foo_vis_vumeter

foo_vis_vumeter is modern reimplementation of the analog VU meter component by DRON. It renders using DirectX 12, falling back to DirectX 11 under Wine.

Features

• Uses DirectX 12 (Direct3D 12, DXGI 1.6, Direct2D 1.3, DirectWrite 1.3) for rendering.
  • Under Wine or Proton, renders with DirectX 11 (Direct3D 11.1) instead which omits some DirectX 12 features.
• Supports VUEditor-generated .bin files. Refer to the ".bin File Specification", "foobar2000 .rar Specification" and "foobar2000 .7z Specification" sections below.
• Supports AIMP analog .zip skins. Refer to the "AIMP Analog .zip Specification" below.
• Supports AIMP LED .zip skins. Refer to the "AIMP LED .zip Specification" below.
• Includes many fine-tuning options and modes.
• Implements controls through the mouse context menu.
• Provides additional configuration options through the tuning and mixing dialogs.
• Supports the Default User Interface (Default UI) and the Columns User Interface (Columns UI).
• Implements COM Automation through ActiveX objects.
• Delivers 32-bit and 64-bit x86 component configurations as well as ARM64EC.

Verification

• Tested on foobar2000 2.25.10 (x86 64-bit) and Microsoft Windows 11 (Build 26200).
• Tested with foobar2000 v2.25.10 (x64) under Proton Experimental (experimental-11.0-20260713 -- Wine 11.0):
  • Direct3D 11 via DXVK v3.0.1, HLSL compiled through vkd3d, running at Direct3D feature level 11_1.
  • Vulkan 1.4.350 on Mesa/RADV 26.1.99.
  • Verification machine: AMD Navi 33 (RDNA 3) GPU on SteamOS 3.8.24 (build 20260716.2, kernel 6.16.12-valve).
• Built for foobar2000 2.0 and later (2025-03-07) with latest Windows 11 SDK (10.0.28000.2114) and MSVC (14.51).

Run Requirements and Installation

• Requires foobar2000 2.0 or later.
• Requires Windows 10 or later due to DirectX 12.
  • Falls back to the WARP software rasterizer if no DirectX 12-compatible adapter found.
  • Under Wine or Proton, renders with DirectX 11 through DXVK.
• Download foobar2000 and install.
• Download the installation file (foo_vis_vumeter.fb2k-component) from the component page.
• Import foo_vis_vumeter.fbk2-component into foobar2000 using the File > Preferences > Components > Install... menu item.
• Download and extract panels or skins into this component's directory of foobar2000. This should be <foobar2000 profile folder>\vumeter.

Panels or Skins

The panels or skins files define the visualizations.

The foobar2000 component is not packaged with any panels. It supports various formats, namely foobar2000 .bin files, AIMP analog .zip skins and AIMP LED .zip skins.

Use these references to find community-made skins or create new ones using VUEditor:

• foobar2000 VU Meter Skin Gallery: A collection of skins compiled and curated by tom2tec.
• Custom Skin Thread (in Russian).
• Pointer Pickmeter (foo_vis_vumeter.dll) Thread by DRON with download links to VUEditor.zip (in Russian).
• AIMP Analog Meter (Plugin Skins) Thread (in Russian): Another collection of skins collected and curated by Artem (AIMP main developer).
• AIMP LVU Thread (in Russian): LED skins and editor by xrEngine.
• Some newly developed panels have been posted to the foo_vis_vumeter thread in the HydrogenAudio Forum.

Usage

The component is controlled via the context menu, accessible by right-clicking anywhere on the component window. In addition, fine tuning can be performed by using the mouse wheel.

What the mouse wheel controls is selected through the "Tuning" menu. If the changes result in bad state, use the "Options > Reset" option. The selected tuning mode value can be reset to its default using middle click.

In the context menu there are a few symbols placed next to some options. These are their meaning:

• Circle: an option that is mutually exclusive with its neighbors.
• Square: a selection that is mutually exclusive with its neighbors that is currently tunable by the mouse wheel.
• Eighth Note with Triangle: a selection has been made in a child/nested menu.
• Check Mark: a Boolean option that is enabled when checked and disabled when unchecked.
• Right Caret: there is a nested menu that will open on mouse hover.
• Bold Text: this options is the default action, double clicking the window performs it.
• Grayed Text: this option is invalid at the present time or disabled.

What follows are the different menu categories with a short explanation of each option.

At the very top of the context menu, the current resolution of the loaded panel is displayed as a grayed informational item. If no panel is loaded, it shows a corresponding message.

Layout:

• Left + Right (H): displays the left panel and right panel abutted side-by-side.
• Left + Right (V): displays the left panel abutted above the right panel.
• Left: displays only the left panel.
• Right: displays only the right panel.
• Mono: displays only the left panel and the needle shows a mixed-down version of the audio.
• Lock Aspect Ratio: locks the panel or skin to the native dimensions' ratio instead of filling the window.

Mode:

• Stereo: the default and shows discrete left and right channels. In multi-channel audio, the left channels are mixed down into one with specific weighing to be displayed in the left panel and similarly with the right channels for the right panel. The center and LFE channels are mixed into left and right with an even share going into each.
• Sum (Left + Right): shows the average of the sum of the left and right channels.
• Sum (Left || Right): shows either the left or right channels, whichever is greater.
• Mid/Side: shows mid and side components of the audio signal. Mid is shown in the left panel and is calculated as (left + right) / 2. Side is show in the right panel and is calculated as (left - right) / 2. Same downmixing into left and right channels for multi-channel audio as the Stereo mode applies before mid and side components are calculated.

Levels:

• RMS: the default and calculates root mean square of the samples in the sample window.
• Peak: finds the highest (absolute value) sample in the sample window.
• Mixed: uses "RMS" for the needle/pin or main display element and, if the panel includes them, uses "Peak" for the LEDs/lamps.
• Loudness (LUFS): calculates K-weighted momentary loudness (a 400 ms sliding window) in LUFS as prescribed in Rec. ITU-R BS.1770-5 and EBU R 128-2023 using the libebur128 library. Stereo output meters the left and right channels independently (each needle reflects its own channel loudness); downmixed or mono output shares a single combined measurement.

Movement:

• No Inertia: applies no post-processing to the needle movement.
• ODE Roots: uses the roots of the mass-spring differential equation to simulate the needle movement.
• VU Ballistics: the default and models standard ANSI/IEC VU meter ballistics as a second-order system. The tuning dialog has "Settle" and "Overshoot" parameters that are only enabled when this movement mode is selected. Settle (the rise/fall time to 99% of the target in milliseconds) can range is [50, 1000] ms (default is 300 ms) and Overshoot (a percentage of the target) from [0, 25]% (default is 1.3%; standard VU is 1-1.5%).
• Spring-Mass-Damper: uses the second-order roots of a spring-mass-damper system to simulate the needle movement. The tuning dialog has "Speed" and "Damping" parameters that are only enabled when this movement mode is selected. Speed range is [0.3, 2.0] (default is 1.0) and damping [0.5, 1.1] (default is 0.7).
• Curve Fit: moves the needle on top of a precomputed exponential curve based on the sample rate and frame time. When this movement mode is selected, the "Window" tuning parameter range is restricted between 30 ms and 120 ms.

Decay:

• Slow: sets the decay factor to 0.0075.
• Normal: sets the decay factor to 0.01.
• Fast: the default and sets the decay factor to 0.015.

Tuning (mouse wheel-controlled):

• Zero: sets the offset in frames from the default zero frame. Only applies to foobar2000 .bin panels. Default is 0 and the range is [-128.0, 512.0]. If:
  • Ctrl key is held down during the mouse wheel scroll, the step size is 100.
  • Shift key is held down during the mouse wheel scroll, the step size is 10.
  • Left Alt key is held down during the mouse wheel scroll, the step size is 0.1.
  • No key is held down during the mouse wheel scroll, the step size is 1.
• Range: compresses the range of the needle drawing space. Only applies to foobar2000 .bin panels when a level other than Loudness (LUFS) is selected. Default is 0 and the range is [0.0, 2.0] in steps of 0.01.
• Decay: sets how fast the needle falls per frame. Can also be set to predetermined values in the "Decay" menu. Default is 0.015 and the range is [0.0075, 0.03] in steps of 0.0005. Note: the tooltip display value is multiplied by 100.
• Rise: sets how fast the needle rises per frame. Default is 0.25 and the range is [0.01, 0.80] in steps of 0.01.
• Jitter: sets the minimum loudness change threshold needed for the needle to move. Default is 0 and the range is [0.0, 0.050] in steps of 0.001. Note: the tooltip display value is multiplied by 10.
• Gain: sets the preamplifier gain in dB. Default is 0 and the range is [-60.0, 60.0]. If:
  • Ctrl key is held down during the mouse wheel scroll, the step size is 10.
  • Shift key is held down during the mouse wheel scroll, the step size is 0.1.
  • Left Alt key is held down during the mouse wheel scroll, the step size is 0.01
  • No key is held down during the mouse wheel scroll, the step size is 1.
• Window: sets the sampling window size in milliseconds. Default is 64 and the range is [10.0, 400.0] in unit steps.
• FPS: sets the maximum number of frames rendered per second. Default is 60 and the range is [24.0, 60.0] in unit steps.
• Corner: sets the default corner radius width in pixels of the skin image size. Can also be set to enabled or disabled from the "Options" menu. Default is 16 and the range is [0.0, 32.0] in steps of 1.6.

Options:

• Downmix Channels: instructs foobar2000 to combine all channels into one. This occurs in the player before any of this component's processing. It is disabled by default.
• Automatic Gain Control: automatically adjusts the metered level toward the 0 VU reference so quiet or loud material sits around the mark. It is disabled by default.
• Needle Correction: applies a needle-to-frame linearity correction for panels/skins whose frames are not linearly spaced, improving needle accuracy. It is enabled by default.
• Rounded Corners: sets the corner tuning option to 0.0 (unchecked) or 16.0 (checked and default).

• Disable Tuning: disables the tuning menu and makes the component ignore the mouse wheel. The tuning menu is enabled by default.
• Disallow Fullscreen: disables fullscreening through mouse, menu and keyboard. Fullscreen toggling is enabled by default.
• Multi-Monitor Fullscreen: sets the fullscreen mode to span across all screens instead of only the single screen where the player is active. This option is only available when multiple monitors are connected and not already in fullscreen.
• Remove Background: removes the edge-sampled background and simply uses a dark or light mode default color. By default the sampled background is shown.
• Enable Transparency: enables transparency in Columns UI for panels that support it such as JSP3 and JSplitter. Note that this mode incurs a heavy performance penalty when enabled; it is especially noticeable during windowing events such as resizing. As such it is disabled by default.
• Ignore Defaults: ignores the defaults set in .ini files that may accompany the .bin files, both loose and archived in .rar or .7z, and disables automatic layout selection from filename layout suffixes. Defaults are not ignored by default.
• Equivalent Pause and Stop: makes pausing and stopping equivalent. By default, when disabled and paused, simulation state is held. When enabled, regardless of whether paused or stopped, the simulation decays to zero.
• Freeze: freezes video frame. It is not enabled by default.
• Show Counter: displays a frame counter on the top right. It is not shown by default.
• Screensaver Mode: switches skins/panels automatically after a specific interval. The switching occurs only within the same group (folder). The switching interval (period) of this mode is controlled through a slider in the tuning dialog; the default value is 18 seconds and the range is [1, 1200] seconds. The mode is disabled by default.
• Vertical Synchronization: disabled and not functional. When an easter egg mode is active, this option changes to "Easter Egg" and can be used to deactivate it.
• Rescan: rescans panels directory.
• Reset: resets all options to their defaults except layout/visual options.

Configure: opens a dialog box with the tuning options.

Mix: opens a dialog box with the channel level mixer board.

Explore: opens the profile directory in Windows Explorer.

Fullscreen: toggles the component between fullscreen mode and embedded or windowed mode. Keeps the screen on and stops the screensaver from starting during fullscreen. In fullscreen mode, the mouse cursor is automatically hidden after 1 second of inactivity and reappears on mouse movement or context menu interaction.

The Fullscreen option is bolded because it is the double-click default.

The different panels/skins found during the scan of the <foobar2000 profile folder>\vumeter directory appear in lexicographical order (directories first) below the "Fullscreen" toggle.

There are some options under: Preferences > Advanced > Visualisations > VU Meter:

• Debug output: <unchecked>. Enables debug console logging.
• Optimize memory: <unchecked>. Unloads resources when the component window is hidden.
• Render backend: <0>. Selects the graphics backend. Automatic uses Direct3D 11 under Wine/Proton and Direct3D 12 on Windows; it can also be forced to Direct3D 12 or Direct3D 11.
• Panels directory: <empty> (implies <foobar2000 profile folder>\vumeter\ when empty). Supports %fb2k_profile_path% and environment variables (also enclosed between %; DOS-style).
• Degreelessness: (<empty>; untested). If the MD5 hash of the entered string matches a specific digest, the teapot easter egg mode is activated on launch.

Tuning Mode Selection

The currently selected tuning parameter is denoted by a square symbol under the context menu's Tuning popup. The selected tuning parameter can be changed by three main methods. The first is directly through selecting the desired one in the context menu. The second is using a modifier key and the vertical mouse wheel together to cycle through the parameters in menu order. The modifier key that must be held down while the vertical mouse wheel turns is one of Esc, Right Alt or AltGr. The third is to use the horizontal mouse scroll wheel. As the tuning parameter changes, the mouse tooltip should display the active one and its current value.

Once again, the selected tuning mode value can be reset to its default using middle click and all tuning parameters will fall back to their defaults if the Options > Reset option is used.

Note: selecting a parameter simply means this is the one that will be affected by the mouse wheel and middle mouse click. The combination of all settings and tuning parameter values determines the visualization's behavior appearance.

Tuning Dialog Box

Tuning can also be done through the context menu's Configure dialog box. Notes:

• Only one dialog box can be open at a time and it is modeless.
• The panel selection will only affect the instance from where the dialog was launched, whereas all of the other tuning parameters affect every instance.
• Changes are reflected in real time.
• Clicking "Cancel" or "X" (in the system menu bar) will undo any changes back to the state when the dialog box was opened. Either of these will also close the dialog box.
• Clicking "Reset" will revert all options to their default values (exactly equivalent to the reset option in the context menu).
• Clicking "Font" will open a font selection dialog for customizing the FPS counter text properties (family, style, size, weight, color, and opacity). The dialog shows a live preview. The counter text defaults to opaque white.
• Clicking "OK" will keep the changes and close the dialog box.
• All combos, buttons, sliders and edit boxes include tooltips and are tab stops.
• Sliders can be controlled using the mouse by dragging the slider or by the mouse wheel. Also using the keyboard's arrow keys and Home/PgUp/PgDn/End.
• When the dragging a slider with the mouse, the edit box value and the tune value itself are updated only when the dragging ends (i.e., left mouse button released).
• Editing the tune value with the keyboard directly might be difficult due to the real-time validation.
• The dialog box takes on the default theming colors based on light or dark mode selection in foobar2000.

Mixer Dialog Box

Channel level mixing can be customized through the context menu's Mix dialog box. Notes:

• Only one dialog box can be open at a time and it is modeless.
• The mix will affect every instance, however the color box only affects the instance where the dialog was launched.
• The sliders have their loudest setting (0 dB) at the top and their quietest (-12 dB) at the bottom.
• While audio is playing, each slider's thumb is colored to indicate whether that channel carries signal in the current track: green when the channel is present and gold/amber when it is absent. When nothing is playing, the sliders use the default theme thumb.
• The color box will only appear for .bin panels. It contains the edge-sampled RGB hexadecimal background color. It can be changed to any other valid color, overriding the automatically-sampled color.
• The "Enable mixer" checkbox is automatically selected and deselected. It is selected when the level mode is not Loudness (LUFS).
• Clicking the "Default" button will reset the mixer sliders to their default values and the color box to the edge-sampled value.
• Clicking "Cancel" or "X" (in the system menu bar) will undo any changes back to the state when the dialog box was opened. Either of these will also close the dialog box.
• Clicking "OK" will keep the changes and close the dialog box.
• The left channels are front left (L) [0 dB], back left (BL) [-3 dB], front center left (FCL) [-6 dB], side left (SL) [-3 dB], top front left (TFL) [-3 dB] and top back left (TBL) [-3 dB].
• The right channels are front right (R) [0 dB], back right (BR) [-3 dB], front center right (FCR) [-6 dB], side right (SR) [-3 dB], top front right (TFR) [-3 dB] and top back right (TBR) [-3 dB].
• The center channels are front center (C) [-3 dB], low frequency effects (LFE) [-10 dB], back center (BC) [-6 dB], top center (TC) [-6 dB], top front center (TFC) [-6 dB] and top back center (TBC) [-6 dB].

Layout Suffix

Skin filenames can include a layout suffix using the pattern N where N is a number from 0 to 4 corresponding to the layout modes (0 = Left+Right H, 1 = Left+Right V, 2 = Left, 3 = Right, 4 = Mono). When a skin with a layout suffix is loaded, the layout is automatically set to the specified mode. The suffix is removed from the display name in the context menu. This behavior is disabled when "Ignore Defaults" is enabled.

Main Menu

The component adds a dynamic menu item under foobar2000's main menu (hidden by default; hold Shift when opening to reveal). It displays the panel groups and skins, along with "Previous" and "Next" navigation commands per group.

Gestures

The press-and-tap touch gesture switches skins/panels within the same group.

Horizontal Mouse Wheel, Button 4 and Button 5

The horizontal mouse wheel and buttons 4 and 5 can be used to cycle through the selected tuning option. Be aware that buttons 4 and 5 might have other side-effects in the player such as moving to the next or previous track.

Screenshot

A screenshot can be taken by holding Ctrl and left-clicking on the component window. The screenshot is saved as a PNG file in the screenshots subfolder of the panels directory. Files are named sequentially (shot_00.png, shot_01.png, etc.).

Keyboard Shortcuts

As with the mouse buttons, be aware that any custom keyboard shortcuts set in the player can alter or prevent the component from reacting to these.

• Alt + Enter: toggles fullscreen.
• Esc: exits an easter egg mode (teapot or text entry).
• Backspace: removes the last character in text entry mode.
• Delete: clears all text in text entry mode.
• Page Up / Page Down: changes the texture in teapot mode.

Running foobar2000 under Proton

When foobar2000 is installed as a non-Steam title, it can be launched against its Proton prefix directly from the command line. Replace <id> with the app's compatdata identifier and adjust the Proton build path if you use a different Proton version.

STEAM_COMPAT_DATA_PATH="/home/deck/.steam/steam/steamapps/compatdata/<id>" \
STEAM_COMPAT_CLIENT_INSTALL_PATH="/home/deck/.steam/steam" \
"/home/deck/.steam/steam/steamapps/common/Proton - Experimental/proton" run \
"/home/deck/.steam/steam/steamapps/compatdata/<id>/pfx/drive_c/users/steamuser/foobar2000/foobar2000.exe"

• STEAM_COMPAT_DATA_PATH points at the app's compatdata/<id> directory; its pfx subfolder is the Wine prefix used for the fonts and scaling tweaks below.
• STEAM_COMPAT_CLIENT_INSTALL_PATH points at the Steam installation root.
• The final argument is the path to foobar2000.exe inside the prefix.

Fonts under Wine and Proton

The dialogs and the on-screen frame counter request the "Segoe UI" font. Windows ships this font, but Wine and Proton do not, so they substitute a default sans-serif face (often Liberation Sans or the host desktop font). To restore a Segoe UI-like appearance, use one of the following approaches. In each case, restart foobar2000 afterward.

1. Copy Segoe UI into the prefix (most faithful; requires a Windows license). Locate the Wine/Proton prefix foobar2000 runs in. For a Steam/Proton shortcut this is ~/.steam/steam/steamapps/compatdata/<AppID>/pfx; for plain Wine it is $WINEPREFIX (default ~/.wine). Copy the Segoe UI family (segoeui.ttf, segoeuib.ttf, segoeuii.ttf, segoeuiz.ttf, segoeuil.ttf, seguisb.ttf, segoeuisl.ttf, seguibl.ttf and their italics) from a licensed C:\Windows\Fonts into <prefix>/drive_c/windows/Fonts/.
2. Use Selawik (open, metric-compatible). Microsoft's MIT-licensed Selawik font is a drop-in, metric-compatible substitute for Segoe UI. Install selawik*.ttf into the prefix Fonts folder, then map the name: under the HKEY_CURRENT_USER\Software\Wine\Fonts\Replacements registry key, add a string value named Segoe UI with data Selawik.
3. Substitute a font already on the system. Using the same Wine\Fonts\Replacements key, map Segoe UI to a similar installed face such as Open Sans, Noto Sans or Liberation Sans.

Note 1: The Wine\Fonts\Replacements key is also where to look for (and delete) an existing Segoe UI (and Segoe UI Semibold) mapping if a copied font is not being picked up. A stray mapping to a serif face such as Times New Roman is a common reason the dialogs render in a serif font even when Segoe UI is installed.

Note 2: Copying Segoe UI from a licensed Windows installation for personal use is permitted; it may not be redistributed, which is why Selawik exists for bundling a prefix.

Window Scaling under Wine and Proton

If the dialogs render too small or too large under Wine or Proton, adjust the prefix's DPI. Scaling is controlled through winecfg.

1. Open winecfg for the prefix foobar2000 uses:
   • Plain Wine: WINEPREFIX=<prefix> winecfg.
   • Winetricks GUI: run winetricks, select the prefix, then choose Run winecfg.
   • Proton (Steam): run protontricks, select the prefix, then choose Run winecfg.
2. In winecfg, open the Graphics tab and change the Screen resolution DPI value. 96 dpi is 100%; common steps are 120 (125%), 144 (150%) and 192 (200%). Higher values enlarge the entire UI - dialogs, fonts and the meter chrome; lower values shrink it.
3. Click Apply / OK.

Note: The DPI value is stored in the registry at HKEY_CURRENT_USER\Control Panel\Desktop\LogPixels (a decimal REG_DWORD, e.g. 120), which you can also set directly with wine regedit instead of winecfg.

Dynamics

The needle movement can be approximated using the following formula: display = old +/- (e ^ (new - old) - 1) * rise/decay. The rise or decay factor limits how far the needle can move per frame or iteration of the calculation.

The needle position, frame number in foobar2000 .bin panels or angle in AIMP analog .zip skins, is calculated using the point-slope equation referenced to the zero dB frame or angle. For the AIMP LED .zip skins, the "light" fill is calculated by interpolating between the points in the dbs parameter's array using Catmull-Rom splines.

Needle Behavior Derivation Methodology

Used a circuit of a stereo VU meter, tracing the PCB and translating all the component values of the driving circuit into a SPICE netlist. The netlist was simulated to get the step/transient and impulse responses of the "system." Since the VU meter face plate is logarithmic, the circuit uses analog differentiator, integrator and summer circuits. To validate the netlist simulation correctness, various points of the working circuit were probed with an oscilloscope.

With the characteristics of the driving circuit in hand, turned attention to the needle. The needle can be modeled as a mass-spring-damper system. So, setting up the ODE for the system (with some minor guesses) provides the behavior characteristics of the needle. This is a common second-order system with known roots.

The needle was set up underdamped. The transient and impulse response targets of the SPICE simulation (which come from the voltage levels closest to the visualization audio levels provided by foobar2000) are exposed as higher-level abstractions called "rise" and "decay"--where larger numbers mean faster--and "jitter", a control on the minimum change threshold. These knobs drive the ODE Roots movement. For a standards-based alternative, the default VU Ballistics movement derives the ANSI/IEC second-order response directly from a settle time and overshoot (see the Movement section).

This methodology only provides an approximate model of the analog behavior of the needle in a discrete simulation. Although the derivation was detailed, the needle movement of this component is not and will never be an accurate duplicate to its real-world analog. However, using the tuning knobs provided along time and experimentation it should be possible to create a pleasing ballistic needle movement.

.bin File Specification

Panel Specification
===================

Reverse Engineer: Jimmy Cassis
Date: 2024-10-01

This specification defines the format of the BIN file.

Panel File Format
-----------------

The files in this format use ".bin" extension.

The panel file begins with a header.

The panel file format layout:

Offset     Size    Description

  0          2     Bitmap width (16-bit unsigned integer, little-endian), between 2 and 4096
  2          2     Bitmap height (16-bit unsigned integer, little-endian), between 2 and 4096
  4          2     Frame count (16-bit unsigned integer, little-endian), between 2 and 1024
  6          2     Zero dB frame (16-bit unsigned integer, little-endian), between 0 and 1024
  8          n     Needle delta offset list (array of 32-bit unsigned integer offsets, little-endian), `n` is "frames * 4" and the first entry must be greater than or equal to 32; note that some offsets might be repeated due to the "knots" interpolation.
  8+n        p     Background image bitmap pixel array (BI_RGB format [B8G8R8A8 UNORM], 32 bits per pixel, little-endian), `p` is "width * height * 4", format below
  8+n+p      l     Optional, lamp delta offset list (array of 32-bit unsigned integer offsets, little-endian), `l` is "frames * 4"
  8+n+p+l    d     Needle delta arrays (variable size, offsets are big-endian, deltas are BI_RGB and apply per channel), `d` is variable, format below
  8+n+p+l+d  a     Optional, lamp delta arrays (variable size, offsets are big-endian, deltas are BI_RGB and apply per channel), `a` is variable, format below

The total size of the file is: 8+n+p+l+d+a
The total size of the file must be greater than: 8+n+p

The bitmap pixel array layout is as follows (address _decreases_ from left-to-right) and arranged in top-down order:

                     +-------------------------+-------------------------+-------------------------+-------------------------+
Sample Length:       |            8            |            8            |            8            |            8            |
Channel Membership:  |          Alpha          |           Red           |          Green          |           Blue          |
Pixel Bits:          |  A  A  A  A  a  a  a  a |  R  R  R  R  r  r  r  r |  G  G  G  G  g  g  g  g |  B  B  B  B  b  b  b  b |
Bit Number:          | 31 30 29 28 27 26 25 24 | 23 22 21 20 19 18 17 16 | 15 14 13 12 11 10  9  8 |  7  6  5  4  3  2  1  0 |
                     +-------------------------+-------------------------+-------------------------+-------------------------+
                      ^                         ^
                      |                         |
                      |                         + less significant byte
                      + more significant byte

The needle and lamp delta arrays use the following format:

- For every frame there is a 2-byte big-endian offset while the most significant bit (MSB) of the even byte is unset.
- If the MSB for the even byte is set, it indicates a count (excluding the MSB) of the number of pixel channels to override starting at the offset in the pixel array indicated by the sum of all the previous 2-byte offsets.
  * Note that the offset might not necessarily start or end at a pixel boundary.
- Repeat, calculating a new offset from the end of the final overriden pixel until the even byte MSB is set and the count is zero (0x80).

Worked example for the needle delta array (address _increases_ from left-to-right):

             +-----------------------------------+-----------------------+-----+-----------------------------------------------------------+-----+---------...---+
Offset Sum:  |             174272                |           7           | 1489|                           19                              | 1481|     23  ...   |
Offset:      |32768+32768+32768+32768+32768+10438| 7| 0| 1| 2| 3| 4| 5| 6| 1488|19| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9|10|11|12|13|14|15|16|17|18| 1480|23| 0| 1|...| 0|
Bytes:       |7F FF 7F FF 7F FF 7F FF 7F FF 28 BF 87 8A 8B 87 00 E0 E2 DE 05 D0 93 B1 B2 AE 00 69 6A 67 00 6B 6D 68 00 B8 B9 B6 00 E0 E2 DF 05 C8 97 E6 EE ... 80|
Pixel Bits:  |^^ **                              |   Bb Gg Rr Aa Bb Gg Rr|     |   Bb Gg Rr Aa Bb Gg Rr Aa Bb Gg Rr Aa Bb Gg Rr Aa Bb Gg Rr|     |   Bb Gg ...End|
             +-|--|------------------------------+-----------------------+-----+-----------------------------------------------------------+-----+---------...---+
               |  |
               |  + more significant byte
               + less significant byte

Notes
-----

When drawing, ignore the alpha channel.

Extensions
----------

1. Separate Left and Right Panels

  By default, the panel file represents both the left and the right panels.
  If the file format is repeated at the end of the delta arrays, it is assumed that the first format corresponds to the left panel and the second format corresponds to the right panel.
  The file formats can be concatenated uncompressed into one file. Alternatively, individually compressed files can be concatenated (keep the same compression scheme for both).
  Another method to provide separate left and right panels is to provide a pair of files where the left panel file ends in `1.bin` and the right panel file in `2.bin`.

2. Transparency (Alpha Channel)

  By default, the alpha channel is ignored.
  If the alpha channel is not to be ignored (BI_BITFIELDS format [B8G8R8A8 UNORM], 32 bits per pixel, little-endian), set bit 7 (the most significant bit) of the upper byte of the zero dB frame in the header.

3. Bottom-up Background Bitmap Pixel Array.

  By default, the bitmap pixel array is assumed to be in top-down order.
  If the bitmap pixel array is arranged in bottom-up order instead of top-down order, set bit 6 of the upper byte of the zero dB frame in the header.

Additional .bin Notes

• Can be bzip2-compressed (recommended), LZMA-compressed, XZ-compressed (LZMA2), Gzip-compressed, Zstandard-compressed, LZ4-compressed, Lzip-compressed, Brotli-compressed or uncompressed.
• Can use needles or lamps (LEDs), or both.
• Can contain a single meter for left and right channels or separate left and right meters. See Extension 1.

Warning: Identifying LZMA-compressed heuristic is limited; especially if the skin was compressed outside of VUEditor. Therefore it is possible to confuse an uncompressed .bin file of any width less than 225 with a LZMA-uncompressed one. Using a bzip2-compressed file mitigates this issue since this scheme starts with an easily identifiable magic number.

AIMP Analog .zip Specification

• Must be ZIP-compressed and contain a skin.ini alongside corresponding PNG images at the root of the archive.
• Can contain a single panel for left and right channels or separate left and right panels.
• For single panel the images must be named 0.png (background), 1.png (needle), 2.png (glass) with optional 3.png (LED) and bg.png (wallpaper).
• For single panel all parameters must be specified under the VU section in the skin.ini file; the supported parameters are MinAngle, MinLevel, ZeroAngle, ZeroLevel, MaxAngle, MaxLevel, PivotPointX, PivotPointY, MobilityNegative, MobilityPositive, orientation, and dbs. The section and parameter names are case insensitive.
• For separate left and right panels the left panel images must be named l_0.png (background), l_1.png (needle), l_2.png (glass) with optional l_3.png (LED) and the right panel images must be named r_0.png (background), r_1.png (needle), r_2.png (glass) with optional r_3.png (LED). There can be an optional bg.png (wallpaper). The image names are case insensitive.
• For separate left and right panels, the left panel parameters must be specified in the skin.ini file under the VU_L section and the right panel parameters must be specified under the VU_R section. The supported parameters are the same as the single panel ones.

Note 1: MobilityNegative, MobilityPositive, and orientation parameters are currently unused.

Note 2: The dbs parameter array is optional and only used in skins that include an LED component in addition to the needle. As noted previously, the LED image is l_,r_,3.png.

Note 3: Missing parameters are assumed to be 0 or false.

AIMP LED .zip Specification (LVU)

• Must be ZIP-compressed and contain a settings.ini alongside corresponding PNG images at the root of the archive.
• The left panel parameters must be specified in the settings.ini file under the left section and the right panel parameters must be specified under the right section. The background must be specified in the bg section. The supported parameter in all 3 sections is png. The supported parameters in the left and right sections are orientation, start_point, finish_point, pos_x, pos_y, and dbs.
• The dbs image "dimension" can increase or decrease with the decibel level depending on whether the LED image is covered or uncovered.
• An orientation value of 0 specifies that the dbs dimension refers to width (i.e., horizontal). Conversely a value of 1 refers to height as the value that changes with the level (i.e., vertical).
• The image name must match the one given in by the png parameter for each section.

foobar2000 .rar Specification

• Must be RAR-compressed and contain a <filename>.bin file alongside an optional <filename>.ini file. Where <filename> must exactly match the name used as the base name of <filename>.rar. Further, these files must be placed in the root of the archive.
• The <filename>1.bin/<filename>2.bin naming pattern (with or without space between file name root and number) is also supported for individual L/R panels.
• The .bin file(s) contained in the archive must follow the .bin file specification outlined above and compressed, if desired, using a supported format.
• All customization parameters must be specified under the DEFAULT section in the <filename>.ini file; the supported parameters are fall, rise, singleMeter, peakLED, isVertical, curveAdj, and bgColour. The section and parameter names are case insensitive.

Note 1: fall and rise parameters are currently unused.

Note 2: The peakLED parameter being true sets Levels to _Mixed as soon as the panel is loaded. The singleMeter and isVertical parameters combine to set the Layout mode. The bgColour parameter sets the background color, overriding the edge color detection. The curveAdj parameter flattens the logarithmic curve by affecting the quadratic parameter.

Note 3: Missing parameters are assumed to be 0 or false.

foobar2000 .7z Specification

• Must be 7z-compressed and follow the same layout and rules as the .rar specification above, except that the archive uses the .7z extension. It must contain a <filename>.bin file alongside an optional <filename>.ini file, where <filename> must exactly match the base name of <filename>.7z, and both files must be placed in the root of the archive.
• The <filename>1.bin/<filename>2.bin naming pattern (with or without space between file name root and number) is also supported for individual L/R panels.
• The .bin file(s) contained in the archive must follow the .bin file specification outlined above and compressed, if desired, using a supported format.
• All customization parameters must be specified under the DEFAULT section in the <filename>.ini file; the supported parameters and their notes are identical to those of the .rar specification.

Standalone .ini File

• Similar to the .rar and .7z specifications, except that <filename>.bin and <filename>.ini are not archived together.
• <filename>.bin and <filename>.ini must live in the same folder.

COM Interface Specification

The component exposes COM interfaces for automation. The IVUMeter and IVUMeterWindow COM interfaces for managing and interacting with the foobar2000 VU Meter component. In foobar2000, these interfaces are mainly accessed through JavaScript.

Functions

com_get_interface

Retrieves a IVUMeter interface instance.

extern "C" __declspec(dllimport) HRESULT __cdecl com_get_interface(IVUMeter** pp);

Enums

LayoutEnum

Defines the layout options for the VU Meter window.

Interfaces

IVUMeter

Provides control and status for the VU Meter component.

IID: {9EBE6FDE-502B-4571-922F-5D5942A53638}

Properties

Functions

/----------------------------------------------------------------------------------------/

IVUMeterWindow

Represents a VU Meter window instance with properties for visibility, layout, and skin/panel configuration.

IID: {482C5F92-2D21-4F6F-9857-87C1D2C04344}

Properties

Functions

Configuration GUIDs

The component identifies itself, its preferences, and every persisted setting to foobar2000 through fixed GUIDs. These are internal identifiers of interest primarily to developers and for troubleshooting configuration state.

Entries marked Reserved are allocated but currently inactive; the GUIDs remain reserved so the identifiers are not reused. Type prefixes follow Hungarian notation: sz is a string, b is Boolean, and n is an integer.

Component Registration

Settings Controlled in Preferences Page

None. All persisted settings are exposed through the context menu, tuning/mixer dialogs, or advanced preferences rather than a dedicated preferences page.

Settings Controlled in Advanced Preferences

Options Showing in Main Menu

None.

State Settings Saved on Close and Restored on Launch

Controlled through the context menu or keyboard shortcuts.