User Guide — Julio Monroy Online Meter
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Loading a File
Drag and drop any audio or video file onto the window, or click āø OPEN to load it from your computer.
Supported formats: MP3, WAV, FLAC, OGG, MP4, MKV, MOV.
Audio processing is 100% local in your browser — your file never leaves your computer.
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Playback Controls
ā¶ / āø — Play / Pause
ā¹ — Stop (returns to the beginning)
ā® — Restart from the beginning
āŖ + Slider — Volume control
Progress Bar — Click anywhere to jump to that position
VIS / VID (visible only when a video file is loaded)
Toggles between the pure visualizer and the video with the visualizer displayed as an overlay.
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Keyboard Shortcuts
Spacebar — Play / Pause
← → — Rewind / Fast-forward 5 seconds
↑ ↓ — Increase / Decrease volume
V — Toggle Video / Visualizer mode (when a video is loaded)
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Understanding the Meters
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PEAK
Displays instantaneous peak levels for each channel in dBFS.
HOLD retains the highest recent peak.
HLD L/R shows the highest peak reached by the song since playback began.
If values approach 0 dBFS, you are very close to clipping.
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RMS
Represents the perceived average level.
SHORT 300ms shows RMS energy measured over the last 300 milliseconds, providing a sense of immediate impact and loudness.
SONG AVG displays the cumulative average RMS level across the entire playback session.
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LUFS (K-weighted)
Measures loudness according to the ITU-R BS.1770 standard.
S-T (Short-Term) displays loudness over the last 3 seconds.
INT (Integrated) displays the integrated loudness of the entire song.
Typical loudness targets:
* Streaming platforms (Spotify, Apple Music, YouTube): −14 LUFS
* Commercial CD and modern masters: −9 LUFS
* Film and broadcast: −24 LUFS
L/R Bars
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Visual peak meters for the left and right channels, including a white hold marker that indicates the highest recent peak.
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PHASE (Goniometer)
Displays stereo correlation.
A vertical cloud generally indicates good mono compatibility.
A horizontal cloud suggests phase issues that may cause cancellation when summed to mono.
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Frequency Band Visualization
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The analyzer divides the frequency spectrum into seven bands, each represented by a color that gradually transitions from white (sub-bass frequencies) to deep red (high frequencies):
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SUB (20–60 Hz) — White
BASS (60–250 Hz) — Very light pink
LO (250–500 Hz) — Light pink
MID (500 Hz–2 kHz) — Coral
HI-M (2–6 kHz) — Light red
HI (6–12 kHz) — Red
AIR (12–20 kHz) — Deep red
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The rings, spectral arc, and particles inherit these colors, allowing you to quickly identify where energy is concentrated within the mix.
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Production Recommendations
For meaningful analysis results, allow the song to play through completely at least once so that the Integrated LUFS and Average RMS values become representative of the entire track.
To reset all measurements, press ā® Restart or reload the file. All accumulators are cleared whenever a new file is loaded.
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Privacy Notice
Audio and video files are processed locally within your browser and are never uploaded to or stored on our servers.
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User Responsibility
Please use only audio files for which you own the rights or have the necessary permissions.
This tool is intended exclusively for educational, creative, and music production analysis purposes.
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Developed by David Sicard Rock and John Castillo.