[mythtv] Documentation of DVB DB parameters

Ben Bucksch linux.news at bucksch.org
Thu May 1 03:42:11 EDT 2003

To be able to try out the DVB code, you need to fill your DB manually 
with the configuration of your card and channels. Somebody write a 
script/program to import a channels.conf? Anyways, here is the 
documentation for it. I'll submit it for inclusion in CVS somewhere 
(like keys.txt), but I may improve it before that. This email is 
available in HTML and plaintext.

  1. Purpose

This doc tries to describe Myth's database. For now, it is spotty.

  2. Format of this document

Top-level headings (level 1) are table names (apart from the general 
description. Headings of level 2 are column names. The body usually 
starts with the data type. Integer means a round number.

  3. Property Lists

These are several name/value pairs in a single column, to keep the DB 
layout simpler.
The headings of level 3 define in which cases the properties apply (e.g. 
a property makes only sense for DVB-S).
The headings of level 4 (e.g. "freq") define the name of the property, 
including spaces, capitalization is ignored.
Values are technically strings, but the implementation will usually 
complain and ignore the value, if they are not in the expected 
format/data type. The expected format is noted directly following the 
heading. Boolean (or in short bool) means "1" for yes/on and "0" for 
no/false. For strings, capitalization may or may not matter, depending 
on the property, spaces usually do matter.

Currently, property lists are stored in columns directly in the table, 
in the format "name1=value1|name2=value2", e.g. 
"freq=3563457|pol=v|symbol rate=22000".


  4. channel

  4.1. channum

String. Used to be the phyiscal (on-the-air) channel, the sometimes 
internal id for channels and also the way users change the channel. The 
first usage is now moved to the tuning column.

  4.2. tuning

Property list. Parameters needed to change the channel on a given card.

Typically, if one of these properties differs between 2 channels, these 
2 channels cannot be tuned to at the same time using the same card.

  4.2.1. Analog TV channum

String (usually integer) The phyiscal (on-the-air) channel, in a 
country-specific canonical format, e.g. "11" or "SE05". finetune

Integer. To slighly tune a bit higher/lower than the channum, to get a 
better receivement of the channel.

  4.2.2. DVB all freq

Integer. Frequency, in Hz (?)

  4.2.3. DVB-S pol

"H" or "V". Polarization - horiozontal or vertical symbol rate

Integer tone

Bool. No idea what this is. diseqc

Integer. Controls motorized rotating sat dishes, you only need this, if 
you have such a dish with a motor. You'll know, if you do.

  4.2.4. DVB-C inversion

bool or "auto" bandwidth

6, 7, 8 or "auto"
in MHz. hp code rate

"1_2", "2_3", "3_4", "4_5", "5_6", "6_7", "7_8", "8_9" or "auto"
FEC_1_2, FEC_2_3 and so on. lp code rate

Format same as hp code rate. Only needed, if hierarchy is not none. 
Noone needs this yet, to my knowledge. modulation

"QPSK", "QAM_16", "QAM_32", "QAM_64", "QAM_128", "QAM_256" or "auto" transmission mode

2, 8 or "auto"
in K. guard interval

4, 8, 16, 32 or "auto"
in 1/n (?) hierarchy

"none" = 0, 1, 2, 4 or "auto"
Noone needs this yet, to my knowledge.

  4.3. subtuning

Property list.
Parameters needed to change the channel, but usually on the software level.
For DVB, if these properties differ between 2 channels, but all 
properties in column "tuning" match, these 2 channels may still be 
receiveable at the same time using the same card.
For other runing types, the meaning/usage is to be defined.

  4.3.1. DVB pid vid

Integer. Program ID for the video stream pid aud

Integer. Program ID for the audio stream

  5. capturecard

  5.1. cardtype

"V4L", "MPEG, "DVB" or "Stream"
V4L: Analog TV cards without hardware encoding
MPEG: Analog TV cards with hardware encoding
DVB: DVB cards (getting MPEG directly from the feed). Experimental.
Stream: Getting MPEG (MPEG PS, ideally) from an external program via 
stdout (pipe). Untested.

  5.2. options

  5.2.1. DVB use ts

Bool. Get a full transport stream from the hardware/driver and filter 
out the channel within MythTV.
Not sure yet what is best for each card type (full card or budget card), 
depends on driver, userspace library, computing power etc., needs testing. dvb type

"S", "C" or "T"
DVB-S (satellite), DVB-C (cable) or DVB-T (terrestrical = antenna)
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