projects / linux-2.6-block.git / blame
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| 2 | HOWTO: Get An Avermedia DVB-T working under Linux | |
| 3 | ______________________________________________ | |
| 4 | ||
| 5 | Table of Contents | |
| 6 | Assumptions and Introduction | |
| 7 | The Avermedia DVB-T | |
| 8 | Getting the card going | |
| 9 | Receiving DVB-T in Australia | |
| 10 | Known Limitations | |
| 11 | Further Update | |
| 12 | ||
| 13 | Assumptions and Introduction | |
| 14 | ||
| 15 | It is assumed that the reader understands the basic structure | |
| 16 | of the Linux Kernel DVB drivers and the general principles of | |
| 17 | Digital TV. | |
| 18 | ||
| 19 | One significant difference between Digital TV and Analogue TV | |
| 20 | that the unwary (like myself) should consider is that, | |
| 21 | although the component structure of budget DVB-T cards are | |
| 22 | substantially similar to Analogue TV cards, they function in | |
| 23 | substantially different ways. | |
| 24 | ||
| 25 | The purpose of an Analogue TV is to receive and display an | |
| 26 | Analogue Television signal. An Analogue TV signal (otherwise | |
| 27 | known as composite video) is an analogue encoding of a | |
| 28 | sequence of image frames (25 per second) rasterised using an | |
| 29 | interlacing technique. Interlacing takes two fields to | |
| 30 | represent one frame. Computers today are at their best when | |
| 31 | dealing with digital signals, not analogue signals and a | |
| 32 | composite video signal is about as far removed from a digital | |
| 33 | data stream as you can get. Therefore, an Analogue TV card for | |
| 34 | a PC has the following purpose: | |
| 35 | ||
| 36 | * Tune the receiver to receive a broadcast signal | |
| 37 | * demodulate the broadcast signal | |
| 38 | * demultiplex the analogue video signal and analogue audio | |
| 39 | signal (note some countries employ a digital audio signal | |
| 40 | embedded within the modulated composite analogue signal - | |
| 41 | NICAM.) | |
| 42 | * digitize the analogue video signal and make the resulting | |
| 43 | datastream available to the data bus. | |
| 44 | ||
| 45 | The digital datastream from an Analogue TV card is generated | |
| 46 | by circuitry on the card and is often presented uncompressed. | |
| 47 | For a PAL TV signal encoded at a resolution of 768x576 24-bit | |
| 48 | color pixels over 25 frames per second - a fair amount of data | |
| 49 | is generated and must be proceesed by the PC before it can be | |
| 50 | displayed on the video monitor screen. Some Analogue TV cards | |
| 51 | for PC's have onboard MPEG2 encoders which permit the raw | |
| 52 | digital data stream to be presented to the PC in an encoded | |
| 53 | and compressed form - similar to the form that is used in | |
| 54 | Digital TV. | |
| 55 | ||
| 56 | The purpose of a simple budget digital TV card (DVB-T,C or S) | |
| 57 | is to simply: | |
| 58 | ||
| 59 | * Tune the received to receive a broadcast signal. | |
| 60 | * Extract the encoded digital datastream from the broadcast | |
| 61 | signal. | |
| 62 | * Make the encoded digital datastream (MPEG2) available to | |
| 63 | the data bus. | |
| 64 | ||
| 65 | The significant difference between the two is that the tuner | |
| 66 | on the analogue TV card spits out an Analogue signal, whereas | |
| 67 | the tuner on the digital TV card spits out a compressed | |
| 68 | encoded digital datastream. As the signal is already | |
| 69 | digitised, it is trivial to pass this datastream to the PC | |
| 70 | databus with minimal additional processing and then extract | |
| 71 | the digital video and audio datastreams passing them to the | |
| 72 | appropriate software or hardware for decoding and viewing. | |
| 73 | _________________________________________________________ | |
| 74 | ||
| 75 | The Avermedia DVB-T | |
| 76 | ||
| 77 | The Avermedia DVB-T is a budget PCI DVB card. It has 3 inputs: | |
| 78 | ||
| 79 | * RF Tuner Input | |
| 80 | * Composite Video Input (RCA Jack) | |
| 81 | * SVIDEO Input (Mini-DIN) | |
| 82 | ||
| 83 | The RF Tuner Input is the input to the tuner module of the | |
| 84 | card. The Tuner is otherwise known as the "Frontend" . The | |
| 85 | Frontend of the Avermedia DVB-T is a Microtune 7202D. A timely | |
| 86 | post to the linux-dvb mailing list ascertained that the | |
| 87 | Microtune 7202D is supported by the sp887x driver which is | |
| 88 | found in the dvb-hw CVS module. | |
| 89 | ||
| 90 | The DVB-T card is based around the BT878 chip which is a very | |
| 91 | common multimedia bridge and often found on Analogue TV cards. | |
| 92 | There is no on-board MPEG2 decoder, which means that all MPEG2 | |
| 93 | decoding must be done in software, or if you have one, on an | |
| 94 | MPEG2 hardware decoding card or chipset. | |
| 95 | _________________________________________________________ | |
| 96 | ||
| 97 | Getting the card going | |
| 98 | ||
| 99 | In order to fire up the card, it is necessary to load a number | |
| 100 | of modules from the DVB driver set. Prior to this it will have | |
| 101 | been necessary to download these drivers from the linuxtv CVS | |
| 102 | server and compile them successfully. | |
| 103 | ||
| 104 | Depending on the card's feature set, the Device Driver API for | |
| 105 | DVB under Linux will expose some of the following device files | |
| 106 | in the /dev tree: | |
| 107 | ||
| 108 | * /dev/dvb/adapter0/audio0 | |
| 109 | * /dev/dvb/adapter0/ca0 | |
| 110 | * /dev/dvb/adapter0/demux0 | |
| 111 | * /dev/dvb/adapter0/dvr0 | |
| 112 | * /dev/dvb/adapter0/frontend0 | |
| 113 | * /dev/dvb/adapter0/net0 | |
| 114 | * /dev/dvb/adapter0/osd0 | |
| 115 | * /dev/dvb/adapter0/video0 | |
| 116 | ||
| 117 | The primary device nodes that we are interested in (at this | |
| 118 | stage) for the Avermedia DVB-T are: | |
| 119 | ||
| 120 | * /dev/dvb/adapter0/dvr0 | |
| 121 | * /dev/dvb/adapter0/frontend0 | |
| 122 | ||
| 123 | The dvr0 device node is used to read the MPEG2 Data Stream and | |
| 124 | the frontend0 node is used to tune the frontend tuner module. | |
| 125 | ||
| 126 | At this stage, it has not been able to ascertain the | |
| 127 | functionality of the remaining device nodes in respect of the | |
| 128 | Avermedia DVBT. However, full functionality in respect of | |
| 129 | tuning, receiving and supplying the MPEG2 data stream is | |
| 130 | possible with the currently available versions of the driver. | |
| 131 | It may be possible that additional functionality is available | |
| 132 | from the card (i.e. viewing the additional analogue inputs | |
| 133 | that the card presents), but this has not been tested yet. If | |
| 134 | I get around to this, I'll update the document with whatever I | |
| 135 | find. | |
| 136 | ||
| 137 | To power up the card, load the following modules in the | |
| 138 | following order: | |
| 139 | ||
| 140 | * insmod dvb-core.o | |
| 141 | * modprobe bttv.o | |
| 142 | * insmod bt878.o | |
| 143 | * insmod dvb-bt8xx.o | |
| 144 | * insmod sp887x.o | |
| 145 | ||
| 146 | Insertion of these modules into the running kernel will | |
| 147 | activate the appropriate DVB device nodes. It is then possible | |
| 148 | to start accessing the card with utilities such as scan, tzap, | |
| 149 | dvbstream etc. | |
| 150 | ||
| 151 | The frontend module sp887x.o, requires an external firmware. | |
| 152 | Please use the command "get_dvb_firmware sp887x" to download | |
| 153 | it. Then copy it to /usr/lib/hotplug/firmware. | |
| 154 | ||
| 155 | Receiving DVB-T in Australia | |
| 156 | ||
| 157 | I have no experience of DVB-T in other countries other than | |
| 158 | Australia, so I will attempt to explain how it works here in | |
| 159 | Melbourne and how this affects the configuration of the DVB-T | |
| 160 | card. | |
| 161 | ||
| 162 | The Digital Broadcasting Australia website has a Reception | |
| 163 | locatortool which provides information on transponder channels | |
| 164 | and frequencies. My local transmitter happens to be Mount | |
| 165 | Dandenong. | |
| 166 | ||
| 167 | The frequencies broadcast by Mount Dandenong are: | |
| 168 | ||
| 169 | Table 1. Transponder Frequencies Mount Dandenong, Vic, Aus. | |
| 170 | Broadcaster Channel Frequency | |
| 171 | ABC VHF 12 226.5 MHz | |
| 172 | TEN VHF 11 219.5 MHz | |
| 173 | NINE VHF 8 191.625 MHz | |
| 174 | SEVEN VHF 6 177.5 MHz | |
| 175 | SBS UHF 29 536.5 MHz | |
| 176 | ||
| 177 | The Scan utility has a set of compiled-in defaults for various | |
| 178 | countries and regions, but if they do not suit, or if you have | |
| 179 | a pre-compiled scan binary, you can specify a data file on the | |
| 180 | command line which contains the transponder frequencies. Here | |
| 181 | is a sample file for the above channel transponders: | |
| 182 | # Data file for DVB scan program | |
| 183 | # | |
| 184 | # C Frequency SymbolRate FEC QAM | |
| 185 | # S Frequency Polarisation SymbolRate FEC | |
| 186 | # T Frequency Bandwidth FEC FEC2 QAM Mode Guard Hier | |
| 187 | T 226500000 7MHz 2/3 NONE QAM64 8k 1/8 NONE | |
| 188 | T 191625000 7MHz 2/3 NONE QAM64 8k 1/8 NONE | |
| 189 | T 219500000 7MHz 2/3 NONE QAM64 8k 1/8 NONE | |
| 190 | T 177500000 7MHz 2/3 NONE QAM64 8k 1/8 NONE | |
| 191 | T 536500000 7MHz 2/3 NONE QAM64 8k 1/8 NONE | |
| 192 | ||
| 193 | The defaults for the transponder frequency and other | |
| 194 | modulation parameters were obtained from www.dba.org.au. | |
| 195 | ||
| 196 | When Scan runs, it will output channels.conf information for | |
| 197 | any channel's transponders which the card's frontend can lock | |
| 198 | onto. (i.e. any whose signal is strong enough at your | |
| 199 | antenna). | |
| 200 | ||
| 201 | Here's my channels.conf file for anyone who's interested: | |
| 202 | ABC HDTV:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:QAM_64 | |
| 203 | :TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:2307:0:560 | |
| 204 | ABC TV Melbourne:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_ | |
| 205 | 4:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:65 | |
| 206 | 0:561 | |
| 207 | ABC TV 2:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:QAM_64 | |
| 208 | :TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:562 | |
| 209 | ABC TV 3:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:QAM_64 | |
| 210 | :TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:563 | |
| 211 | ABC TV 4:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:QAM_64 | |
| 212 | :TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:564 | |
| 213 | ABC DiG Radio:226500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_3_4:Q | |
| 214 | AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:0:2311:56 | |
| 215 | 6 | |
| 216 | TEN Digital:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM | |
| 217 | _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:158 | |
| 218 | 5 | |
| 219 | TEN Digital 1:219500000: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 | 586 | |
| 222 | TEN Digital 2:219500000: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 | 587 | |
| 225 | TEN Digital 3:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:Q | |
| 226 | AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:1 | |
| 227 | 588 | |
| 228 | TEN Digital:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM | |
| 229 | _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:158 | |
| 230 | 9 | |
| 231 | TEN Digital 4:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:Q | |
| 232 | AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:1 | |
| 233 | 590 | |
| 234 | TEN Digital:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM | |
| 235 | _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:159 | |
| 236 | 1 | |
| 237 | TEN HD:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM_64:T | |
| 238 | RANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:514:0:1592 | |
| 239 | TEN Digital:219500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM | |
| 240 | _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:650:159 | |
| 241 | 3 | |
| 242 | Nine Digital:191625000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QA | |
| 243 | M_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:513:660:10 | |
| 244 | 72 | |
| 245 | Nine Digital HD:191625000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2 | |
| 246 | :QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:0:1 | |
| 247 | 073 | |
| 248 | Nine Guide:191625000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_3_4:FEC_1_2:QAM_ | |
| 249 | 64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:514:670:1074 | |
| 250 | 7 Digital:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM_6 | |
| 251 | 4:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:769:770:1328 | |
| 252 | 7 Digital 1:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM | |
| 253 | _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:769:770:1329 | |
| 254 | 7 Digital 2:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM | |
| 255 | _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:769:770:1330 | |
| 256 | 7 Digital 3:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM | |
| 257 | _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:769:770:1331 | |
| 258 | 7 HD Digital:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QA | |
| 259 | M_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:833:834:133 | |
| 260 | 2 | |
| 261 | 7 Program Guide:177500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3 | |
| 262 | :QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:865:866: | |
| 263 | 1334 | |
| 264 | SBS HD:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM_64:T | |
| 265 | RANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:102:103:784 | |
| 266 | SBS DIGITAL 1:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:Q | |
| 267 | AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:161:81:785 | |
| 268 | SBS DIGITAL 2:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:Q | |
| 269 | AM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:162:83:786 | |
| 270 | SBS EPG:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM_64: | |
| 271 | TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:163:85:787 | |
| 272 | SBS RADIO 1:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM | |
| 273 | _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:0:201:798 | |
| 274 | SBS RADIO 2:536500000:INVERSION_OFF:BANDWIDTH_7_MHZ:FEC_2_3:FEC_2_3:QAM | |
| 275 | _64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_8:HIERARCHY_NONE:0:202:799 | |
| 276 | _________________________________________________________ | |
| 277 | ||
| 278 | Known Limitations | |
| 279 | ||
| 280 | At present I can say with confidence that the frontend tunes | |
| 281 | via /dev/dvb/adapter{x}/frontend0 and supplies an MPEG2 stream | |
| 282 | via /dev/dvb/adapter{x}/dvr0. I have not tested the | |
| 283 | functionality of any other part of the card yet. I will do so | |
| 284 | over time and update this document. | |
| 285 | ||
| 286 | There are some limitations in the i2c layer due to a returned | |
| 287 | error message inconsistency. Although this generates errors in | |
| 288 | dmesg and the system logs, it does not appear to affect the | |
| 289 | ability of the frontend to function correctly. | |
| 290 | _________________________________________________________ | |
| 291 | ||
| 292 | Further Update | |
| 293 | ||
| 294 | dvbstream and VideoLAN Client on windows works a treat with | |
| 295 | DVB, in fact this is currently serving as my main way of | |
| 296 | viewing DVB-T at the moment. Additionally, VLC is happily | |
| 297 | decoding HDTV signals, although the PC is dropping the odd | |
| 298 | frame here and there - I assume due to processing capability - | |
| 299 | as all the decoding is being done under windows in software. | |
| 300 | ||
| 301 | Many thanks to Nigel Pearson for the updates to this document | |
| 302 | since the recent revision of the driver. | |
| 303 | ||
| 304 | January 29th 2004 |