Mockbird

The documentation covers these topics:

Command-line setup tool

Invoke mockbird for these functions:

• Get command line help using mockbird help
• List the synthsizer configuration by mockbird dump. As of version 0.1, running the tool without any parameter performs the same operation.
• List the definition of certain melodic programs by mockbird dumpprg <n> or mockbird dumpprg <m>-<n>. The syntax used for specifying the up to four layers of a program is described in Soundscape::InstrumentLayer
• Change the definition of a single melodic program by using mockbird loadprg <n>. The program definition may be on the command line or provided on stdin.
• Play a test tune to try modified programs by invoking mockbird play, optionally followed by a program number. If no program number is given, program 0 will be used.
• Reset the synthesizer using mockbird reset.

Note that mockbird uses 0-based program numbers as of version 0.1.

Library use

Construct a Soundscape::Card object to interface to the synthesizer. The documentation of that object contains further details.

Synthesizer architecture

Waveforms

The wavetable synthesizer uses a set of monophonic waveforms, which may be encoded as 16-bit linear PCM, 12-bit linear PCM or 8-bit linear or uLaw PCM. These waveforms may be looped.

The same wave data may be looped in different ways. In this case, one waveform definition includes the wave data, and other waveforms define different start, end, loop start and loop end positions referring back to the "primary waveform". These referring waveforms are called "alias waveforms".

Furthermore, there may be a map that dispatches to different waveforms depending on the key, which may be used to provide a kind of "MIP-mapping" for samples, or to provide different recordings for different key ranges. These dispatching pseudo-waveforms are called "wavemaps".

In higher layers, there is no distinction whether a waveform is a primary waveform, an alias waveform or a wavemap.

Patches

The parameters how to play a wave are specified in patches. Those patches include definitions of the playback rate, the volume, filter coefficients, two low-frequency oscillators and two envelope generators. Patches are still monophonic.

Layers

The top layer is melodic instruments (which are addressed as MIDI programs), which can refer to up to four patches, and drum instruments, which refer to a single patch.

Implementation status

At version 0.1 these features are implemented

• Sending MIDI data to the synthesizer
• Reassigning patches to melodic instruments

While these features are still missing

• Reassigning patches to drum instruments
• Reprogramming patches
• Redefining waveforms