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Commit a1f0113d authored by Mikhail Naganov's avatar Mikhail Naganov
Browse files

Visualizer: update docs for the RMS measurements 

Indicate that the effect can return >0 dBFS RMS reading
when used on the global session. Update the expected
minimum value.

Bug: 202015438
Test: m
Change-Id: Ied49b690eebfca8cd98ebfbc529a014e9321c811
parent 91adf12e

media/java/android/media/audiofx/Visualizer.java

+12 −4
Original line number Diff line number Diff line
@@ -110,10 +110,18 @@ public class Visualizer { 
    public static final int MEASUREMENT_MODE_NONE = 0;



    /**

     * Defines a measurement mode which computes the peak and RMS value in mB, where 0mB is the

     * maximum sample value, and -9600mB is the minimum value.

     * Values for peak and RMS can be retrieved with

     * {@link #getMeasurementPeakRms(MeasurementPeakRms)}.

     * Defines a measurement mode which computes the peak and RMS value in mB below the

     * "full scale", where 0mB is normally the maximum sample value (but see the note

     * below). Minimum value depends on the resolution of audio samples used by the audio

     * framework. The value of -9600mB is the minimum value for 16-bit audio systems and

     * -14400mB or below for "high resolution" systems. Values for peak and RMS can be

     * retrieved with {@link #getMeasurementPeakRms(MeasurementPeakRms)}.

     *

     * <p class=note><strong>Note:</strong> when Visualizer effect is attached to the

     * global session (with session ID 0), it is possible to observe RMS peaks higher than

     * 0 dBFS, for example in the case when there are multiple audio sources playing

     * simultaneously. In this case {@link #getMeasurementPeakRms(MeasurementPeakRms)}

     * method can return a positive value.

     */

    public static final int MEASUREMENT_MODE_PEAK_RMS = 1 << 0;