V-MidsiderIn

What it is

V-MidsiderIn is a zero-latency stereo matrix that encodes a conventional left/right signal as Mid/Side. For every sample it writes Mid = 0.5 * (L + R) to the left output channel and Side = 0.5 * (L - R) to the right output channel. It has no width, level, or processing controls; its only parameter is Bypass.

Controls & parameters

The editor also shows a static encode matrix and processing-status display. These are not additional parameters.

Workflow / how to use it

1. Insert V-MidsiderIn at the start of a stereo effects chain.
2. Leave Bypass off to encode the signal. The left channel now carries Mid and the right channel carries Side.
3. Insert a stereo processor after it. Process the two channels as Mid and Side, or route them to separate processing paths.
4. Insert V-MidsiderOut after the M/S processing to decode the result to normal left/right stereo.
5. If the chain is being checked or compared, use Bypass with the understanding that it bypasses the encoder and leaves the signal in ordinary L/R form.

Use cases

• Encode-process-decode chains: Build an M/S EQ, compression, or other stereo-processing chain from ordinary stereo plug-ins by placing V-MidsiderIn before the processors and V-MidsiderOut after them.
• Mono and side checks: Treat the left output as Mid and the right output as Side, then monitor or process those paths separately to check the center and the stereo component.
• Width manipulation with V-MidsiderOut: Apply a separate level change to the Side channel between the pair, then decode with V-MidsiderOut. V-MidsiderIn itself does not contain a width control.
• Literal half-scale matrix work: The encoder uses one half of the sum and one half of the difference. The matching decoder adds and subtracts those values, so an untouched In-to-Out pair returns the original L/R signal at unity rather than adding 6 dB.

Specs & requirements

• Formats: AU and VST3.
• Audio I/O: Stereo input and stereo output are configured. The source layout validator also accepts matching mono input/output layouts, but the matrix runs only when at least two input and two output channels are present; a mono layout is therefore left unchanged.
• Latency: Zero processing latency. The processor reports a zero-second tail.
• Sample rates: No fixed sample-rate list is declared by the plugin source.
• Precision: Supports both FP32 and FP64 processing and follows the host’s active precision.
• MIDI: No MIDI processing is enabled.
• State: Bypass is stored as APVTS XML state. The plugin exposes one host program and does not implement preset programs.
• Platform: Workspace audio-toolbox build guidance targets macOS 10.15 or later.

Notes / caveats

• The matrix is normalized: Mid = 0.5 * (L + R) and Side = 0.5 * (L - R). Do not treat the encoder output as a raw, unscaled sum/difference signal.
• V-MidsiderOut is the exact inverse: L = Mid + Side and R = Mid - Side. No compensating gain change is needed for the untouched pair.
• Bypassing V-MidsiderIn passes ordinary L/R through; it does not produce an M/S signal.
• If V-MidsiderIn is used without a matching decoder, the output remains in M/S channel order and will not sound like conventional stereo when monitored as L/R.
• The conversion is an in-place, per-sample matrix with no parameter smoothing, metering, allocation, or delay in the processing loop.