# Copyright (c) 2007, Kundan Singh. All rights reserved. See LICENSE for details.
This file implements RFC3551 (RTP AVP)
'''
Define the RTP static payload types as per RFC 3551. type and desc are two main functions.

>>> print type('GSM/8000')
3
>>> print desc(3)
('GSM', 8000, 1, 3, 'GSM/8000')

>>> for x in range(0, len(_types)):
...    name, rate, count, pt, d = desc(x)
...    assert(pt == x)
...    if d: assert(x == type(d))
...    if d: print '%d=>%s'%(pt, d),     
0=>PCMU/8000 3=>GSM/8000 4=>G723/8000 5=>DVI4/8000 6=>DVI4/16000 7=>LPC/8000 8=>PCMA/8000 9=>G722/8000 10=>L16/44100/2 11=>L16/44100 12=>QCELP/8000 13=>CN/8000 14=>MPA/90000 15=>G728/8000 16=>DVI4/11025 17=>DVI4/22050 18=>G729/8000 25=>CelB/90000 26=>JPEG/90000 28=>nv/90000 31=>H261/90000 32=>MPV/90000 33=>MP2T/90000 34=>H263/90000
'''

# static types: arranged in rows 0-5, 6-10, 11-15, ...
_types = ["PCMU/8000/1", None, None, "GSM/8000/1", "G723/8000/1", "DVI4/8000/1", \
  "DVI4/16000/1", "LPC/8000/1", "PCMA/8000/1", "G722/8000/1", "L16/44100/2",     \
  "L16/44100/1", "QCELP/8000/1", "CN/8000/1", "MPA/90000/1", "G728/8000/1",      \
  "DVI4/11025/1", "DVI4/22050/1", "G729/8000/1", None, None,                     \
  None, None, None, None, "CelB/90000/1",                                        \
  "JPEG/90000/1",  None, "nv/90000/1", None, None,                               \
  "H261/90000/1", "MPV/90000/1", "MP2T/90000/1", "H263/90000/1"]

def _type2desc(t):
    if _types[t]:
        name, srate, scount = _types[t].split('/')
        return (name, int(srate), int(scount), t, name + '/' + srate + ('' if scount == '1' else '/' + scount))
    else:
        return (None, None, None, t, None)

_desc   = map(_type2desc, range(0, len(_types))) 
_lowers = [(x and x.lower() or None) for x in _types]

# return the type (int) for the description ('name/rate' or 'name/rate/count') or 
# -1 if not found.
type = lambda x:  _lowers.index(x.lower()) if x and (x.lower() in _lowers) \
          else ((_lowers.index(x.lower()+'/1') if x and ((x.lower()+'/1') in _lowers) else -1))

# return the description ('name', rate, count, pt, 'name/rate/count') for the type (int), or 
# tuple (None, None, None, pt, None) if not found or not defined.
desc = lambda x: _desc[x] if x >=0 and x < len(_desc) else (None, None, None, x, None)

if __name__ == '__main__':
    import doctest
    doctest.testmod()