Documentation/dvb/avermedia.txt

   1 HOWTO: Get An Avermedia DVB-T working under Linux
   2            ______________________________________________
   3
   4    Table of Contents
   5    Assumptions and Introduction
   6    The Avermedia DVB-T
   7    Getting the card going
   8    Receiving DVB-T in Australia
   9    Known Limitations
  10    Further Update
  11
  12 Assumptions and Introduction
  13
  14    It  is assumed that the reader understands the basic structure
  15    of  the Linux Kernel DVB drivers and the general principles of
  16    Digital TV.
  17
  18    One  significant difference between Digital TV and Analogue TV
  19    that  the  unwary  (like  myself)  should  consider  is  that,
  20    although  the  component  structure  of budget DVB-T cards are
  21    substantially  similar  to Analogue TV cards, they function in
  22    substantially different ways.
  23
  24    The  purpose  of  an  Analogue TV is to receive and display an
  25    Analogue  Television  signal. An Analogue TV signal (otherwise
  26    known  as  composite  video)  is  an  analogue  encoding  of a
  27    sequence  of  image frames (25 per second) rasterised using an
  28    interlacing   technique.   Interlacing  takes  two  fields  to
  29    represent  one  frame.  Computers today are at their best when
  30    dealing  with  digital  signals,  not  analogue  signals and a
  31    composite  video signal is about as far removed from a digital
  32    data stream as you can get. Therefore, an Analogue TV card for
  33    a PC has the following purpose:
  34
  35      * Tune the receiver to receive a broadcast signal
  36      * demodulate the broadcast signal
  37      * demultiplex  the  analogue video signal and analogue audio
  38        signal  (note some countries employ a digital audio signal
  39        embedded  within the modulated composite analogue signal -
  40        NICAM.)
  41      * digitize  the analogue video signal and make the resulting
  42        datastream available to the data bus.
  43
  44    The  digital  datastream from an Analogue TV card is generated
  45    by  circuitry on the card and is often presented uncompressed.
  46    For  a PAL TV signal encoded at a resolution of 768x576 24-bit
  47    color pixels over 25 frames per second - a fair amount of data
  48    is  generated and must be processed by the PC before it can be
  49    displayed  on the video monitor screen. Some Analogue TV cards
  50    for  PCs  have  onboard  MPEG2  encoders  which permit the raw
  51    digital  data  stream  to be presented to the PC in an encoded
  52    and  compressed  form  -  similar  to the form that is used in
  53    Digital TV.
  54
  55    The  purpose of a simple budget digital TV card (DVB-T,C or S)
  56    is to simply:
  57
  58      * Tune the received to receive a broadcast signal.
  59      * Extract  the encoded digital datastream from the broadcast
  60        signal.
  61      * Make  the  encoded digital datastream (MPEG2) available to
  62        the data bus.
  63
  64    The  significant  difference between the two is that the tuner
  65    on  the analogue TV card spits out an Analogue signal, whereas
  66    the  tuner  on  the  digital  TV  card  spits out a compressed
  67    encoded   digital   datastream.   As  the  signal  is  already
  68    digitised,  it  is  trivial  to pass this datastream to the PC
  69    databus  with  minimal  additional processing and then extract
  70    the  digital  video  and audio datastreams passing them to the
  71    appropriate software or hardware for decoding and viewing.
  72      _________________________________________________________
  73
  74 The Avermedia DVB-T
  75
  76    The Avermedia DVB-T is a budget PCI DVB card. It has 3 inputs:
  77
  78      * RF Tuner Input
  79      * Composite Video Input (RCA Jack)
  80      * SVIDEO Input (Mini-DIN)
  81
  82    The  RF  Tuner  Input  is the input to the tuner module of the
  83    card.  The  Tuner  is  otherwise known as the "Frontend" . The
  84    Frontend of the Avermedia DVB-T is a Microtune 7202D. A timely
  85    post  to  the  linux-dvb  mailing  list  ascertained  that the
  86    Microtune  7202D  is  supported  by the sp887x driver which is
  87    found in the dvb-hw CVS module.
  88
  89    The  DVB-T card is based around the BT878 chip which is a very
  90    common multimedia bridge and often found on Analogue TV cards.
  91    There is no on-board MPEG2 decoder, which means that all MPEG2
  92    decoding  must  be done in software, or if you have one, on an
  93    MPEG2 hardware decoding card or chipset.
  94      _________________________________________________________
  95
  96 Getting the card going
  97
  98    In order to fire up the card, it is necessary to load a number
  99    of modules from the DVB driver set. Prior to this it will have
 100    been  necessary to download these drivers from the linuxtv CVS
 101    server and compile them successfully.
 102
 103    Depending on the card's feature set, the Device Driver API for
 104    DVB under Linux will expose some of the following device files
 105    in the /dev tree:
 106
 107      * /dev/dvb/adapter0/audio0
 108      * /dev/dvb/adapter0/ca0
 109      * /dev/dvb/adapter0/demux0
 110      * /dev/dvb/adapter0/dvr0
 111      * /dev/dvb/adapter0/frontend0
 112      * /dev/dvb/adapter0/net0
 113      * /dev/dvb/adapter0/osd0
 114      * /dev/dvb/adapter0/video0
 115
 116    The  primary  device  nodes that we are interested in (at this
 117    stage) for the Avermedia DVB-T are:
 118
 119      * /dev/dvb/adapter0/dvr0
 120      * /dev/dvb/adapter0/frontend0
 121
 122    The dvr0 device node is used to read the MPEG2 Data Stream and
 123    the frontend0 node is used to tune the frontend tuner module.
 124
 125    At  this  stage,  it  has  not  been  able  to  ascertain  the
 126    functionality  of the remaining device nodes in respect of the
 127    Avermedia  DVBT.  However,  full  functionality  in respect of
 128    tuning,  receiving  and  supplying  the  MPEG2  data stream is
 129    possible  with the currently available versions of the driver.
 130    It  may be possible that additional functionality is available
 131    from  the  card  (i.e.  viewing the additional analogue inputs
 132    that  the card presents), but this has not been tested yet. If
 133    I get around to this, I'll update the document with whatever I
 134    find.
 135
 136    To  power  up  the  card,  load  the  following modules in the
 137    following order:
 138
 139      * modprobe bttv (normally loaded automatically)
 140      * modprobe dvb-bt8xx (or place dvb-bt8xx in /etc/modules)
 141
 142    Insertion  of  these  modules  into  the  running  kernel will
 143    activate the appropriate DVB device nodes. It is then possible
 144    to start accessing the card with utilities such as scan, tzap,
 145    dvbstream etc.
 146
 147    The frontend module sp887x.o, requires an external   firmware.
 148    Please use  the  command "get_dvb_firmware sp887x" to download
 149    it. Then copy it to /usr/lib/hotplug/firmware or /lib/firmware/
 150    (depending on configuration of firmware hotplug).
 151
 152 Receiving DVB-T in Australia
 153
 154    I  have  no  experience of DVB-T in other countries other than
 155    Australia,  so  I will attempt to explain how it works here in
 156    Melbourne  and how this affects the configuration of the DVB-T
 157    card.
 158
 159    The  Digital  Broadcasting  Australia  website has a Reception
 160    locatortool which provides information on transponder channels
 161    and  frequencies.  My  local  transmitter  happens to be Mount
 162    Dandenong.
 163
 164    The frequencies broadcast by Mount Dandenong are:
 165
 166    Table 1. Transponder Frequencies Mount Dandenong, Vic, Aus.
 167    Broadcaster Channel Frequency
 168    ABC         VHF 12  226.5 MHz
 169    TEN         VHF 11  219.5 MHz
 170    NINE        VHF 8   191.625 MHz
 171    SEVEN       VHF 6   177.5 MHz
 172    SBS         UHF 29  536.5 MHz
 173
 174    The Scan utility has a set of compiled-in defaults for various
 175    countries and regions, but if they do not suit, or if you have
 176    a pre-compiled scan binary, you can specify a data file on the
 177    command  line which contains the transponder frequencies. Here
 178    is a sample file for the above channel transponders:
 179 # Data file for DVB scan program
 180 #
 181 # C Frequency SymbolRate FEC QAM
 182 # S Frequency Polarisation SymbolRate FEC
 183 # T Frequency Bandwidth FEC FEC2 QAM Mode Guard Hier
 184 T 226500000 7MHz 2/3 NONE QAM64 8k 1/8 NONE
 185 T 191625000 7MHz 2/3 NONE QAM64 8k 1/8 NONE
 186 T 219500000 7MHz 2/3 NONE QAM64 8k 1/8 NONE
 187 T 177500000 7MHz 2/3 NONE QAM64 8k 1/8 NONE
 188 T 536500000 7MHz 2/3 NONE QAM64 8k 1/8 NONE
 189
 190    The   defaults   for   the  transponder  frequency  and  other
 191    modulation parameters were obtained from www.dba.org.au.
 192
 193    When  Scan  runs, it will output channels.conf information for
 194    any  channel's transponders which the card's frontend can lock
 195    onto.  (i.e.  any  whose  signal  is  strong  enough  at  your
 196    antenna).
 197
 198    Here's my channels.conf file for anyone who's interested:
 199 ABC HDTV:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:QAM_64
 200 :TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:2307:0:560
 201 ABC TV Melbourne:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_
 202 4:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:65
 203 0:561
 204 ABC TV 2:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:QAM_64
 205 :TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:562
 206 ABC TV 3:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:QAM_64
 207 :TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:563
 208 ABC TV 4:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:QAM_64
 209 :TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:564
 210 ABC DiG Radio:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:Q
 211 AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:0:2311:56
 212 6
 213 TEN Digital:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM
 214 _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:158
 215 5
 216 TEN Digital 1:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:Q
 217 AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:1
 218 586
 219 TEN Digital 2:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:Q
 220 AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:1
 221 587
 222 TEN Digital 3:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:Q
 223 AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:1
 224 588
 225 TEN Digital:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM
 226 _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:158
 227 9
 228 TEN Digital 4:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:Q
 229 AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:1
 230 590
 231 TEN Digital:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM
 232 _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:159
 233 1
 234 TEN HD:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM_64:T
 235 RANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:514:0:1592
 236 TEN Digital:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM
 237 _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:159
 238 3
 239 Nine Digital:191625000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QA
 240 M_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:513:660:10
 241 72
 242 Nine Digital HD:191625000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2
 243 :QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:0:1
 244 073
 245 Nine Guide:191625000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM_
 246 64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:514:670:1074
 247 7 Digital:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM_6
 248 4:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:769:770:1328
 249 7 Digital 1:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM
 250 _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:769:770:1329
 251 7 Digital 2:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM
 252 _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:769:770:1330
 253 7 Digital 3:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM
 254 _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:769:770:1331
 255 7 HD Digital:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QA
 256 M_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:833:834:133
 257 2
 258 7 Program Guide:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3
 259 :QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:865:866:
 260 1334
 261 SBS HD:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM_64:T
 262 RANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:102:103:784
 263 SBS DIGITAL 1:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:Q
 264 AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:161:81:785
 265 SBS DIGITAL 2:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:Q
 266 AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:162:83:786
 267 SBS EPG:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM_64:
 268 TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:163:85:787
 269 SBS RADIO 1:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM
 270 _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:0:201:798
 271 SBS RADIO 2:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM
 272 _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:0:202:799
 273      _________________________________________________________
 274
 275 Known Limitations
 276
 277    At  present  I can say with confidence that the frontend tunes
 278    via /dev/dvb/adapter{x}/frontend0 and supplies an MPEG2 stream
 279    via   /dev/dvb/adapter{x}/dvr0.   I   have   not   tested  the
 280    functionality  of any other part of the card yet. I will do so
 281    over time and update this document.
 282
 283    There  are some limitations in the i2c layer due to a returned
 284    error message inconsistency. Although this generates errors in
 285    dmesg  and  the  system logs, it does not appear to affect the
 286    ability of the frontend to function correctly.
 287      _________________________________________________________
 288
 289 Further Update
 290
 291    dvbstream  and  VideoLAN  Client on windows works a treat with
 292    DVB,  in  fact  this  is  currently  serving as my main way of
 293    viewing  DVB-T  at  the  moment.  Additionally, VLC is happily
 294    decoding  HDTV  signals,  although  the PC is dropping the odd
 295    frame here and there - I assume due to processing capability -
 296    as all the decoding is being done under windows in software.
 297
 298    Many  thanks to Nigel Pearson for the updates to this document
 299    since the recent revision of the driver.
 300
 301    February 14th 2006