Mockbird
Interface Libarary and Synthesizer Setup Tool for Mockingbird-OTTO
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Public Member Functions | Static Public Member Functions | Public Attributes | Static Public Attributes | List of all members
Soundscape::InstrumentLayer Struct Reference

One layer of a melodic instrument. More...

#include <layer.h>

Public Member Functions

char * format (char *target)
 formats the specification as string.
 

Static Public Member Functions

static InstrumentLayer parse (const char *input)
 parse a layer specification according to the specication given in the class comment.
 

Public Attributes

std::uint16_t patch: 10
 number of the patch to play
 
std::int16_t base_pan: 6
 fixed offset of panning adjustment (raw scale: -32 to +31)
 
std::int16_t pitch
 pitch adjustment in 2048th of an octave
 
std::uint8_t volume: 7
 attenuation of 63.5dB (0) to 0dB (127) given in steps of 0.5dB
 
std::uint8_t exists: 1
 set if this layer is present
 
std::uint8_t pan_mode: 3
 parameter used for linear panning adjustment
 
std::int8_t pan_scale: 5
 scale for linear panning adjustment.
 
std::uint8_t min_val: 7
 minimum (inclusive) of limited key or velocity range, 0 if no limit
 
std::uint8_t dispatch_on_velocity: 1
 if set, limit on velocity, if clear, limit on key
 
std::uint8_t max_val: 7
 maximim (inclusive) of limited key or velocity range, 127 if no limit
 
std::uint8_t boost6db: 1
 add a fixed 6dB boost to the patch if set.
 

Static Public Attributes

static const std::size_t maxlen = 60
 maximum length of patch description returned by format.
 
static const std::uint8_t endian_remap []
 order of bytes to be sent or received from the big-endian firmware.
 
static const char *const pan_keyword []
 keywords for the 8 possible linear panning parameters
 

Detailed Description

One layer of a melodic instrument.

This structure describes the binary format of the description of one layer of an melodic instrument. A melodic instrument consists of up to four layers, each of which can be limited to a certain velocity or key range (but not both).

Each layer describes a single patch to be played. Most synthesizer parameters are specified on the patch level, the layer specification adds extra modifiers, though. Furthermore, patches are monophonic, so panning/stereo definition is fully specified at the layer layer.

This class also implements a textual representation of the layer definition. The syntax is quite strict, case sensitive (although it needs to be completely lowercase, so a frontend might lowercase its input to provide case-insignificance).

The layer syntax consists of these elements:

  1. An optional condition specification, bracketed in [ and ]. The opening bracket is followed the keyword vel or key is expected, without a space inbetween. After the keyword, one or more spaces are required before a number, which indicates the minimum key or velocity this layer applies to. If the ] follows directly, the layer applies only to a single key or velocity, otherwise, a - and the maximum key or velocity is required before the closing bracket (no spaces). If this optional specification is missing, this layer applies for any note.
  2. The patch number, followed by at least one space.
  3. The volume specification. It specifies an attenuation of the patch by 0dB to 63.5dB at a resolution of 0.5dB. As this is an attenuation, the specification is a negative number or zero, with the fractional part missing, being .5 or being .0. This number may be followed by an optional boost specification spelled +6 which sets a control bit that the patch is to be played 6dB louder. the volume specification ends in db (no capital B). There are no space characters in the entire volume specification.
  4. An optional tuning adjustment. It consists of the keyword tune followed by a number, optionally followed by an unit. A negative adjustment lowers the pitch, while a positive adjustment raises the pitch. The allowed units are oct for octaves, st for semitones or ct for cents (percent of a semitone). All of these scales specify a frequency multiplier, just as the raw scale does. The raw scale (no unit specified) is given in 2048th of an octave. So all these adjustments play the sample one octave above the indicated pitch: 1oct, 12st, 1200ct or 2048. If the tuning adjustment is missing, an adjustment of zero is used.

  5. An optional panning specification. The base panning is set by the MIDI panning control on the respective channel, and this panning is added to it. As with MIDI, the panning is given as 7-bit number. The adjustment is specified as a signed number between -64 and +63 with 0 being "center". The resulting panning is clamped to that range as well. The panning specification consists of an offset optionally followed by a linear adjustment. If a linear adjustment is present, it is introduced with + or - after the offset, followed by a scale factor, which then must be followed by * and one of these 8 keywords:

    • lfo1 - the output of the first LFO (-1..1)
    • lfo2 - the output of the second LFO (-1..1)
    • env1 - the output of the first envelope generator (0..1)
    • ukey - the key (unsigned), on a scale of 0..1
    • skey - the key (signed), on a scale of -1..1
    • vel - the velocity, on a scale of 0..1
    • rnd - a random value assigned at NOTE ON time
    • mod - the MIDI modulation wheel (-1..1)

    Note that -1 actually means -1, while +1 is +127/128. In the case of skey, -1 is -127/128. As the modulation wheel only has 7 bit resolution, its range is -1 .. +63/64.

A layer that has its exist bit clear is represented by the plain keyword skip

This structure is a plain old data object, that is (except for endianess) identical to the byte pattern used by the firmware.

Member Function Documentation

◆ format()

char * Soundscape::InstrumentLayer::format ( char * target)

formats the specification as string.

Parameters
targetthe buffer, which should be of size maxlen.
Returns
the buffer given by target.

◆ parse()

static InstrumentLayer Soundscape::InstrumentLayer::parse ( const char * input)
static

parse a layer specification according to the specication given in the class comment.

Parameters
inputC string containing the textual representation
Returns
Instrument layer
Exceptions
`std::runtime_error`or a derived class on invalid inputs.

Member Data Documentation

◆ endian_remap

const std::uint8_t Soundscape::InstrumentLayer::endian_remap[]
static

order of bytes to be sent or received from the big-endian firmware.

As the first two of the 8 bytes are 16-bit quantities, those need to be swapped, so this constant is

{1, 0, 3, 2, 4, 5, 6, 7}

◆ pan_scale

std::int8_t Soundscape::InstrumentLayer::pan_scale

scale for linear panning adjustment.

  • -16 maps the parameter to the inverted full MIDI range
  • 15 maps the parameter to the nearly the full MIDI range
The documentation for this struct was generated from the following file:
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