Meters, Peaks, and Clipping

Documentation / Contents - Audio Panel

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Meters, Peaks, and Clipping

The LED columns beside the input faders are level meters. They show the SIGNAL arriving from the device. They do not show the fader position.

Turning Them On

Tick Meter on an input strip. That starts a separate capture process which samples the device and reports peaks to the panel several times a second. Unticking Meter stops that process. Closing the window stops all of them.

Metering is off by default, because it means opening the record device.

The dB Ladder

Between the two input meters is the scale the meters are read against. It is in decibels relative to full scale, not the 0 to 10 decade the faders use.

C     the converter ran out of numbers
0     full scale, near enough
-2
-4
-7
-10
-20
-30
-40
-50
-60

The top segment, C, lights only when the signal actually reaches full scale. That is the only useful reading of a clip indicator: it means the converter clipped, not that the signal was merely loud.

Aim for peaks around -10 to -4 with the loudest passages touching -2. If C lights, pull the input fader down.

How They Move

The meters rise instantly, hold the peak for about half a second, then fall away smoothly. A full column empties in under two seconds.

If nothing arrives for about a second the LEDs go dark rather than freezing at the last value, so a dark meter means no signal, not a stuck panel.

When There Is No Signal

The meters NEVER show gain in place of a peak. If there is no peak source the panel leaves the LEDs unlit and says so once, rather than faking movement. This is worth knowing, because a mixer that animates its meters from the fader position tells you nothing at all.

Messages the capture process can send to the message line:

no peaks: <device> is busy (another program holds the record device)
no peaks: <device>: permission denied (audio group?)
no peaks: the record device stopped delivering frames
<device> capture gain is 0 -- raise the input fader or the meters stay dark
<device> had no record port selected; chose the microphone

If everything is running and the meters still show nothing, the panel eventually reports digital silence and tells you where to look on your system.

The canonical face is different and says so. Where the backend exposes no peak, its meters fall back to showing the input GAIN, warning once that this is what they are doing. The advanced face never does this.

Checking the Meter Path Without a Window

cymix --peak-probe

runs the capture process headless for five seconds on the default input, prints the live peaks and what the LEDs would show, then sweeps the input fader to report whether the level follows it. The fader ends where it started. Give it a device id to probe a different one.

Meters, Peaks, and Clipping

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