A-Meter

Fwuzeem Audio A-Series

What it is

A-Meter is a level-monitoring plugin with stereo peak/RMS bars, peak hold, and an analogue-style VU needle. It is bit-perfect audio pass-through: the processor does not change the samples sent to the output. It copies incoming samples to a fixed visual ring buffer, and the editor calculates the displayed measurements on a 60 Hz GUI timer. The V-Shift control changes only the visual meter level; it never changes audio gain.

Controls & parameters

The V-Shift knob follows the house rotary range of pi*0.82 to pi*2.18 with a stop at the ends. At 0, the visual meter is at unity. A positive shift makes the display more sensitive to quiet material; a negative shift gives hot material more visual room. Neither setting is an audio gain control.

Peak and RMS modes use the bar display and show the complementary measurement as a marker. The display also reports peak, RMS, and crest values for the two channels. VU mode shows the two analogue-style needles; its scale labels 0 VU = -18 dBFS.

Workflow / how to use it

1. Insert A-Meter at the point where level needs to be observed.
2. Leave V-Shift at 0 when you want the displayed level to follow the unscaled signal.
3. Choose Peak for fast peak activity, RMS for a smoothed average level, or VU for the analogue-style response.
4. Choose a peak-hold time when transient history matters. Use Infinite for a persistent check, or Off for a live display.
5. Read the channel bars and numeric peak/RMS values while confirming that the audio path remains unchanged.

Use cases

• Gain staging by eye. Insert A-Meter before or after a processing stage and watch peak and RMS dBFS levels without placing a gain stage in the signal path. If the signal is hard to see, use V-Shift as display zoom rather than changing the track level.
• LUFS-free level watching. Use RMS or VU mode for immediate level supervision when an integrated loudness measurement is not required. A-Meter is a level monitor, not a LUFS meter, so it does not replace loudness metering.
• Peak-hold transient checking. Select 1 s, 2 s, or Infinite and watch the held marker while checking drum hits, plucks, edits, or other short events. Reset the view by selecting Off when a live reading is preferred.
• Visual ratio checking. Use whole V-Shift steps to inspect a quiet or hot section: +1 is a visual x2, and -1 is a visual x1/2. The corresponding audio remains unchanged.

Specs & requirements

• Formats: AU and VST3.
• Audio layouts: matching mono or stereo input and output layouts; the normal configuration is stereo.
• Processing: FP32 and FP64 audio processing are supported.
• Audio latency: no intentional audio delay; the visual ring buffer is not in the audio path. Tail length is 0 seconds.
• MIDI: no MIDI input or output; this is not a MIDI effect.
• Programs and state: one host program; parameter state is stored as APVTS XML.
• Platform target: macOS 10.15 or later.
• Build: use the shared CMake pipeline from the A-Meter folder (cmake -B build, then cmake --build build).

Notes / caveats

• A-Meter performs no audio DSP. Its output is the input passed through unchanged, apart from normal host bus-layout handling.
• Meter calculations run on the GUI side from a fixed 32,768-sample stereo ring buffer. The visible surface updates at 60 Hz, so the display is an analysis view rather than a sample-accurate output monitor.
• V-Shift is visual-only. It changes the samples used for the meter calculation and therefore can also change the visual clip indication; it cannot prevent or create clipping in the audio output.
• Peak, RMS, and VU are different display responses. VU mode uses smoothed RMS behavior and an analogue needle; it is not a separate audio signal or a LUFS calculation.