/**
 * 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.conversion;

import org.openimaj.audio.AudioFormat;
import org.openimaj.audio.AudioStream;
import org.openimaj.audio.SampleChunk;
import org.openimaj.audio.processor.AudioProcessor;
import org.openimaj.audio.samples.SampleBuffer;
import org.openimaj.audio.samples.SampleBufferFactory;

/**
 *      An audio processor that converts the bit-depth of an audio stream.
 *      The algorithm used to provide the conversion is enumerated within
 *      the {@link BitDepthConversionAlgorithm} enum, a public inner class
 *      within this class. The class supports chainable and direct processing,
 *      like all audio processors should.
 *      <p>
 *      To use the class on an audio stream, use something like the following:
 *      <p>
 *      <code><pre>
 *              BitDepthConverter bdc = new BitDepthConverter(
 *                      audioStream,
 *                      BitDepthConversionAlgorithm.NEAREST,
 *                      new AudioFormat( 8, 44.1, 1 ) );
 *      </pre></code>
 *      <p>
 *      The constructors take an output format which must match the audio format
 *      of the incoming stream in all respects other than the bit-depth. If the
 *      input and output formats differ, an {@link IllegalArgumentException} will
 *      be thrown. If the input and output formats are identical in every respect,
 *      the processor does nothing.
 *      <p>
 *      For the NEAREST algorithm, the conversion of the bit-depth is
 *      mainly provided through the {@link SampleBuffer} class.
 *
 *  @author David Dupplaw (dpd@ecs.soton.ac.uk)
 *      @created 18 Jun 2012
 */
public class BitDepthConverter extends AudioProcessor
{
        /**
         *      An enumerator of the different bit-depth conversion algorithms
         *      available.
         *
         *  @author David Dupplaw (dpd@ecs.soton.ac.uk)
         *      @created 18 Jun 2012
         */
        public enum BitDepthConversionAlgorithm
        {
                /**
                 *      Performs a basic nearest value rounding bit-depth conversion. It
                 *      does this by utilising the sample buffer conversion routines.
                 */
                NEAREST
                {
                        @Override
            public SampleChunk process( final SampleChunk s, final AudioFormat output )
            {
                                final SampleBuffer sbin = s.getSampleBuffer();
                                final SampleBuffer sbout = SampleBufferFactory.createSampleBuffer(
                                                output, sbin.size() );
                                sbout.setFormat( output );

                                // The sample buffer will do the conversion
                                for( int i = 0; i < sbin.size(); i++ )
                                        sbout.set( i, sbin.get(i) );

                                return sbout.getSampleChunk();
            }
                };

                /**
                 *      Process a sample chunk and output a sample chunk in the given
                 *      output format.
                 *
                 *  @param s The input sample chunk
                 *  @param output The output format
                 *  @return A resampled sample chunk.
                 */
                public abstract SampleChunk process( SampleChunk s, AudioFormat output );
        }

        /**
         * Bit depth conversion defaults to
         * {@link BitDepthConversionAlgorithm#NEAREST}
         */
        private BitDepthConversionAlgorithm bitDepthConverter =
                BitDepthConversionAlgorithm.NEAREST;

        /** The output format to which sample chunks will be converted */
        private AudioFormat outputFormat = null;

        /**
         *      Default constructor that takes the input conversion
         *  @param converter The converter to use
         *  @param outputFormat The output format to convert to
         */
        public BitDepthConverter( final BitDepthConversionAlgorithm converter,
                        final AudioFormat outputFormat )
    {
                this.bitDepthConverter = converter;
                this.outputFormat = outputFormat;
                this.setFormat( outputFormat );
    }

        /**
         *      Chainable constructor.
         *
         *  @param as The audio stream to process
         *  @param converter The converter to use
         *  @param outputFormat The output format to convert to
         */
        public BitDepthConverter( final AudioStream as, final BitDepthConversionAlgorithm converter,
                        final AudioFormat outputFormat )
        {
                super( as );
                this.bitDepthConverter = converter;
                this.outputFormat = outputFormat;
                this.setFormat( outputFormat );
        }

        /**
         *      {@inheritDoc}
         *      @see org.openimaj.audio.processor.AudioProcessor#process(org.openimaj.audio.SampleChunk)
         */
        @Override
        public SampleChunk process( final SampleChunk sample ) throws Exception
        {
                if( sample.getFormat().getSampleRateKHz() != this.outputFormat.getSampleRateKHz() )
                        throw new IllegalArgumentException( "The sample rate of the " +
                                        "output format is not the same as the sample chunk. Use a " +
                                        "sample rate converter first before using the bit depth" +
                                        "converter." );

                if( sample.getFormat().getNumChannels() != this.outputFormat.getNumChannels() )
                        throw new IllegalArgumentException( "The number of channels in the " +
                                        "output format is not the same as the sample chunk. Use a " +
                                        "channel converter first before using the bit-depth " +
                                        "converter." );

                if( sample.getFormat().getNBits() == this.outputFormat.getNBits() )
                        return sample;

                final SampleChunk sc = this.bitDepthConverter.process( sample, this.outputFormat );
                sc.setStartTimecode( sample.getStartTimecode() );
                return sc;
        }
}