Aura Help Center

Needle

The Needle meter uses an arcing pointer to indicate a signal level

Three different kinds of scales are available: VU and BBC for “volume”, and LU for program loudness. Defaults are set to industry standards, but the indicators are fully configurable. The meter also includes LED-like indicators for peaks and values beyond the scale range.

Controls

Hover the mouse over the meter to reveal the control bar.
Show the meter configuration popover
Show the indicators configuration popover
Pause the meter
Run the meter
Reset the meter values

Meter Configuration

  1. The meter’s mode
    • VU: Classic “volume unit” scale, with primary and secondary indicators
    • BBC: British Broadcasting Company scale, with primary and secondary indicators
    • LU +9: Standard program loudness scale from -18 LU to +9 LU
    • LU +18: Standard program loudness scale from -36 LU to +18 LU
  2. The background color
  3. The unscaled value that will appear at 0 on the scaled meter.

Primary Indicator — Magnitude

The primary indicator is one of two arcing pointers on the meter. When the meter is in VU or BBC metering mode, this is the panel used for configuring the primary indicator.
  1. The audio inputs to combine.
  2. The method used to combine the channels.
    • Sum: adds the samples together
    • Difference: even numbered channels are subtracted from odd numbered channels
    • Average: the samples are added together and divided by the number of channels
    • Average Difference: even numbered channels are subtracted from odd numbered channels and the result is divided by the number of channels
  3. The amount of gain to be added to the combined result.
  4. The mathematical algorithm to use to quantify the set of audio samples.
    • Peak: The maximum magnitude
    • TruePeak: The maximum magnitude after a high-definition upsampling
    • RMS: The root-mean-square
    • AES-17: The root-mean-square value + 3dB
    • Average: The mean
  5. Select the response rise and fall times.
  6.   Rise Time Hold Time Fall Time
    Digital 9.5dB in 1.7ms none 20dB in 850ms
    PPM Type I 9.5dB in 1.7ms none 20dB in 1.7s
    PPM Type II 9.5dB in 1.7ms 100ms 24dB in 2.8s
    VU 40dB in 300ms none 40dB in 300ms
    Nordic 14dB in 5ms none 20dB in 1.5s
    BBC/EBU 14dB in 5ms none 24dB in 2.85s
    Peak Hold (Short) immediate 0.7s 60dB in 300ms
    Peak Hold (Long) immediate 2.0s 60dB in 300ms
    Peak Hold (Infinite) immediate forever none
  7. The indicator color
  8. Select to run the trace. Deselect to pause.
  9. Select to hide the trace.
  10. Select to show LED-like arrows above the arc that identify when the value is above the scale.
  11. Select to show LED-like arrows below the arc that identify when the value is below the scale.

Primary Indicator — Loudness

The primary indicator is one of two arcing pointers on the meter. When the meter is one of the LU metering modes, this is the panel used for configuring the primary indicator.
  1. The audio input that contains the left channel content.
  2. The audio input that contains the right channel content.
  3. The audio input that contains the center channel content.
  4. The audio input that contains the left surround channel content.
  5. The audio input that contains the right surround channel content.
  6. The time scale for the program loudness measurement
    • Momentary: a non-gated time window of 0.4s
    • Short-Term: a non-gated time window of 3.0s
    • Integrated: the gated accumulated value
  7. The indicator color
  8. Select to run the trace. Deselect to pause.
  9. Select to hide the trace.

Secondary Indicator

The secondary indicator is one of two arcing pointers on the meter.
  1. The audio inputs to combine.
  2. The method used to combine the channels.
    • Sum: adds the samples together
    • Difference: even numbered channels are subtracted from odd numbered channels
    • Average: the samples are added together and divided by the number of channels
    • Average Difference: even numbered channels are subtracted from odd numbered channels and the result is divided by the number of channels
  3. The amount of gain to be added to the combined result.
  4. The mathematical algorithm to use to quantify the set of audio samples.
    • Peak: The maximum magnitude
    • TruePeak: The maximum magnitude after a high-definition upsampling
    • RMS: The root-mean-square
    • AES-17: The root-mean-square value + 3dB
    • Average: The mean
  5. Select the response rise and fall times.
  6.   Rise Time Hold Time Fall Time
    Digital 9.5dB in 1.7ms none 20dB in 850ms
    PPM Type I 9.5dB in 1.7ms none 20dB in 1.7s
    PPM Type II 9.5dB in 1.7ms 100ms 24dB in 2.8s
    VU 40dB in 300ms none 40dB in 300ms
    Nordic 14dB in 5ms none 20dB in 1.5s
    BBC/EBU 14dB in 5ms none 24dB in 2.85s
    Peak Hold (Short) immediate 0.7s 60dB in 300ms
    Peak Hold (Long) immediate 2.0s 60dB in 300ms
    Peak Hold (Infinite) immediate forever none
  7. The indicator color
  8. Select to run the trace. Deselect to pause.
  9. Select to hide the trace.

Peak Light Indicator

The Peak Light is an LED-like indicator in the top-right corner of the meter. It is classically used to identify peaks when the needle indicators are not fast enough to identify them.
  1. The audio inputs to combine.
  2. The method used to combine the channels.
    • Sum: adds the samples together
    • Difference: even numbered channels are subtracted from odd numbered channels
    • Average: the samples are added together and divided by the number of channels
    • Average Difference: even numbered channels are subtracted from odd numbered channels and the result is divided by the number of channels
  3. The amount of gain to be added to the combined result.
  4. The mathematical algorithm to use to quantify the set of audio samples.
    • Peak: The maximum magnitude
    • TruePeak: The maximum magnitude after a high-definition upsampling
  5. Select the response rise and fall times.
  6.   Rise Time Hold Time Fall Time
    Digital immediate none 20dB in 850ms
    Analog * 40dB in 300ms none 40dB in 300ms
    Hold (Short) immediate 0.7s none
    Hold (Long) immediate 2.0s none
    Hold (Infinite) immediate forever none
    * The analog response will begin to light the indicator within -6dB of the threshold.
  7. The indicator color
  8. Select to run the trace. Deselect to pause.
  9. Select to hide the trace.