mulawencoderdecodertest.java

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

package net.sf.fmj.media.codec.audio.ulaw;

import net.sf.fmj.utility.UnsignedUtils;
import junit.framework.TestCase;

/**
 * 
 * @author Ken Larson
 *
 */
public class MuLawEncoderDecoderTest extends TestCase 
{

	// from http://en.wikipedia.org/wiki/%CE%9C-law_algorithm
	   private static final int[] ULAW_TO_LINEAR_16_BIT = new int[]{
           -32124, -31100, -30076, -29052, -28028, -27004, -25980, -24956, -23932, -22908, -21884, -20860, -19836, -18812,
           -17788, -16764, -15996, -15484, -14972, -14460, -13948, -13436, -12924, -12412, -11900, -11388, -10876, -10364,
           -9852, -9340, -8828, -8316, -7932, -7676, -7420, -7164, -6908, -6652, -6396, -6140, -5884, -5628, -5372, -5116,
           -4860, -4604, -4348, -4092, -3900, -3772, -3644, -3516, -3388, -3260, -3132, -3004, -2876, -2748, -2620, -2492,
           -2364, -2236, -2108, -1980, -1884, -1820, -1756, -1692, -1628, -1564, -1500, -1436, -1372, -1308, -1244, -1180,
           -1116, -1052, -988, -924, -876, -844, -812, -780, -748, -716, -684, -652, -620, -588, -556, -524, -492, -460,
           -428, -396, -372, -356, -340, -324, -308, -292, -276, -260, -244, -228, -212, -196, -180, -164, -148, -132, -120,
           -112, -104, -96, -88, -80, -72, -64, -56, -48, -40, -32, -24, -16, -8, 0, 32124, 31100, 30076, 29052, 28028,
           27004, 25980, 24956, 23932, 22908, 21884, 20860, 19836, 18812, 17788, 16764, 15996, 15484, 14972, 14460, 13948,
           13436, 12924, 12412, 11900, 11388, 10876, 10364, 9852, 9340, 8828, 8316, 7932, 7676, 7420, 7164, 6908, 6652, 6396,
           6140, 5884, 5628, 5372, 5116, 4860, 4604, 4348, 4092, 3900, 3772, 3644, 3516, 3388, 3260, 3132, 3004, 2876, 2748,
           2620, 2492, 2364, 2236, 2108, 1980, 1884, 1820, 1756, 1692, 1628, 1564, 1500, 1436, 1372, 1308, 1244, 1180, 1116,
           1052, 988, 924, 876, 844, 812, 780, 748, 716, 684, 652, 620, 588, 556, 524, 492, 460, 428, 396, 372, 356, 340,
           324, 308, 292, 276, 260, 244, 228, 212, 196, 180, 164, 148, 132, 120, 112, 104, 96, 88, 80, 72, 64, 56, 48, 40,
           32, 24, 16, 8, 0};
	   
	
	public void testTableLookup()
	{
		for (int i = 0; i <= 255; ++i)
		{
			byte b = (byte) i;
			short s = MuLawDecoderUtil.muLawDecode(b);
			short sLookup = (short) ULAW_TO_LINEAR_16_BIT[UnsignedUtils.uByteToInt(b)];
			assertEquals(s, sLookup);
				
		}
		
	}
	
	public void testShorts()
	{
		for (int i = Short.MIN_VALUE; i <= Short.MAX_VALUE; ++i)
		{
			short s = (short) i;
			byte bEncoded = MuLawEncoderUtil.muLawEncode(s);
			
			for (int j = 0; j < ULAW_TO_LINEAR_16_BIT.length - 1; ++j)
			{
				if (s < 0)
				{
					if (s > ULAW_TO_LINEAR_16_BIT[j] && s < ULAW_TO_LINEAR_16_BIT[j + 1])
					{
						final boolean eq0 = bEncoded == (byte) j;
						final boolean eq1 = bEncoded == (byte) (j + 1);
						if (!eq0 && !eq1)
							System.err.println("s=" + s + " j=" + j + " bEncoded=" + bEncoded + " ULAW_TO_LINEAR_16_BIT[j]=" + ULAW_TO_LINEAR_16_BIT[j] + " ULAW_TO_LINEAR_16_BIT[j + 1]=" + ULAW_TO_LINEAR_16_BIT[j + 1]);
						assertTrue(eq0 || eq1);
					}
				}
				else if (s > 0)
				{
					if (s < ULAW_TO_LINEAR_16_BIT[j] && s > ULAW_TO_LINEAR_16_BIT[j + 1])
					{
						final boolean eq0 = bEncoded == (byte) j;
						final boolean eq1 = bEncoded == (byte) (j + 1);
						if (!eq0 && !eq1)
							System.err.println("s=" + s + " j=" + j + " bEncoded=" + bEncoded + " ULAW_TO_LINEAR_16_BIT[j]=" + ULAW_TO_LINEAR_16_BIT[j] + " ULAW_TO_LINEAR_16_BIT[j + 1]=" + ULAW_TO_LINEAR_16_BIT[j + 1]);
						assertTrue(eq0 || eq1);
					}
				}
			}
		}
	}

	public void testTable()
	{
		for (int i = 0; i <= 255; ++i)
		{
			byte b = (byte) i;
			test(b);
		}
	}

	private void test(byte b)
	{
		short s = MuLawDecoderUtil.muLawDecode(b);
		byte bEncoded = MuLawEncoderUtil.muLawEncode(s);
		//if (b != bEncoded)
		//	System.err.println("b != bEncoded " + b + "  " + bEncoded + " s=" + s);
		if (b == 127)
		{	assertEquals(bEncoded, -1);	// there are 2 values that can yield the same short value of 0 - -1 and 127.
			assertEquals(s, 0);
		}
		else	
			assertEquals(b, bEncoded);
	}
}