org.openimaj.audio.analysis.PeakNormalisationCalculator Maven / Gradle / Ivy
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/**
* Copyright (c) 2011, The University of Southampton and the individual contributors.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of the University of Southampton nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
*
*/
package org.openimaj.audio.analysis;
import org.openimaj.audio.SampleChunk;
import org.openimaj.audio.filters.VolumeAdjustProcessor;
import org.openimaj.audio.processor.AudioProcessor;
import org.openimaj.audio.samples.SampleBuffer;
/**
* Calculates the scalar necessary to achieve peak value of the loudest part of
* the given input signal. This scalar can be retrieved using the
* {@link #getVolumeScalar()} method which will return the scalar as it has
* currently been calculated for the stream which has passed. This will only
* return the correct value for the whole audio stream once the whole audio
* stream has passed through the processor. This processor will not perform
* attenuation - that is, the volume scalar will always be greater than 1 (and
* positive).
*
* The value of the peak volume scalar is compatible with the
* {@link VolumeAdjustProcessor} which can adjust the volume to the maximum peak
* value.
*
* @author David Dupplaw ([email protected])
* @created 10 Dec 2012
* @version $Author$, $Revision$, $Date$
*/
public class PeakNormalisationCalculator extends AudioProcessor
{
/** The peak scalar as it's been calcultated so far in the stream */
private float scalar = Float.MAX_VALUE;
/**
* {@inheritDoc}
*
* @see org.openimaj.audio.processor.AudioProcessor#process(org.openimaj.audio.SampleChunk)
*/
@Override
public SampleChunk process(final SampleChunk sample) throws Exception
{
// This allows us to retrieve samples that are scaled to 0..1 float
// values
final SampleBuffer sb = sample.getSampleBuffer();
for (final float s : sb)
if (Math.abs(s) * this.scalar > 1)
this.scalar = 1 / Math.abs(s);
return sample;
}
/**
* Returns the calculated peak scalar as it currently stands in the stream.
* If no audio has passed through the processor, this will return
* {@link Float#MAX_VALUE} otherwise the value will always be positive and
* greater than 1.
*
* @return The calculated peak scalar.
*/
public float getVolumeScalar()
{
return this.scalar;
}
}