAHEER: these really are "magic" limits that i found by trial and 
38      # error used 
39      # by libvorbis's encoder to determine what maximum samplerate it 
40      # accepts for a bitrate, numchannels combo 
41      # THOMAS: strangely enough they don't seem to be easily extractable from 
42      # vorbis/lib/modes/setup_*.h 
43      # might make sense to figure this out once and for all and verify 
44      # GStreamer's behaviour as well 
45      if channels == 2: 
46          if bitrate >= 45000: 
47              retval = 50000 
48          elif bitrate >= 40000: 
49              retval = 40000 
50          elif bitrate >= 30000: 
51              retval = 26000 
52          elif bitrate >= 24000: 
53              retval = 19000 
54          elif bitrate >= 16000: 
55              retval = 15000 
56          elif bitrate >= 12000: 
57              retval = 9000 
58          else: 
59              retval = -1 
60   
61      elif channels == 1: 
62          if bitrate >= 32000: 
63              retval = 50000 
64          elif bitrate >= 24000: 
65              retval = 40000 
66          elif bitrate >= 16000: 
67              retval = 26000 
68          elif bitrate >= 12000: 
69              retval = 15000 
70          elif bitrate >= 8000: 
71              retval = 9000 
72          else: 
73              retval = -1 
74   
75      return retval 
76