decoders/spdif/pd.py

   1 ##
   2 ## This file is part of the libsigrokdecode project.
   3 ##
   4 ## Copyright (C) 2014 Guenther Wenninger <robin@bitschubbser.org>
   5 ##
   6 ## This program is free software; you can redistribute it and/or modify
   7 ## it under the terms of the GNU General Public License as published by
   8 ## the Free Software Foundation; either version 2 of the License, or
   9 ## (at your option) any later version.
  10 ##
  11 ## This program is distributed in the hope that it will be useful,
  12 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 ## GNU General Public License for more details.
  15 ##
  16 ## You should have received a copy of the GNU General Public License
  17 ## along with this program; if not, write to the Free Software
  18 ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  19 ##
  20
  21 import sigrokdecode as srd
  22
  23 class SamplerateError(Exception):
  24     pass
  25
  26 class Decoder(srd.Decoder):
  27     api_version = 2
  28     id = 'spdif'
  29     name = 'S/PDIF'
  30     longname = 'Sony/Philips Digital Interface Format'
  31     desc = 'Serial bus for connecting digital audio devices.'
  32     license = 'gplv2+'
  33     inputs = ['logic']
  34     outputs = ['spdif']
  35     channels = (
  36         {'id': 'data', 'name': 'Data', 'desc': 'Data line'},
  37     )
  38     annotations = (
  39         ('bitrate', 'Bitrate / baudrate'),
  40         ('preamble', 'Preamble'),
  41         ('bits', 'Bits'),
  42         ('aux', 'Auxillary-audio-databits'),
  43         ('samples', 'Audio Samples'),
  44         ('validity', 'Data Valid'),
  45         ('subcode', 'Subcode data'),
  46         ('chan_stat', 'Channnel Status'),
  47         ('parity', 'Parity Bit'),
  48     )
  49     annotation_rows = (
  50         ('info', 'Info', (0, 1, 3, 5, 6, 7, 8)),
  51         ('bits', 'Bits', (2,)),
  52         ('samples', 'Samples', (4,)),
  53     )
  54
  55     def putx(self, ss, es, data):
  56         self.put(ss, es, self.out_ann, data)
  57
  58     def __init__(self, **kwargs):
  59         self.state  = 0
  60         self.olddata = None
  61         self.ss_edge = None
  62         self.first_edge = True
  63         self.pulse_width = 0
  64
  65         self.clocks = []
  66         self.range1 = 0
  67         self.range2 = 0
  68
  69         self.preamble_state = 0
  70         self.preamble = []
  71         self.seen_preamble = False
  72         self.last_preamble = 0
  73
  74         self.first_one = True
  75         self.subframe = []
  76
  77     def start(self):
  78         self.out_ann = self.register(srd.OUTPUT_ANN)
  79
  80     def metadata(self, key, value):
  81         if key == srd.SRD_CONF_SAMPLERATE:
  82             self.samplerate = value
  83
  84     def get_pulse_type(self, pulse):
  85         if self.range1 == 0 or self.range2 == 0:
  86             return -1
  87         if pulse >= self.range2:
  88             return 2
  89         elif pulse >= self.range1:
  90             return 0
  91         else:
  92             return 1
  93
  94     def decode(self, ss, es, data):
  95         if not self.samplerate:
  96             raise SamplerateError('Cannot decode without samplerate.')
  97
  98         for (self.samplenum, pins) in data:
  99             data = pins[0]
 100
 101             # Initialize first self.olddata with the first sample value.
 102             if self.olddata == None:
 103                 self.olddata = data
 104                 continue
 105
 106             # First we need to recover the clock.
 107             if self.olddata == data:
 108                 self.pulse_width += 1
 109             else:
 110                 # Found rising or falling edge.
 111                 if self.first_edge:
 112                     # Throw away first detected edge as it might be mangled data.
 113                     self.first_edge = False
 114                     self.pulse_width = 0
 115                 else:
 116                     if self.state == 0:
 117                         # Find first pulse width.
 118                         if self.pulse_width != 0:
 119                             self.clocks.append(self.pulse_width)
 120                             self.state = 1
 121
 122                     elif self.state == 1:
 123                         # Find second pulse width.
 124                         if self.pulse_width > (self.clocks[0] * 1.3) or self.pulse_width < (self.clocks[0] * 0.7):
 125                             self.clocks.append(self.pulse_width)
 126                             self.state = 2
 127
 128                     elif self.state == 2:
 129                         # Find third pulse width.
 130                         if (self.pulse_width > (self.clocks[0] * 1.3) or self.pulse_width < (self.clocks[0] * 0.7)) \
 131                                 and (self.pulse_width > (self.clocks[1] * 1.3) or self.pulse_width < (self.clocks[1] * 0.7)):
 132                             self.clocks.append(self.pulse_width)
 133                             self.clocks.sort()
 134                             self.range1 = (self.clocks[0] + self.clocks[1]) / 2
 135                             self.range2 = (self.clocks[1] + self.clocks[2]) / 2
 136                             spdif_bitrate = int(self.samplerate / (self.clocks[2] / 1.5))
 137                             self.ss_edge = 0
 138
 139                             self.putx(self.ss_edge, self.samplenum, [0, \
 140                                     ['Signal Bitrate: %d Mbit/s (=> %d kHz)' % \
 141                                     (spdif_bitrate, (spdif_bitrate/ (2 * 32)))]])
 142
 143                             clock_period_nsec = 1000000000 / spdif_bitrate
 144
 145                             self.last_preamble = self.samplenum
 146                             # We are done recovering the clock, now let's decode the data stream.
 147                             self.state = 3
 148
 149                     elif self.state == 3:
 150                         # Decode the stream.
 151                         pulse = self.get_pulse_type(self.pulse_width)
 152
 153                         if self.seen_preamble:
 154                             if pulse == 1 and self.first_one:
 155                                 self.first_one = False
 156                                 self.subframe.append([pulse, self.samplenum - self.pulse_width - 1, self.samplenum])
 157                             elif pulse == 1 and not self.first_one:
 158                                 self.subframe[-1][2] = self.samplenum
 159                                 self.putx(self.subframe[-1][1], self.samplenum, [2, ['1']])
 160                                 self.bitcount += 1
 161                                 self.first_one = True
 162                             else:
 163                                 self.subframe.append([pulse, self.samplenum - self.pulse_width - 1, self.samplenum])
 164                                 self.putx(self.samplenum - self.pulse_width - 1, self.samplenum, [2, ['0']])
 165                                 self.bitcount += 1
 166
 167                             if self.bitcount == 28:
 168                                 aux_audio_data = self.subframe[0:4]
 169                                 sam, sam_rot = '', ''
 170                                 for a in aux_audio_data:
 171                                     sam = sam + str(a[0])
 172                                     sam_rot = str(a[0]) + sam_rot
 173                                 sample = self.subframe[4:24]
 174                                 for s in sample:
 175                                     sam = sam + str(s[0])
 176                                     sam_rot = str(s[0]) + sam_rot
 177                                 validity = self.subframe[24:25]
 178                                 subcode_data = self.subframe[25:26]
 179                                 channel_status = self.subframe[26:27]
 180                                 parity = self.subframe[27:28]
 181
 182                                 self.putx(aux_audio_data[0][1], aux_audio_data[3][2], \
 183                                           [3, ['Aux 0x%x' % int(sam, 2), '0x%x' % int(sam, 2)]])
 184                                 self.putx(sample[0][1], sample[19][2], \
 185                                           [3, ['Sample 0x%x' % int(sam, 2), '0x%x' % int(sam, 2)]])
 186                                 self.putx(aux_audio_data[0][1], sample[19][2], \
 187                                           [4, ['Audio 0x%x' % int(sam_rot, 2), '0x%x' % int(sam_rot, 2)]])
 188                                 if validity[0][0] == 0:
 189                                     self.putx(validity[0][1], validity[0][2], [5, ['V']])
 190                                 else:
 191                                     self.putx(validity[0][1], validity[0][2], [5, ['E']])
 192                                 self.putx(subcode_data[0][1], subcode_data[0][2], [6, ['S: %d' % subcode_data[0][0]]])
 193                                 self.putx(channel_status[0][1], channel_status[0][2], [7, ['C: %d' % channel_status[0][0]]])
 194                                 self.putx(parity[0][1], parity[0][2], [8, ['P: %d' % parity[0][0]]])
 195
 196                                 self.subframe = []
 197                                 self.seen_preamble = False
 198                                 self.bitcount = 0
 199                         else:
 200                             # This is probably the start of a preamble, so go
 201                             # ahead and decode it.
 202                             if pulse == 2:
 203                                 self.preamble.append(self.get_pulse_type(self.pulse_width))
 204                                 self.state = 4 # Decode a preamble.
 205                                 self.ss_edge = self.samplenum - self.pulse_width - 1
 206
 207                     elif self.state == 4:
 208                         if self.preamble_state == 0:
 209                             self.preamble.append(self.get_pulse_type(self.pulse_width))
 210                             self.preamble_state = 1
 211                         elif self.preamble_state == 1:
 212                             self.preamble.append(self.get_pulse_type(self.pulse_width))
 213                             self.preamble_state = 2
 214                         elif self.preamble_state == 2:
 215                             self.preamble.append(self.get_pulse_type(self.pulse_width))
 216                             self.preamble_state = 0
 217                             self.state = 3
 218                             if self.preamble == [2, 0, 1, 0]:
 219                                 self.putx(self.ss_edge, self.samplenum, [1, ['Preamble W', 'W']])
 220                             elif self.preamble == [2, 2, 1, 1]:
 221                                 self.putx(self.ss_edge, self.samplenum, [1, ['Preamble M', 'M']])
 222                             elif self.preamble == [2, 1, 1, 2]:
 223                                 self.putx(self.ss_edge, self.samplenum, [1, ['Preamble B', 'B']])
 224                             else:
 225                                 self.putx(self.ss_edge, self.samplenum, [1, ['Unknown Preamble', 'Unkown Prea.', 'U']])
 226                             self.preamble = []
 227                             self.seen_preamble = True
 228                             self.bitcount = 0
 229                             self.first_one = True
 230
 231                         self.last_preamble = self.samplenum
 232
 233                 self.pulse_width = 0
 234
 235             self.olddata = data
 236