Difference between revisions of "HERAD"
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| <tt>UINT16</tt> || <tt>wSpeed</tt> || Ticks per second (tick = roughly 0.00187 seconds; need more research for exact value) | | <tt>UINT16</tt> || <tt>wSpeed</tt> || Ticks per second (tick = roughly 0.00187 seconds; need more research for exact value) | ||
|- | |- | ||
| − | | <tt>UINT8[32]</tt> || <tt>bUnknown5</tt> || Array of bytes (unknown) seems to be only in '''AGD''' files | + | | <tt>UINT8[32]</tt> || <tt>bUnknown5</tt> || Array of bytes (unknown) seems to be only in '''AGD''' files (most likely panning values for Adlib Gold songs) |
|- | |- | ||
| <tt>DATA[]</tt> || <tt>data</tt> || MIDI tracks (each track ends with 0xFF) | | <tt>DATA[]</tt> || <tt>data</tt> || MIDI tracks (each track ends with 0xFF) | ||
Revision as of 01:24, 4 April 2016
| HERAD System | |||||
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| Developer: | Rémi Herbulot | ||||
| Header: | Custom | ||||
| Content: | Notational | ||||
| Instruments: | Optional | ||||
Target Output
| |||||
| Released: | 1992-??-?? | ||||
| First Game: | ? | ||||
| Extensions |
|
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Herbulot AdLib (HERAD) System was created by Rémi Herbulot, one of Cryo Interactive Entertainment co-founders and lead programmers. Stéphane Picq, Cryo's first music composer also helped design HERAD with Herbulot. There are two versions of HERAD that are known to exist.
Contents
Players
- RdosPlay - DOS - only version 1 (OPL2/OPL3 music)
Converters
HERAD to ?
? to HERAD
Games
| Released | Title | Sample |
|---|---|---|
| 1992-??-?? | Dune (DOS) | |
| 1992-??-?? | KGB (DOS) | |
| 1993-??-?? | MegaRace (DOS) |
Technical
- File extensions stands for different sound devices:
- ADL, SDB - AdLib/Sound Blaster (OPL2)
- AGD - AdLib Gold (OPL3)
- M32 - Roland MT-32 (LA32)
- HSQ are compressed files with Herbulot Sequencer algorithm.
- The internal music notation is similar to MIDI, except Pitch Bend and Meta events.
- M32 files usually contain one multi-channel track, while ADL/AGD files may contain multiple tracks.
File structure
All values seems to be in little endian format. The structure identification is incomplete.
| Data type | Name | Description |
|---|---|---|
| UINT16 | wFileSize | Size of uncompressed file (different between versions) |
| UINT16[21] | wOffsets | Array of relative offsets to the MIDI tracks (0 = track doesn't exist) |
| UINT16 | wLoopStart | Loop starts at this measure (0 = don't loop) |
| UINT16 | wLoopEnd | Loop ends at this measure (0 = don't loop) |
| UINT16 | wLoopCount | Number of times the selected measures will play (0 = loop forever; >0 - play N times) |
| UINT16 | wSpeed | Ticks per second (tick = roughly 0.00187 seconds; need more research for exact value) |
| UINT8[32] | bUnknown5 | Array of bytes (unknown) seems to be only in AGD files (most likely panning values for Adlib Gold songs) |
| DATA[] | data | MIDI tracks (each track ends with 0xFF) |
| DATA[] | instruments | AdLib/Soundblaster instruments (doesn't present in M32) |
Version Compatibility
The format has two versions at least, which have major differences. However neither version has any FourCC or data denoting which version it is, so each music file needs to be inspected to detect the proper format version.
The first version was used in Dune (DOS) and KGB (DOS), and the second version was used in MegaRace (DOS). There are different ways you can loop a song; you can either loop a short segment or loop the song indefinitely. Both require specifying the start and end points. In Dune, in order for music to loop, this data must be in place, but for music playback in MegaRace, the songs will automatically repeat forever even if the wLoopCount field specifies if the song should only be played once. Because the music will automatically loop, several tracks in MegaRace (NewSan, Maeva and Terminal City) have short measure loops that are played back but the music continues to loop the song from beginning to end. The other remaining tracks from MegaRace (Factory Land, Skyholder and Fractalian Space) have intros to them that are not repeated so their loop points start at the end of the intro and finish when the song is over.
For the 1st version wFileSize value represents total file size, for the 2nd version it represents file size without instruments data block. Also there are differences in MIDI notation, which described below.
MIDI notation
- The most of status bytes are compatible with MIDI standard.
- It looks like that running status is not supported as all known songs programmed in HERAD never use it.
| MIDI message | Description | MIDI compatible |
|---|---|---|
| 8# xx xx | Note Off (version 1) | Yes |
| 8# xx | Note Off (version 2) | No |
| 9# xx xx | Note On | Yes |
| A# ?? ?? | Poly Aftertouch (unused) | Unknown |
| B# ?? ?? | Control Change (unused) | Unknown |
| C# xx | Program Change (uses internal instruments for AGD and SDB) | Yes |
| D# xx | Channel Aftertouch | Yes |
| E# xx | Pitch Bend | No |
| FF | Track End |
For the Note Off command in version 2 songs, the velocity byte has been removed. The Pitch Bend command has only the MSB byte available. Like the MIDI Standard dictates, 0x40 is the "center" of the pitch bend range. Sending this data byte after the Pitch Bend status byte will result in no change to the pitch. Anything higher than 0x40, the pitch will go up, whereas any value less than 0x40 produces a lower pitch. In the MegaRace music files, Channel Aftertouch only occurs one time in one song (Fractalian Space).
Instrument Data
The instrument chunk contains all the OPL register values needed for each instrument, along with some macros that control various parameters of the instrument during playback. Each instrument is 0x28 bytes long.
It seems that the OPL register values are almost in the exact same layout as the BNK format (technical). Thanks to Malvineous for his documentation on the BNK file format.
These offsets are still a work in progress and need more research.
| Offset | Size | Name | Description | OPL base register | Value range |
|---|---|---|---|---|---|
| 0x0 | 1 | |
Possibly an identifier (0x0 in version 1 songs, 0x1 or 0xFF in version 2 songs) | ||
| 0x1 | 1 | |
Possibly an identifier | ||
| 0x2 | 1 | ksl | |
0x40 (bits 6-7) | |
| 0x3 | 1 | multiple | |
0x20 (bits 0-3) | |
| 0x4 | 1 | feedback | |
0xC0 (bits 1-3) | |
| 0x5 | 1 | attack | |
0x60 (upper four bits) | |
| 0x6 | 1 | sustain | |
0x80 (upper four bits) | |
| 0x7 | 1 | eg | |
0x20 (bit 5) | nonzero value is on |
| 0x8 | 1 | decay | |
0x60 (lower four bits) | |
| 0x9 | 1 | releaseRate | |
0x80 (lower four bits) | |
| 0xA | 1 | totalLevel | |
0x40 (bit 0-5) | uses all bits; output level can still be modified by output level byte 0x1E |
| 0xB | 1 | am | 0x20 (bit 7) | ||
| 0xC | 1 | vib | 0x20 (bit 6) | ||
| 0xD | 1 | ksr | |
0x20 (bit 4) | |
| 0xE | 1 | con | |
0xC0 (bit 0, inverted) | 0: OPL bit set to 1 other: OPL bit set to 0 |
| 0xF | 1 | ksl | |
0x40 (bits 6-7) | |
| 0x10 | 1 | multiple | |
0x20 (bits 0-3) | |
| 0x11 | 1 | feedback | |
0xC0 (bits 1-3) | This byte seems to have garbage data in it and is not used |
| 0x12 | 1 | attack | |
0x60 (upper four bits) | |
| 0x13 | 1 | sustain | |
0x80 (upper four bits) | |
| 0x14 | 1 | eg | |
0x20 (bit 5) | nonzero value is on |
| 0x15 | 1 | decay | |
0x60 (lower four bits) | |
| 0x16 | 1 | releaseRate | |
0x80 (lower four bits) | |
| 0x17 | 1 | totalLevel | |
0x40 (bit 0-5) | uses all bits; output level can still be modified by output level byte 0x1F |
| 0x18 | 1 | am | 0x20 (bit 7) | ||
| 0x19 | 1 | vib | 0x20 (bit 6) | ||
| 0x1A | 1 | ksr | |
0x20 (bit 4) | |
| 0x1B | 1 | con | |
0xC0 (bit 0, inverted) | So far, this seems to be always set at zero. |
| 0x1C | 1 | |
0xE0 (bits 0-1) | ||
| 0x1D | 1 | |
0xE0 (bits 0-1) | ||
| 0x1E | 1 | |
Uses the MIDI NoteOn velocity to control the Modulator Output level (goes from 0 to 4; 0 = no velocity change, 4 = softest velocity change) | ||
| 0x1F | 1 | |
Same as previous macro, only this affects the Carrier operator. Seems to multiply the velocity value; as a result some notes that are too loud or quiet will not be affected since the sum will be out of range for the OPL chip. | ||
| 0x20 | 1 | |
0xC0 (bits 1-3) | This byte seems to be a duplicate control for Feedback, need to do more research. | |
| 0x21 | 1 | |
Increases pitch bend range (Fine tune = 0, Coarse tune = 1) | ||
| 0x22 | 1 | |
Normally set at 0x0, 0xC = an octave higher | ||
| 0x23 | 1 | Duration of the pitch bend in ticks | |||
| 0x24 | 1 | |
Setting to 0x18, while the coarse flag is enabled produces semi-tone intervals, however they start to go out of tune after several notes. | ||
| 0x25 | 1 | |
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| 0x26 | 1 | |
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| 0x27 | 1 | |
Links
- File:MegaRace - DOS - Credits.png - HERAD system is mentioned in the credits of MegaRace (DOS).
- mobygames.com/developer/sheet/view/developerId,1760/ - HERAD System mentioned on MobyGames.
- sourceforge.net/p/adplug/feature-requests/18/ - Format support request on AdPlug repository.
