fi.helsinki.cs.ohtu.mpeg2.audio.mpa
Class QuantizationTables

java.lang.Object
  fi.helsinki.cs.ohtu.mpeg2.audio.mpa.QuantizationTables

public class QuantizationTables
extends java.lang.Object

Contains the tables used to quantize MPEG-1 Layer II audio samples.

Nested Class Summary

private static class	QuantizationTables.QLevel Represents a quantization level.
static class	QuantizationTables.QuantizationTable Represents a quantization table for MPEG-1 Layer II audio.

Field Summary

private static QuantizationTables.QLevel[]	q This array contains the 'absolute' quantization levels.
private static java.util.HashMap<java.lang.Integer,QuantizationTables.QuantizationTable>	qTables
private static byte[][]	QUANTIZATION_TABLES Quantization tables suggested by 11172-3 (tables 3-B.2[a-d]).
private static int	SBLIMIT The number of sub-bands

Constructor Summary

private

QuantizationTables()

Method Summary

static QuantizationTables.QuantizationTable	getTable(int table) Returns a quantization table by number.
static QuantizationTables.QuantizationTable	getTable(int sampleRate, int bitratePerChannel) Returns a quantization table suitable for given sample and bitrates.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SBLIMIT

private static final int SBLIMIT

The number of sub-bands

See Also:

Constant Field Values

q

private static final QuantizationTables.QLevel[] q

This array contains the 'absolute' quantization levels. The bit allocation and quantization code use levels relative to sub-band number. With the help of the sub-band number and a quantization table, the relative level is mapped to one of these absolute levels.

QUANTIZATION_TABLES

private static final byte[][] QUANTIZATION_TABLES

Quantization tables suggested by 11172-3 (tables 3-B.2[a-d]). There are four tables which are suitable for different sample and bit rates. For how to read a table, see the code of QuantizationTable(int).

qTables

private static final java.util.HashMap<java.lang.Integer,QuantizationTables.QuantizationTable> qTables

Constructor Detail

QuantizationTables

private QuantizationTables()

Method Detail

getTable

public static QuantizationTables.QuantizationTable getTable(int table)

Returns a quantization table by number. Invoking this method again with the same table number returns the same table instance as before. That is, the following holds always:

     QuantizationTable.getTable(i) == QuantizationTable.getTable(i)
 

getTable

public static QuantizationTables.QuantizationTable getTable(int sampleRate,
                                                            int bitratePerChannel)

Returns a quantization table suitable for given sample and bitrates. Invoking this method again with the same parameters returns the same table instance as before. That is, the following holds always:

     QuantizationTable.getTable(srate, brate) == QuantizationTable.getTable(srate, brate)