Difference between revisions of "HERAD"
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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 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)]]. | + | 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 <tt>wLoopCount</tt> 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 <tt>wFileSize</tt> 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. | For the 1st version <tt>wFileSize</tt> 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. |
Revision as of 23:56, 27 March 2016
HERAD System | |||||
Developer: | Rémi Herbulot | ||||
Header: | Custom | ||||
Content: | Notational | ||||
Instruments: | Optional | ||||
Target Output
| |||||
Released: | 1992-??-?? | ||||
First Game: | ? | ||||
Extensions |
|
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 |
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's unknown whether running status mode is supported, since the most music files doesn't 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 |
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 | |
|||
0x1 | 1 | |
|||
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. |
0x1E | 1 | Seems to follow the note velocity (0 = loudest, F = softest) | |||
0x1F | 1 | |
Seems to follow the note velocity (0 = loudest, F = softest) | ||
0x20 | 1 | |
Seems to increases Feedback depending on note velocity | ||
0x21 | 1 | |
Increases pitch bend range (seems like it's a flag: 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 | |
Pitch bend range | ||
0x25 | 1 | |
|||
0x26 | 1 | |
|||
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.