MHEG Activities
(The 'Baseline' Profile)
This page carries information of use to MHEG engine developers and application authors.
Text Metrics
In the Digital Terrestrial Television MHEG-5 Specification (D-Book 6.1) chapter 15 specifies the use of the metrics contained within the Tiresias font v7.51. Unfortunately, it would appear that more than one version of "Tiresias v7.51" has been produced by Bitstream. Some of these versions may have differing values for the font bounds defined in that chapter. For optimum conformance with the MHEG-5 Test Suite it is recommended that MHEG-5 engines use the following values (in outline resolution):
- xMin = -40
- yMin = -62
- xMax = 271
- yMax = 231
Known MHEG engine event, content hook, input event and input register values, MHEG character set values and font names
Several working groups within the DTG and elsewhere are developing extensions to the UK MHEG Profile and, to facilitate this, a registry of all MHEG engine event, content hook, input event and input register values, together with MHEG character set values and font names, that have ever been defined is included here in order to ensure that values are not re-used.
We are grateful to Chris Poole, BBC, for the following information.
Engine Events
<0 - manufacturer specific
0 - reserved
1 - QuitApp (1.05, obsolete)
2 - GroupIDRefError (1.06)
3 - ContentRefError (1.06)
4 - TextKeyFunction (1.06)
5 - reserved (1.06)
6 - VideoPrefChanged (1.06)
7 - PauseResume (1.06)
8 - SubtitlePrefChanged (1.05, obsolete)
9 - NetworkBootInfo (1.06)
10 - NonDestructiveTuneOK (UK Freesat)
16 - CancelKeyFunction (1.06)
20 - PVRChangedEvent (NZ Freeview)
100 - RedKeyFunction (1.06)
101 - GreenKeyFunction (1.06)
102 - YellowKeyFunction (1.06)
103 - BlueKeyFunction (1.06)
200 - ICStatusChanged (DTG ICWG)
201 - ICLocalError (DTG ICWG)
202 - ICNetworkError (DTG ICWG)
203 - ICRemoteError (DTG ICWG)
204 - ICSecurity (DTG ICWG)
300 - reserved by S&T
Content Hooks
Font class
1 - DAVIC outline font (DAVIC, obsolete)
10 - OpenType font (UK Freesat)
Palette class
1 - CLUT definition segment (DAVIC, obsolete)
Bitmap class
1 - reserved (DAVIC, obsolete)
2 - MPEG-2 I-frame for video plane (1.06)
3 - region definition segment (DAVIC, obsolete)
4 - PNG image (1.06)
5 - MPEG-2 I-frame for image plane (UK Freesat)
6 - JPEG image (DTG HD MHEG)
7 - H.264/AVC I-frame for video plane (DTG HD MHEG)
8 - H.264/AVC I-frame for image plane (UK Freesat)
10 - MPEG-2 I-frame to be displayed in Aligned Mode (1.05, obsolete)
Text class
1 - HTML 3.2 subset (DAVIC, obsolete)
10 - UTF-8 encoded text with UK Profile markup (1.06)
11 - UTF-16 encoded text with UK Profile markup (non-European profiles)
EntryField class
1 - unicode or latin-1 (DAVIC, obsolete)
10 - UTF-8 subset (1.06)
11 - UTF-16 encoded text with UK Profile markup (non-European profiles)
Hypertext class
1 - HTML 3.2 subset (DAVIC, obsolete)
10 - UTF-8 encoded text with UK Profile markup (1.06)
11 - UTF-16 encoded text with UK Profile markup (non-European profiles)
Stream class
1 - (DAVIC, obsolete)
2 - (DAVIC, obsolete)
3 - (DAVIC, obsolete)
4 - (DAVIC, obsolete)
5 - (DAVIC, obsolete)
6 - (DAVIC, obsolete)
7 - (DAVIC, obsolete)
10 - Broadcast MPEG program conforming to the UK D-book (1.06)
11 - MPEG-1 layer II audio elementary stream (1.06)
12 - Broadcast MPEG program to be displayed in Tuner Mode (1.05, obsolete)
13 - HE-AAC audio stream (DTG HD MHEG)
14 - AC-3 or E-AC-3 audio stream (DTG HD MHEG)
LineArt class
None known
CursorShape class
None known
InterchangedProgram class
1 - Java (MHEG-6 / DAVIC, obsolete)
User input events
1 - Up (1.06)
2 - Down (1.06)
3 - Left (1.06)
4 - Right (1.06)
5 - '0' (1.06)
6 - '1' (1.06)
7 - '2' (1.06)
8 - '3' (1.06)
9 - '4' (1.06)
10 - '5' (1.06)
11 - '6' (1.06)
12 - '7' (1.06)
13 - '8' (1.06)
14 - '9' (1.06)
15 - OK/select (1.06)
16 - Back/cancel/exit (1.06)
17 - Help (DAVIC, obsolete)
18-99 - reserved (DAVIC, obsolete)
100 - Red (1.06)
101 - Green (1.06)
102 - Yellow (1.06)
103 - Blue (1.06)
104 - Text (1.06)
105 - Info (UK Freesat)
120 - DVR stop (UK Freesat)
121 - DVR play (UK Freesat)
122 - DVR pause (UK Freesat)
300 - reserved by S&T
Input event registers
1 - arrows, numbers, select, exit, help (DAVIC, obsolete)
2 - arrows, select, exit, help (DAVIC, obsolete)
3 - colours, text, back (1.06)
4 - arrows, colours, numbers, text, OK, back (1.06)
5 - arrows, colours, text, OK, back (1.06)
6 - arrows, colours, numbers, DVRs, info, text, OK, back (UK Freesat)
13 - reserved by S&T
14 - reserved by S&T
15 - reserved by S&T
Character set values
1 - Latin1 (DAVIC, obsolete)
2 - Unicode (DAVIC, obsolete)
10 - UK Profile Unicode subset encoded with UTF-8 (1.06)
11 - reserved by S&T
12 - reserved by S&T
13 - reserved by S&T
Font names
rec://font/uk1 - Tiresias 7.51 (1.06)
Updated February 2009