formatproximitycomparator.java

FMJ（freedom media for java)是java视频开发的新选择

package net.sf.fmj.filtergraph;

import java.util.Comparator;

import javax.media.Format;
import javax.media.format.AudioFormat;

import net.sf.fmj.utility.FormatUtils;

import com.lti.utils.ObjUtils;

/**
 * 
 * Compares formats to a target format.  Used to improve search order in building filter graph, when a target format is known.
 * @author Ken Larson
 *
 */
public class FormatProximityComparator implements Comparator
{
	private final Format target;
	
	public FormatProximityComparator(final Format target)
	{
		super();
		this.target = target;
	}

	public int compare(Object a, Object b)
	{
		if (a == null && b == null)
			return 0;
		if (a == null)	// then a < b, return -1
			return -1;
		if (b == null)
			return 1;	// a > b
		
		final Format aCast = (Format) a;
		final Format bCast = (Format) b;
			
		// similarity is higher for better matches, but we need lower values to sort right, so we multiply by -1.
		return -1 * (similarity(aCast, target) - similarity(bCast, target)) ;
	}
	
	private static final int EQUALS 			= 0x80000000;
	private static final int MATCHES 			= 0x40000000;
	private static final int SAME_CLASS 		= 0x20000000;
	private static final int ASSIGNABLE 		= 0x10000000;
	private static final int ENCODINGS_EQUAL 	= 0x08000000;
	private static final int DATA_TYPES_EQUAL 	= 0x04000000;
	
	private static int similarity(Format a, Format b)
	{
		if (a.equals(b))
			return EQUALS;
		
		int n = 0;
		
		if (a.matches(b))
			n += MATCHES;

		if (a.getClass() == b.getClass())
			n += SAME_CLASS;

		if (a.getClass().isAssignableFrom(b.getClass()) ||
			b.getClass().isAssignableFrom(a.getClass()))
			n += ASSIGNABLE;
	
		if (ObjUtils.equal(a.getEncoding(), b.getEncoding()))
			n += ENCODINGS_EQUAL;

		if (ObjUtils.equal(a.getDataType(), b.getDataType()))
			n += DATA_TYPES_EQUAL;

		if (a instanceof AudioFormat && b instanceof AudioFormat)
			n += audioFormatSimilarity((AudioFormat) a, (AudioFormat) b);
		
		// TODO: video format similarity
		
		return n;
		
	}
	
	
	
	private static int similarity(int a, int b, int equalsValue, int matchesValue)
	{
		int n = 0;
		if (a == b)
			n += equalsValue;
		if (FormatUtils.matches(a, b))
			n += matchesValue;
		return n;
	}
	
	private static int similarity(float a, float b, int equalsValue, int matchesValue)
	{
		int n = 0;
		if (a == b)
			n += equalsValue;
		if (FormatUtils.matches(a, b))
			n += matchesValue;
		return n;
	}
	
	private static int similarity(double a, double b, int equalsValue, int matchesValue)
	{
		int n = 0;
		if (a == b)
			n += equalsValue;
		if (FormatUtils.matches(a, b))
			n += matchesValue;
		return n;
	}
	
	
	// all attributes have equal ranking
	private static int SAMPLE_RATE_EQUAL				= 0x00800000;
	private static int SAMPLE_RATE_MATCHES				= 0x00400000;
	private static int SAMPLE_SIZE_IN_BITS_EQUAL		= 0x00800000;
	private static int SAMPLE_SIZE_IN_BITS_MATCHES		= 0x00400000;
	private static int CHANNELS_EQUAL					= 0x00800000;
	private static int CHANNELS_MATCHES					= 0x00400000;
	private static int ENDIAN_EQUAL						= 0x00800000;
	private static int ENDIAN_MATCHES					= 0x00400000;
	private static int SIGNED_EQUAL						= 0x00800000;
	private static int SIGNED_MATCHES					= 0x00400000;
	private static int FRAME_SIZE_IN_BITS_EQUAL			= 0x00800000;
	private static int FRAME_SIZE_IN_BITS_MATCHES		= 0x00400000;
	private static int FRAME_RATE_EQUAL					= 0x00800000;
	private static int FRAME_RATE_MATCHES				= 0x00400000;

	private static int audioFormatSimilarity(AudioFormat a, AudioFormat b)
	{
		int n = 0;
		n += similarity(a.getSampleRate(), b.getSampleRate(), SAMPLE_RATE_EQUAL, SAMPLE_RATE_MATCHES);
		n += similarity(a.getSampleSizeInBits(), b.getSampleSizeInBits(), SAMPLE_SIZE_IN_BITS_EQUAL, SAMPLE_SIZE_IN_BITS_MATCHES);
		n += similarity(a.getChannels(), b.getChannels(), CHANNELS_EQUAL, CHANNELS_MATCHES);
		n += similarity(a.getEndian(), b.getEndian(), ENDIAN_EQUAL, ENDIAN_MATCHES);
		n += similarity(a.getSigned(), b.getSigned(), SIGNED_EQUAL, SIGNED_MATCHES);
		n += similarity(a.getFrameSizeInBits(), b.getFrameSizeInBits(), FRAME_SIZE_IN_BITS_EQUAL, FRAME_SIZE_IN_BITS_MATCHES);
		n += similarity(a.getFrameRate(), b.getFrameRate(), FRAME_RATE_EQUAL, FRAME_RATE_MATCHES);
		return n;



		
		
	}
	
}