auto import from //branches/cupcake/...@126645
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The Android Open Source Project
267
core/java/android/speech/srec/WaveHeader.java
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267
core/java/android/speech/srec/WaveHeader.java
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/*
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* Copyright (C) 2009 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.speech.srec;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.OutputStream;
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/**
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* This class represents the header of a WAVE format audio file, which usually
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* have a .wav suffix. The following integer valued fields are contained:
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* <ul>
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* <li> format - usually PCM, ALAW or ULAW.
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* <li> numChannels - 1 for mono, 2 for stereo.
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* <li> sampleRate - usually 8000, 11025, 16000, 22050, or 44100 hz.
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* <li> bitsPerSample - usually 16 for PCM, 8 for ALAW, or 8 for ULAW.
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* <li> numBytes - size of audio data after this header, in bytes.
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* </ul>
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* @hide pending API council approval
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*/
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public class WaveHeader {
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// follows WAVE format in http://ccrma.stanford.edu/courses/422/projects/WaveFormat
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private static final String TAG = "WaveHeader";
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private static final int HEADER_LENGTH = 44;
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/** Indicates PCM format. */
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public static final short FORMAT_PCM = 1;
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/** Indicates ALAW format. */
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public static final short FORMAT_ALAW = 6;
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/** Indicates ULAW format. */
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public static final short FORMAT_ULAW = 7;
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private short mFormat;
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private short mNumChannels;
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private int mSampleRate;
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private short mBitsPerSample;
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private int mNumBytes;
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/**
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* Construct a WaveHeader, with all fields defaulting to zero.
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*/
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public WaveHeader() {
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}
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/**
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* Construct a WaveHeader, with fields initialized.
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* @param format format of audio data,
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* one of {@link #FORMAT_PCM}, {@link #FORMAT_ULAW}, or {@link #FORMAT_ALAW}.
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* @param numChannels 1 for mono, 2 for stereo.
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* @param sampleRate typically 8000, 11025, 16000, 22050, or 44100 hz.
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* @param bitsPerSample usually 16 for PCM, 8 for ULAW or 8 for ALAW.
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* @param numBytes size of audio data after this header, in bytes.
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*/
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public WaveHeader(short format, short numChannels, int sampleRate, short bitsPerSample, int numBytes) {
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mFormat = format;
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mSampleRate = sampleRate;
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mNumChannels = numChannels;
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mBitsPerSample = bitsPerSample;
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mNumBytes = numBytes;
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}
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/**
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* Get the format field.
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* @return format field,
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* one of {@link #FORMAT_PCM}, {@link #FORMAT_ULAW}, or {@link #FORMAT_ALAW}.
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*/
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public short getFormat() {
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return mFormat;
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}
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/**
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* Set the format field.
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* @param format
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* one of {@link #FORMAT_PCM}, {@link #FORMAT_ULAW}, or {@link #FORMAT_ALAW}.
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* @return reference to this WaveHeader instance.
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*/
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public WaveHeader setFormat(short format) {
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mFormat = format;
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return this;
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}
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/**
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* Get the number of channels.
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* @return number of channels, 1 for mono, 2 for stereo.
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*/
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public short getNumChannels() {
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return mNumChannels;
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}
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/**
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* Set the number of channels.
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* @param numChannels 1 for mono, 2 for stereo.
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* @return reference to this WaveHeader instance.
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*/
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public WaveHeader setNumChannels(short numChannels) {
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mNumChannels = numChannels;
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return this;
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}
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/**
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* Get the sample rate.
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* @return sample rate, typically 8000, 11025, 16000, 22050, or 44100 hz.
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*/
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public int getSampleRate() {
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return mSampleRate;
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}
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/**
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* Set the sample rate.
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* @param sampleRate sample rate, typically 8000, 11025, 16000, 22050, or 44100 hz.
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* @return reference to this WaveHeader instance.
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*/
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public WaveHeader setSampleRate(int sampleRate) {
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mSampleRate = sampleRate;
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return this;
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}
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/**
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* Get the number of bits per sample.
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* @return number of bits per sample,
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* usually 16 for PCM, 8 for ULAW or 8 for ALAW.
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*/
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public short getBitsPerSample() {
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return mBitsPerSample;
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}
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/**
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* Set the number of bits per sample.
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* @param bitsPerSample number of bits per sample,
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* usually 16 for PCM, 8 for ULAW or 8 for ALAW.
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* @return reference to this WaveHeader instance.
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*/
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public WaveHeader setBitsPerSample(short bitsPerSample) {
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mBitsPerSample = bitsPerSample;
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return this;
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}
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/**
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* Get the size of audio data after this header, in bytes.
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* @return size of audio data after this header, in bytes.
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*/
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public int getNumBytes() {
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return mNumBytes;
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}
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/**
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* Set the size of audio data after this header, in bytes.
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* @param numBytes size of audio data after this header, in bytes.
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* @return reference to this WaveHeader instance.
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*/
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public WaveHeader setNumBytes(int numBytes) {
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mNumBytes = numBytes;
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return this;
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}
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/**
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* Read and initialize a WaveHeader.
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* @param in {@link java.io.InputStream} to read from.
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* @return number of bytes consumed.
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* @throws IOException
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*/
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public int read(InputStream in) throws IOException {
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/* RIFF header */
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readId(in, "RIFF");
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int numBytes = readInt(in) - 36;
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readId(in, "WAVE");
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/* fmt chunk */
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readId(in, "fmt ");
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if (16 != readInt(in)) throw new IOException("fmt chunk length not 16");
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mFormat = readShort(in);
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mNumChannels = readShort(in);
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mSampleRate = readInt(in);
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int byteRate = readInt(in);
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short blockAlign = readShort(in);
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mBitsPerSample = readShort(in);
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if (byteRate != mNumChannels * mSampleRate * mBitsPerSample / 8) {
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throw new IOException("fmt.ByteRate field inconsistent");
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}
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if (blockAlign != mNumChannels * mBitsPerSample / 8) {
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throw new IOException("fmt.BlockAlign field inconsistent");
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}
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/* data chunk */
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readId(in, "data");
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mNumBytes = readInt(in);
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return HEADER_LENGTH;
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}
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private static void readId(InputStream in, String id) throws IOException {
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for (int i = 0; i < id.length(); i++) {
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if (id.charAt(i) != in.read()) throw new IOException( id + " tag not present");
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}
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}
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private static int readInt(InputStream in) throws IOException {
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return in.read() | (in.read() << 8) | (in.read() << 16) | (in.read() << 24);
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}
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private static short readShort(InputStream in) throws IOException {
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return (short)(in.read() | (in.read() << 8));
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}
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/**
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* Write a WAVE file header.
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* @param out {@link java.io.OutputStream} to receive the header.
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* @return number of bytes written.
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* @throws IOException
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*/
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public int write(OutputStream out) throws IOException {
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/* RIFF header */
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writeId(out, "RIFF");
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writeInt(out, 36 + mNumBytes);
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writeId(out, "WAVE");
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/* fmt chunk */
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writeId(out, "fmt ");
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writeInt(out, 16);
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writeShort(out, mFormat);
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writeShort(out, mNumChannels);
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writeInt(out, mSampleRate);
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writeInt(out, mNumChannels * mSampleRate * mBitsPerSample / 8);
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writeShort(out, (short)(mNumChannels * mBitsPerSample / 8));
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writeShort(out, mBitsPerSample);
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/* data chunk */
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writeId(out, "data");
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writeInt(out, mNumBytes);
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return HEADER_LENGTH;
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}
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private static void writeId(OutputStream out, String id) throws IOException {
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for (int i = 0; i < id.length(); i++) out.write(id.charAt(i));
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}
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private static void writeInt(OutputStream out, int val) throws IOException {
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out.write(val >> 0);
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out.write(val >> 8);
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out.write(val >> 16);
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out.write(val >> 24);
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}
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private static void writeShort(OutputStream out, short val) throws IOException {
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out.write(val >> 0);
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out.write(val >> 8);
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}
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}
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