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diff --git a/Documentation/admin-guide/media/dvb_intro.rst b/Documentation/admin-guide/media/dvb_intro.rst new file mode 100644 index 0000000000..44eac9b3be --- /dev/null +++ b/Documentation/admin-guide/media/dvb_intro.rst @@ -0,0 +1,616 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================== +Using the Digital TV Framework +============================== + +Introduction +~~~~~~~~~~~~ + +One significant difference between Digital TV and Analogue TV that the +unwary (like myself) should consider is that, although the component +structure of DVB-T cards are substantially similar to Analogue TV cards, +they function in substantially different ways. + +The purpose of an Analogue TV is to receive and display an Analogue +Television signal. An Analogue TV signal (otherwise known as composite +video) is an analogue encoding of a sequence of image frames (25 frames +per second in Europe) rasterised using an interlacing technique. +Interlacing takes two fields to represent one frame. Therefore, an +Analogue TV card for a PC has the following purpose: + +* Tune the receiver to receive a broadcast signal +* demodulate the broadcast signal +* demultiplex the analogue video signal and analogue audio + signal. + + .. note:: + + some countries employ a digital audio signal + embedded within the modulated composite analogue signal - + using NICAM signaling.) + +* digitize the analogue video signal and make the resulting datastream + available to the data bus. + +The digital datastream from an Analogue TV card is generated by +circuitry on the card and is often presented uncompressed. For a PAL TV +signal encoded at a resolution of 768x576 24-bit color pixels over 25 +frames per second - a fair amount of data is generated and must be +processed by the PC before it can be displayed on the video monitor +screen. Some Analogue TV cards for PCs have onboard MPEG2 encoders which +permit the raw digital data stream to be presented to the PC in an +encoded and compressed form - similar to the form that is used in +Digital TV. + +The purpose of a simple budget digital TV card (DVB-T,C or S) is to +simply: + +* Tune the received to receive a broadcast signal. * Extract the encoded + digital datastream from the broadcast signal. +* Make the encoded digital datastream (MPEG2) available to the data bus. + +The significant difference between the two is that the tuner on the +analogue TV card spits out an Analogue signal, whereas the tuner on the +digital TV card spits out a compressed encoded digital datastream. As +the signal is already digitised, it is trivial to pass this datastream +to the PC databus with minimal additional processing and then extract +the digital video and audio datastreams passing them to the appropriate +software or hardware for decoding and viewing. + +Getting the card going +~~~~~~~~~~~~~~~~~~~~~~ + +The Device Driver API for DVB under Linux will the following +device nodes via the devfs filesystem: + +* /dev/dvb/adapter0/demux0 +* /dev/dvb/adapter0/dvr0 +* /dev/dvb/adapter0/frontend0 + +The ``/dev/dvb/adapter0/dvr0`` device node is used to read the MPEG2 +Data Stream and the ``/dev/dvb/adapter0/frontend0`` device node is used +to tune the frontend tuner module. The ``/dev/dvb/adapter0/demux0`` is +used to control what programs will be received. + +Depending on the card's feature set, the Device Driver API could also +expose other device nodes: + +* /dev/dvb/adapter0/ca0 +* /dev/dvb/adapter0/audio0 +* /dev/dvb/adapter0/net0 +* /dev/dvb/adapter0/osd0 +* /dev/dvb/adapter0/video0 + +The ``/dev/dvb/adapter0/ca0`` is used to decode encrypted channels. The +other device nodes are found only on devices that use the av7110 +driver, with is now obsoleted, together with the extra API whose such +devices use. + +Receiving a digital TV channel +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +This section attempts to explain how it works and how this affects the +configuration of a Digital TV card. + +On this example, we're considering tuning into DVB-T channels in +Australia, at the Melbourne region. + +The frequencies broadcast by Mount Dandenong transmitters are, +currently: + +Table 1. Transponder Frequencies Mount Dandenong, Vic, Aus. + +=========== =========== +Broadcaster Frequency +=========== =========== +Seven 177.500 Mhz +SBS 184.500 Mhz +Nine 191.625 Mhz +Ten 219.500 Mhz +ABC 226.500 Mhz +Channel 31 557.625 Mhz +=========== =========== + +The digital TV Scan utilities (like dvbv5-scan) have use a set of +compiled-in defaults for various countries and regions. Those are +currently provided as a separate package, called dtv-scan-tables. It's +git tree is located at LinuxTV.org: + + https://git.linuxtv.org/dtv-scan-tables.git/ + +If none of the tables there suit, you can specify a data file on the +command line which contains the transponder frequencies. Here is a +sample file for the above channel transponders, in the old "channel" +format:: + + # Data file for DVB scan program + # + # C Frequency SymbolRate FEC QAM + # S Frequency Polarisation SymbolRate FEC + # T Frequency Bandwidth FEC FEC2 QAM Mode Guard Hier + + T 177500000 7MHz AUTO AUTO QAM64 8k 1/16 NONE + T 184500000 7MHz AUTO AUTO QAM64 8k 1/8 NONE + T 191625000 7MHz AUTO AUTO QAM64 8k 1/16 NONE + T 219500000 7MHz AUTO AUTO QAM64 8k 1/16 NONE + T 226500000 7MHz AUTO AUTO QAM64 8k 1/16 NONE + T 557625000 7MHz AUTO AUTO QPSK 8k 1/16 NONE + +Nowadays, we prefer to use a newer format, with is more verbose and easier +to understand. With the new format, the "Seven" channel transponder's +data is represented by:: + + [Seven] + DELIVERY_SYSTEM = DVBT + FREQUENCY = 177500000 + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = AUTO + CODE_RATE_LP = AUTO + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + INVERSION = AUTO + +For an updated version of the complete table, please see: + + https://git.linuxtv.org/dtv-scan-tables.git/tree/dvb-t/au-Melbourne + +When the Digital TV scanning utility runs, it will output a file +containing the information for all the audio and video programs that +exists into each channel's transponders which the card's frontend can +lock onto. (i.e. any whose signal is strong enough at your antenna). + +Here's the output of the dvbv5 tools from a channel scan took from +Melburne:: + + [ABC HDTV] + SERVICE_ID = 560 + VIDEO_PID = 2307 + AUDIO_PID = 0 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 226500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 3/4 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [ABC TV Melbourne] + SERVICE_ID = 561 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 226500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 3/4 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [ABC TV 2] + SERVICE_ID = 562 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 226500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 3/4 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [ABC TV 3] + SERVICE_ID = 563 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 226500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 3/4 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [ABC TV 4] + SERVICE_ID = 564 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 226500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 3/4 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [ABC DiG Radio] + SERVICE_ID = 566 + VIDEO_PID = 0 + AUDIO_PID = 2311 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 226500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 3/4 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [TEN Digital] + SERVICE_ID = 1585 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 219500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [TEN Digital 1] + SERVICE_ID = 1586 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 219500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [TEN Digital 2] + SERVICE_ID = 1587 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 219500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [TEN Digital 3] + SERVICE_ID = 1588 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 219500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [TEN Digital] + SERVICE_ID = 1589 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 219500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [TEN Digital 4] + SERVICE_ID = 1590 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 219500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [TEN Digital] + SERVICE_ID = 1591 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 219500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [TEN HD] + SERVICE_ID = 1592 + VIDEO_PID = 514 + AUDIO_PID = 0 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 219500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [TEN Digital] + SERVICE_ID = 1593 + VIDEO_PID = 512 + AUDIO_PID = 650 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 219500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [Nine Digital] + SERVICE_ID = 1072 + VIDEO_PID = 513 + AUDIO_PID = 660 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 191625000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [Nine Digital HD] + SERVICE_ID = 1073 + VIDEO_PID = 512 + AUDIO_PID = 0 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 191625000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [Nine Guide] + SERVICE_ID = 1074 + VIDEO_PID = 514 + AUDIO_PID = 670 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 191625000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 3/4 + CODE_RATE_LP = 1/2 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/16 + HIERARCHY = NONE + + [7 Digital] + SERVICE_ID = 1328 + VIDEO_PID = 769 + AUDIO_PID = 770 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 177500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [7 Digital 1] + SERVICE_ID = 1329 + VIDEO_PID = 769 + AUDIO_PID = 770 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 177500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [7 Digital 2] + SERVICE_ID = 1330 + VIDEO_PID = 769 + AUDIO_PID = 770 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 177500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [7 Digital 3] + SERVICE_ID = 1331 + VIDEO_PID = 769 + AUDIO_PID = 770 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 177500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [7 HD Digital] + SERVICE_ID = 1332 + VIDEO_PID = 833 + AUDIO_PID = 834 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 177500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [7 Program Guide] + SERVICE_ID = 1334 + VIDEO_PID = 865 + AUDIO_PID = 866 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 177500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [SBS HD] + SERVICE_ID = 784 + VIDEO_PID = 102 + AUDIO_PID = 103 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 536500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [SBS DIGITAL 1] + SERVICE_ID = 785 + VIDEO_PID = 161 + AUDIO_PID = 81 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 536500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [SBS DIGITAL 2] + SERVICE_ID = 786 + VIDEO_PID = 162 + AUDIO_PID = 83 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 536500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [SBS EPG] + SERVICE_ID = 787 + VIDEO_PID = 163 + AUDIO_PID = 85 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 536500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [SBS RADIO 1] + SERVICE_ID = 798 + VIDEO_PID = 0 + AUDIO_PID = 201 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 536500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE + + [SBS RADIO 2] + SERVICE_ID = 799 + VIDEO_PID = 0 + AUDIO_PID = 202 + DELIVERY_SYSTEM = DVBT + FREQUENCY = 536500000 + INVERSION = OFF + BANDWIDTH_HZ = 7000000 + CODE_RATE_HP = 2/3 + CODE_RATE_LP = 2/3 + MODULATION = QAM/64 + TRANSMISSION_MODE = 8K + GUARD_INTERVAL = 1/8 + HIERARCHY = NONE |