1 /**
2 * Copyright (c) 2011, The University of Southampton and the individual contributors.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without modification,
6 * are permitted provided that the following conditions are met:
7 *
8 * * Redistributions of source code must retain the above copyright notice,
9 * this list of conditions and the following disclaimer.
10 *
11 * * Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * * Neither the name of the University of Southampton nor the names of its
16 * contributors may be used to endorse or promote products derived from this
17 * software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
21 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
22 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
23 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
24 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
26 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30 /**
31 *
32 */
33 package org.openimaj.audio.analysis;
34
35 import org.openimaj.audio.SampleChunk;
36 import org.openimaj.audio.filters.VolumeAdjustProcessor;
37 import org.openimaj.audio.processor.AudioProcessor;
38 import org.openimaj.audio.samples.SampleBuffer;
39
40 /**
41 * Calculates the scalar necessary to achieve peak value of the loudest part of
42 * the given input signal. This scalar can be retrieved using the
43 * {@link #getVolumeScalar()} method which will return the scalar as it has
44 * currently been calculated for the stream which has passed. This will only
45 * return the correct value for the whole audio stream once the whole audio
46 * stream has passed through the processor. This processor will not perform
47 * attenuation - that is, the volume scalar will always be greater than 1 (and
48 * positive).
49 * <p>
50 * The value of the peak volume scalar is compatible with the
51 * {@link VolumeAdjustProcessor} which can adjust the volume to the maximum peak
52 * value.
53 *
54 * @author David Dupplaw (dpd@ecs.soton.ac.uk)
55 * @created 10 Dec 2012
56 * @version $Author$, $Revision$, $Date$
57 */
58 public class PeakNormalisationCalculator extends AudioProcessor
59 {
60 /** The peak scalar as it's been calcultated so far in the stream */
61 private float scalar = Float.MAX_VALUE;
62
63 /**
64 * {@inheritDoc}
65 *
66 * @see org.openimaj.audio.processor.AudioProcessor#process(org.openimaj.audio.SampleChunk)
67 */
68 @Override
69 public SampleChunk process(final SampleChunk sample) throws Exception
70 {
71 // This allows us to retrieve samples that are scaled to 0..1 float
72 // values
73 final SampleBuffer sb = sample.getSampleBuffer();
74
75 for (final float s : sb)
76 if (Math.abs(s) * this.scalar > 1)
77 this.scalar = 1 / Math.abs(s);
78
79 return sample;
80 }
81
82 /**
83 * Returns the calculated peak scalar as it currently stands in the stream.
84 * If no audio has passed through the processor, this will return
85 * {@link Float#MAX_VALUE} otherwise the value will always be positive and
86 * greater than 1.
87 *
88 * @return The calculated peak scalar.
89 */
90 public float getVolumeScalar()
91 {
92 return this.scalar;
93 }
94 }