Document:Eureka - Amiga / Tiny Synergy Replay (TSR) Technical Notes

1 Table of Contents

2 Introduction

Tiny Synergy Replay (TSR) is a speed and size optimized replay format for the Commodore Amiga (tested on a rev6 Amiga 500).
The exporter in the Synergy sequencer works on an arbitrary stream of note/controller events and uses a simple compression scheme to identify and optimize recurring events.
TSR supports a (tiny) subset of the Eureka sampler, including
For performance reasons, many of the more complex features, like the keymap based sample zone selection, will be baked into the .tsr file during export.

3 MIDI Ports

Note and controller data received on MIDI ports vst_a:1 .. vst_a:4 is mapped to Amiga sound channels 1..4.

4 MIDI Events

Program ChangeSelect first Sample-Instrument that is assigned the given program number
Note OnPlay note. C-3..B-5 (after zone transpose) correspond to Protracker notes C-1..B-3
- Note numbers C-0 .. G-10 (0..127) can be used to select zones from multi-sample keymaps
- Velocity can be mapped to volume (via volume velocity amount, Vel)
- Velocity can be used to select zones from multi-sample keymaps
- Velocity can be mapped to sample offset (via sample offset velocity amount, OffV)
- Start sample offset can be randomized (via sample offset random amount, OffR)
Note OffStop note / start release phase (velocity is ignored)
PitchbendPitchbend (-1..+1 octave)
CC#1 ModwheelFilter multi-sample zones at note-on
CC#2 BreathWavetable X-Pos (normalized, 0..127)
CC#4 FootWavetable Y-Pos (normalized, 0..127)
CC#7 VolVolume (0..127 is mapped to Amiga volume 0..64)
CC#11 ExprJump to Loop (absolute values, i.e. 0=loop 0, 1=loop 1, 2=loop 2, ..)
CC#16 Gen1(Re-)trig Mod Sequencer 1 when >0 (Volume)
CC#17 Gen2(Re-)trig Mod Sequencer 2 when >0 (Pitch Fine Tune)
CC#18 Gen3(Re-)trig Mod Sequencer 3 when >0 (Pitch Coarse)
CC#19 Gen4(Re-)trig Mod Sequencer 4 when >0 (Loop Table Index)
CC#80 Gen5Volume ModSeq table (0..15)
CC#82 Gen7Freq Coarse ModSeq table (0..15) (e.g. for arpeggios)
Received MIDI Events

5 Program Number assignment

In order to mark a Sample Instrument for Amiga export, it must be assigned a unique MIDI program number (1..128, or 1..9, A..Z, a..z).
This is also used for switching samples via MIDI program change events.

6 Sample Replay

The Amiga replay supports regular (forward) sample playback as well as wavetable (granular) playback.

6.1 Limits (max zones)

Each Sample Instrument in Eureka consists of n sample zones.
The Amiga replay supports a maximum of 255 sample zones (sum total).

6.2 Loops

Each sample zone contains a loop table with an arbitrary number of loop entries (up to 85).
When the repeat count of the first loop is 1, the next loop will be queued for playback automatically.
A repeat count of 0 will play a loop indefinitely.
Loops can be switched while a sample is playing, either by using the CC#11 Expr MIDI controller (mapped to Jump To Loop Abs modmatrix target), or by using modseq #4.
Whether zone loops are queued or played immediately is controlled by the "jump to loop immediately" checkbox (I above the loop table).

6.3 Play-from-start

The Play-From-Start checkbox (Start, directly above the loop table) causes the sample to be played from the beginning before jumping to the loop.
I.e. for regular sample loops, only a single loop table entry is required (similar to Protracker).
When the checkbox is set to mixed mode, the sample will be played from the position defined by the offset of the last loop table entry.
This is mostly useful for multisamples.

6.4 DMA alignment

Keep in mind that even though the samples are 8bit, the Amiga sample DMA requires word-aligned sample offsets / lengths.

6.5 Wavetables

Wavetables use either a 1D, or a 2D layout. The cycle length range (CycleLen) is 8..1024 sample frames.

6.5.1 1D

1D wavetables consist of up to 128 cycles.
If the wavetable size exceeds 16 cycles, it must be aligned to a multiple of 16.

6.5.2 2D

2D wavetables consist of up to 256 cycles (1x1 .. 16x16).

6.6 Glide

When glide is enabled in a sample zone (mode=Time(lin)), the glide speed will be mapped to a 4bit glide_speed value during export (see glide_speed_tbl in the replay). The range is 7.5 - 7680 milliseconds. Separate up and down glide speeds are supported.
Note glides are activated by playing overlapping notes.
glide is calculated in linear note-number space

6.7 Volume Ramp fade in

When the volume ramp up time (Rmp) is greater or equal than 16 millisecs, a short fade-in (6 replay ticks) will be applied during Amiga replay.
the exporter sets a flag, i.e. the actual ramp up time in the editor does not matter (it should be 16 to make it sound as close as possible to the HW replay)

7 Sample Instrument Initialization

7.1 amiga_init

The amiga_init page command (status bar command line) prepares a regular init patch for TinySynergyReplay (TSR) use.
For example, the sample rate will be set to 16574 Hz (middle C-5) and the mod matrix will be set up to route the four mod sequencers and map the MIDI performance controllers.
do not change the mod matrix routing manually, the exporter relies on the exact order of entries

7.2 editable modmatrix entries

7.2.1 volume, pitch fine and coarse amounts

The amount setting of entries 2, 6, and 10 may be edited and is used for scaling the modsequencer step values during export.

7.2.2 manual or LFO wavetable position

Manual vs LFO-controlled wavetable position modulation is selected by toggling modmatrix entries 11+12 and 15+16 (mutually exclusive).

8 Envelopes and LFOs

The regular bezier-curve envelopes and volume / freq LFOs must NOT be used (they are too complex for the 7 MHz 68000 CPU in an Amiga 500).
The only exception to this is the volume envelope release time (R in Vol widget row).

8.1 Mod Sequencers

The mod sequencers are used as follows:
Mod sequencer features supported by the Amiga replay:

8.2 Pan and Aux wavetable LFOs

The Pan and Aux LFOs are used for wavetable x / y position modulation (when enabled in the mod matrix).
The Amiga replay supports

9 Cycle Sample Synthesis

Each Sample Instrument (Sample Bank) stores up to 32 Cycle synth patches which are processed in order of occurence.
Patches without valid target zone assignments will be skipped.
When the zone double-click mode (toggle button right next to zone table) is set to S, double-clicking a zone opens the patch source code window. Setting the mode to M brings up the main patch window (param sliders) instead.
See the Cycle Manual for a detailed description of the Cycle script syntax.

9.1 Render Area

The sample synthesis target area is determined by the last entry in a zone's loop table.
it's sometimes useful to create a dummy zone that's never audible and simply serves to setup a render area. this can be achieved by e.g. setting the zone's velocity range (LV and HV) to 0

9.1.1 Resizing a render area

Copy and paste (or cut) sample data within a zone loop area to increase (or decrease) its size and automatically shift all following zones as required.

9.1.2 Initial waveform size

The page command resize_waveform <x> <y> resizes the waveform to <x> * <y> sample frames.
Click into the status bar and type res followed by cursor down to initiate the command.

9.2 Reorder zones

A sample instrument's Cycle synth patches can be reordered to match the zone order. Choose SampleSynth: Reorder patches by zones from the zone table context menu (RMB click).

9.3 Cloning zones and synth patches

Hold lshift while hold-clicking the + button of the zone table to clone a zone and its sample synth patch.
The new zone will be assigned a new render area and the waveform will be resized when necessary.

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Document created on 19-Aug-2023 23:25:43