Kamaelia.Support.DVB.Descriptors

• Support functions for parsing DVB data structures
  • Example Usage
  • Parsing Descriptors
  • How does it Work?
  • References
    • Mappings, Tables, Values
  • Service types
  • Stream Component Mappings
  • Private Data Specifiers
  • Content Types

Support functions for parsing DVB data structures

A collection of functions for parsing 'descriptor' elements of information tables in DVB data streams. Descriptors contain data such as channel names, tuning information for other multiplexes, and information about the audio/video streams making up a channel.

Example Usage

A simple loop to parse a set of descriptors stored consecutively in a string:

i=0
while i < len(setOfDescriptors):
    parsed, i = parseDescriptor(i, setOfDescriptors)
    (tag, data) = parsed
    print "Descriptor found with tag",tag
    for (key,value) in data.items():
        print key, "=", value

Parsing Descriptors

Call the parseDescriptor() function, passing it the string containing the descriptor and the index of the beginning of the descriptor within the string.

parseDescriptor() will return the parsed descriptor:

(tag, data)
    - tag = the ID of this descriptor type
    - data = dictionary containing the parsed descriptor data:
        { type : WhatKindOfDescriptor,
          key  : value,
          key2 : value2,
          ...
        }

All parsed descriptor data will contain the 'type' key. The remaining key,value pairs are specific to the type of descriptor.

parseDescriptor() uses helper functions to parse each particular descriptor. See their documentation to see what descriptors are currently supported and what data to expect in the dictionary.

How does it Work?

parseDescriptor() uses helper functions to parse each particular descriptor. parseDescriptor() extracts the 'tag' defining the descriptor type, and the length of the descriptor. A mapping table maps from tags to parser functions.

Each parser function is of the form::

parse(data,i,length,end) -> dict(parsed descriptor elements)

'data' is a string containing the descriptor. 'i' is the index into the string of the start of the descriptor. 'length' is the length of the descriptor payload and end' is the index of the first point after the descriptor.

References

For the full description of the descriptors available see the following MPEG and DVB standards documents:

• ISO/IEC 13818-1 (aka "MPEG: Systems") "GENERIC CODING OF MOVING PICTURES AND ASSOCIATED AUDIO: SYSTEMS" ISO / Motion Picture Experts Grou7p
• ETSI EN 300 468 "Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems" ETSI / EBU (DVB group)
• "Digital Terrestrial Television: Requirements for Interoperability" Issue 4.0+ (aka "The D book") UK Digital Television Group
• ETSI TS 102 323 Technical Specification: "Digital Video Broadcasting (DVB); Carriage and signalling of TV-Anytime information in DVB transport streams" ETSI / EBU (DVB group)

Mappings, Tables, Values

Various mappings, tables, values etc. used by the DVB standard.

Service types

Types of services (channel) that can be found in a DVB multiplex:

"digital television service",
"digital radio sound service",
"Teletext service",
"NVOD reference service",
"NVOD time-shifted service",
"mosaic service",
"PAL coded signal",
"SECAM coded signal",
"D/D2-MAC",
"FM Radio",
"NTSC coded signal",
"data broadcast service",
"RCS Map",
"RCS FLS",
"DVB MHP service",
"MPEG-2 HD digital television service",
"advanced codec SD digital television service",
"advanced codec SD NVOD time-shifted service",
"advanced codec SD NVOD reference service",
"advanced codec HD digital television service",
"advanced codec HD NVOD time-shifted service",
"advanced codec HD NVOD reference service",

Stream Component Mappings

Mappings from (stream_component, component_type) values to their actual meanings. Used in 'component' descriptors:

(0x01, 0x01) : ("video",                 "4:3 aspect ratio, 25 Hz"),
(0x01, 0x02) : ("video",                 "16:9 aspect ratio with pan vectors, 25 Hz"),
(0x01, 0x03) : ("video",                 "16:9 aspect ratio without pan vectors, 25 Hz"),
(0x01, 0x04) : ("video",                 "> 16:9 aspect ratio, 25 Hz"),
(0x01, 0x05) : ("video",                 "4:3 aspect ratio, 30 Hz"),
(0x01, 0x06) : ("video",                 "16:9 aspect ratio with pan vectors, 30 Hz"),
(0x01, 0x07) : ("video",                 "16:9 aspect ratio without pan vectors, 30 Hz"),
(0x01, 0x05) : ("video",                 "> 16:9 aspect ratio, 30 Hz"),
(0x01, 0x09) : ("high definition video", "4:3 aspect ratio, 25 Hz"),
(0x01, 0x0A) : ("high definition video", "16:9 aspect ratio with pan vectors, 25 Hz"),
(0x01, 0x0B) : ("high definition video", "16:9 aspect ratio without pan vectors, 25 Hz"),
(0x01, 0x0C) : ("high definition video", "> 16:9 aspect ratio, 25 Hz"),
(0x01, 0x0D) : ("high definition video", "4:3 aspect ratio, 30 Hz"),
(0x01, 0x0E) : ("high definition video", "16:9 aspect ratio with pan vectors, 30 Hz"),
(0x01, 0x0F) : ("high definition video", "16:9 aspect ratio without pan vec., 30 Hz"),
(0x01, 0x10) : ("high definition video", "> 16:9 aspect ratio, 30 Hz"),
(0x02, 0x01) : ("audio",                 "single mono channel"),
(0x02, 0x02) : ("audio",                 "dual mono channel"),
(0x02, 0x03) : ("audio",                 "stereo (2 channel)"),
(0x02, 0x04) : ("audio",                 "multi-lingual, multi-channel"),
(0x02, 0x05) : ("audio",                 "surround sound"),
(0x02, 0x40) : ("audio description for the visually impaired", ""),
(0x02, 0x41) : ("audio for the hard of hearing",               ""),
(0x03, 0x01) : ("EBU Teletext subtitles",  ""),
(0x03, 0x02) : ("associated EBU Teletext", ""),
(0x03, 0x03) : ("VBI data",                ""),
(0x03, 0x10) : ("DVB subtitles (normal)", "with no monitor aspect ratio criticality"),
(0x03, 0x11) : ("DVB subtitles (normal)", "for display on 4:3 aspect ratio monitor"),

Private Data Specifiers

Specifiers defining various types of private data payload:

0x00000001 : "SES",
0x00000002 : "BSkyB 1",
0x00000003 : "BSkyB 2",
0x00000004 : "BSkyB 3",
0x000000BE : "BetaTechnik",
0x00006000 : "News Datacom",
0x00006001 : "NDC 1",
0x00006002 : "NDC 2",
0x00006003 : "NDC 3",
0x00006004 : "NDC 4",
0x00006005 : "NDC 5",
0x00006006 : "NDC 6",
0x00362275 : "Irdeto",
0x004E544C : "NTL",
0x00532D41 : "Scientific Atlanta",
0x44414E59 : "News Datacom (IL) 1",
0x46524549 : "News Datacom (IL) 1",
0x53415053 : "Scientific Atlanta",

Content Types

Level 1 content types/genres:

0x1 : "Movie/Drama",
0x2 : "News/Current Affairs",
0x3 : "Show/Game show",
0x4 : "Sports",
0x5 : "Children's/Youth",
0x6 : "Music/Ballet/Dance",
0x7 : "Arts/Culture (without music)",
0x8 : "Social/Political issues/Economics",
0x9 : "Childrens/Youth Education/Science/Factual",
0xa : "Leisure hobbies",
0xb : "Misc",
0xf : "Drama", # user defined (specified in the UK "D book")

Note that 0xf is a user defined field. The mapping it is assigned here is that used in the UK "D book" specification.

Level 2 content types/genres:

# movie/drama
0x10 : "General",
0x11 : "Detective/Thriller",
0x12 : "Adventure/Western/War",
0x13 : "Science Fiction/Fantasy/Horror",
0x14 : "Comedy",
0x15 : "Soap/Melodrama/Folkloric",
0x16 : "Romance",
0x17 : "Serious/ClassicalReligion/Historical",
0x18 : "Adult Movie/Drama",

# news/current affairs
0x20 : "General",
0x21 : "News/Weather Report",
0x22 : "Magazine",
0x23 : "Documentary",
0x24 : "Discussion/Interview/Debate",

# show/game show
0x30 : "General",
0x31 : "Game show/Quiz/Contest",
0x32 : "Variety",
0x33 : "Talk",

# sports
0x40 : "General",
0x41 : "Special Event (Olympics/World cup/...)",
0x42 : "Magazine",
0x43 : "Football/Soccer",
0x44 : "Tennis/Squash",
0x45 : "Team sports (excluding football)",
0x46 : "Athletics",
0x47 : "Motor Sport",
0x48 : "Water Sport",
0x49 : "Winter Sports",
0x4a : "Equestrian",
0x4b : "Martial sports",

# childrens/youth
0x50 : "General",
0x51 : "Pre-school",
0x52 : "Entertainment (6 to 14 year-olds)",
0x53 : "Entertainment (10 to 16 year-olds)",
0x54 : "Informational/Educational/Schools",
0x55 : "Cartoons/Puppets",

# music/ballet/dance
0x60 : "General",
0x61 : "Rock/Pop",
0x62 : "Serious music/Classical Music",
0x63 : "Folk/Traditional music",
0x64 : "Jazz",
0x65 : "Musical/Opera",
0x66 : "Ballet",

# arts/culture
0x70 : "General",
0x71 : "Performing Arts",
0x72 : "Fine Arts",
0x73 : "Religion",
0x74 : "Popular Culture/Tradital Arts",
0x75 : "Literature",
0x76 : "Film/Cinema",
0x77 : "Experimental Film/Video",
0x78 : "Broadcasting/Press",
0x79 : "New Media",
0x7a : "Magazine",
0x7b : "Fashion",

# social/political/economic
0x80 : "General",
0x81 : "Magazine/Report/Domentary",
0x82 : "Economics/Social Advisory",
0x83 : "Remarkable People",

# children's youth: educational/science/factual
0x90 : "General",
0x91 : "Nature/Animals/Environment",
0x92 : "Technology/Natural sciences",
0x93 : "Medicine/Physiology/Psychology",
0x94 : "Foreign Countries/Expeditions",
0x95 : "Social/Spiritual Sciences",
0x96 : "Further Education",
0x97 : "Languages",

# leisure hobbies
0xa0 : "General",
0xa1 : "Tourism/Travel",
0xa2 : "Handicraft",
0xa3 : "Motoring",
0xa4 : "Fitness & Health",
0xa5 : "Cooking",
0xa6 : "Advertisement/Shopping",
0xa7 : "Gardening",

# misc
0xb0 : "Original Language",
0xb1 : "Black and White",
0xb2 : "Unpublished",
0xb3 : "Live Broadcast",

# drama (user defined, specced in the UK "D-Book")
0xf0 : "General",
0xf1 : "Detective/Thriller",
0xf2 : "Adventure/Western/War",
0xf3 : "Science Fiction/Fantasy/Horror",
0xf4 : "Comedy",
0xf5 : "Soap/Melodrama/Folkloric",
0xf6 : "Romance",
0xf7 : "Serious/ClassicalReligion/Historical",
0xf8 : "Adult",

Note that 0xf0 to 0xff range is a user defined field. The mapping it is assigned here is that used in the UK "D book" specification.

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