MpegStreamTest.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.tika.parser.mp3;
import static java.nio.charset.StandardCharsets.UTF_8;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertNull;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Test;
import org.apache.tika.io.TikaInputStream;
/**
* Test class for {@code MpegStream}.
*/
public class MpegStreamTest {
/**
* The stream to be tested.
*/
private MpegStream stream;
/**
* Writes the given byte the given number of times into an output stream.
*
* @param out the output stream
* @param value the value to write
* @param count the number of bytes to write
* @throws IOException if an error occurs
*/
private static void writeBytes(OutputStream out, int value, int count) throws IOException {
for (int i = 0; i < count; i++) {
out.write(value);
}
}
/**
* Writes a frame header in the given output stream.
*
* @param out the output stream
* @param b2 byte 2 of the header
* @param b3 byte 3 of the header
* @param b4 byte 4 of the header
* @throws IOException if an error occurs
*/
private static void writeFrame(OutputStream out, int b2, int b3, int b4) throws IOException {
out.write(0xFF);
out.write(b2);
out.write(b3);
out.write(b4);
}
@AfterEach
public void tearDown() throws Exception {
if (stream != null) {
stream.close();
}
}
/**
* Tests whether the default test header can be found in a stream.
*
* @param bos the stream
* @throws IOException if an error occurs
*/
private void checkDefaultHeader(ByteArrayOutputStream bos) throws IOException {
TikaInputStream tis = TikaInputStream.get(bos.toByteArray());
stream = new MpegStream(tis);
AudioFrame header = stream.nextFrame();
assertNotNull(header, "No header found");
assertEquals(AudioFrame.MPEG_V2, header.getVersionCode(), "Wrong MPEG version");
assertEquals(AudioFrame.LAYER_3, header.getLayer(), "Wrong layer");
assertEquals(80000, header.getBitRate(), "Wrong bit rate");
assertEquals(24000, header.getSampleRate(), "Wrong sample rate");
}
/**
* Tests whether an audio frame header can be found somewhere in a stream.
*/
@Test
public void testSearchNextFrame() throws IOException {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
writeBytes(bos, 0xFF, 32);
writeBytes(bos, 0, 16);
writeBytes(bos, 0xFF, 8);
bos.write(0xF3);
bos.write(0x96);
bos.write(0);
checkDefaultHeader(bos);
}
/**
* Tests whether invalid frame headers are detected and skipped.
*/
@Test
public void testSearchNextFrameInvalid() throws IOException {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
writeFrame(bos, 0xEB, 0x96, 0);
writeFrame(bos, 0xF9, 0x96, 0);
writeFrame(bos, 0xF3, 0, 0);
writeFrame(bos, 0xF3, 0xF0, 0);
writeFrame(bos, 0xF3, 0x7C, 0);
writeFrame(bos, 0xF3, 0x96, 0);
checkDefaultHeader(bos);
}
/**
* Tests a search for another frame which is interrupted because the stream
* ends.
*/
@Test
public void testSeachNextFrameEOS() throws IOException {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bos.write(0xFF);
bos.write(0xFF);
bos.write(0xF3);
bos.write(0x96);
TikaInputStream tis = TikaInputStream.get(bos.toByteArray());
stream = new MpegStream(tis);
assertNull(stream.nextFrame(), "Got a frame");
}
/**
* Parses a single frame header from the given three header bytes
* following the initial 0xFF sync byte.
*/
private AudioFrame parseHeader(int b2, int b3, int b4) throws IOException {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
writeFrame(bos, b2, b3, b4);
TikaInputStream tis = TikaInputStream.get(bos.toByteArray());
stream = new MpegStream(tis);
AudioFrame header = stream.nextFrame();
assertNotNull(header, "No header found");
return header;
}
/**
* An MPEG1 layer 3 frame carries 1152 samples: 128 kbps at 44100 Hz
* gives 144 * 128000 / 44100 = 417 bytes and 26.12 ms.
*/
@Test
public void testFrameLengthAndDurationMpeg1Layer3() throws IOException {
AudioFrame header = parseHeader(0xFB, 0x90, 0);
assertEquals(AudioFrame.MPEG_V1, header.getVersionCode(), "Wrong MPEG version");
assertEquals(AudioFrame.LAYER_3, header.getLayer(), "Wrong layer");
assertEquals(417, header.getLength(), "Wrong frame length");
assertEquals(1152000f / 44100, header.getDuration(), 0.01f, "Wrong duration");
}
/**
* An MPEG2 layer 3 frame carries only 576 samples (LSF mode), so
* 80 kbps at 24000 Hz with padding gives 72 * 80000 / 24000 + 1 = 241
* bytes and 24 ms, half of what the MPEG1 formula would report.
*/
@Test
public void testFrameLengthAndDurationMpeg2Layer3() throws IOException {
AudioFrame header = parseHeader(0xF3, 0x96, 0);
assertEquals(AudioFrame.MPEG_V2, header.getVersionCode(), "Wrong MPEG version");
assertEquals(AudioFrame.LAYER_3, header.getLayer(), "Wrong layer");
assertEquals(241, header.getLength(), "Wrong frame length");
assertEquals(24.0f, header.getDuration(), 0.01f, "Wrong duration");
}
/**
* MPEG2.5 layer 3 also uses the halved LSF frame: 80 kbps at 12000 Hz
* with padding gives 72 * 80000 / 12000 + 1 = 481 bytes and 48 ms.
*/
@Test
public void testFrameLengthAndDurationMpeg25Layer3() throws IOException {
AudioFrame header = parseHeader(0xE3, 0x96, 0);
assertEquals(AudioFrame.MPEG_V2_5, header.getVersionCode(), "Wrong MPEG version");
assertEquals(AudioFrame.LAYER_3, header.getLayer(), "Wrong layer");
assertEquals(481, header.getLength(), "Wrong frame length");
assertEquals(48.0f, header.getDuration(), 0.01f, "Wrong duration");
}
/**
* Layer 2 keeps 1152 samples in every MPEG version, so the MPEG2 frame
* stays at the full length: 80 kbps at 24000 Hz with padding gives
* 144 * 80000 / 24000 + 1 = 481 bytes and 48 ms.
*/
@Test
public void testFrameLengthAndDurationMpeg2Layer2() throws IOException {
AudioFrame header = parseHeader(0xF5, 0x96, 0);
assertEquals(AudioFrame.MPEG_V2, header.getVersionCode(), "Wrong MPEG version");
assertEquals(AudioFrame.LAYER_2, header.getLayer(), "Wrong layer");
assertEquals(481, header.getLength(), "Wrong frame length");
assertEquals(48.0f, header.getDuration(), 0.01f, "Wrong duration");
}
/**
* Tries to skip a frame if no current header is available.
*/
@Test
public void testSkipNoCurrentHeader() throws IOException {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bos.write("This is a test".getBytes(UTF_8));
TikaInputStream tis = TikaInputStream.get(bos.toByteArray());
stream = new MpegStream(tis);
assertFalse(stream.skipFrame(), "Wrong result");
}
}