在播放解码后的音频时，我设法制作了各种各样的声音，从潺潺到尖锐的恶魔吟唱。最接近的声音类似于在快进和播放中播放仅持续约15秒。我已尝试使用解码和AudioSystem API方法的大量参数组合，似乎没有任何工作。
那么，是什么导致了这种音频失真？
此文件的Opusinfo显示以下内容：
Processing file "test.opus"...
New logical stream (#1, serial: 00002c88): type opus
Encoded with libopus 1.1
User comments section follows...
ENCODER=opusenc from opus-tools 0.1.9
Opus stream 1:
Pre-skip: 356
Playback gain: 0 dB
Channels: 1
Original sample rate: 44100Hz
Packet duration: 20.0ms (max), 20.0ms (avg), 20.0ms (min)
Page duration: 1000.0ms (max), 996.8ms (avg), 200.0ms (min)
Total data length: 1930655 bytes (overhead: 1.04%)
Playback length: 4m:09.173s
Average bitrate: 61.99 kb/s, w/o overhead: 61.34 kb/s
Logical stream 1 ended
使用VLC正确播放此文件。
要解码文件，我正在尝试使用以下库：
VorbisJava（https://github.com/Gagravarr/VorbisJava/） - 从OGG容器中提取框架
LibJitsi（https://jitsi.org/Projects/LibJitsi） - 其中有一个用于Opus的JNI包装器，用于解码opus帧
package me.justinb.mediapad.audio;
import org.gagravarr.ogg.OggFile;
import org.gagravarr.ogg.OggPacket;
import org.jitsi.impl.neomedia.codec.audio.opus.Opus;
import javax.sound.sampled.*;
import java.io.*;
import java.nio.ByteBuffer;
public class OpusAudioPlayer {
private static int BUFFER_SIZE = 1024 * 1024;
private static int INPUT_BITRATE = 48000;
private static int OUTPUT_BITRATE = 44100;
private OggFile oggFile;
private long opusState;
private ByteBuffer decodeBuffer = ByteBuffer.allocate(BUFFER_SIZE);
private AudioFormat audioFormat = new AudioFormat(OUTPUT_BITRATE, 16, 1, true, false);
public static void main(String[] args) {
try {
OpusAudioPlayer opusAudioPlayer = new OpusAudioPlayer(new File("test.opus"));
opusAudioPlayer.play();
} catch (IOException e) {
e.printStackTrace();
}
}
public OpusAudioPlayer(File audioFile) throws IOException {
oggFile = new OggFile(new FileInputStream(audioFile));
opusState = Opus.decoder_create(INPUT_BITRATE, 1);
System.out.println("Audio format: " + audioFormat);
}
private byte[] decode(byte[] packetData) {
int frameSize = Opus.decoder_get_nb_samples(opusState, packetData, 0, packetData.length);
int decodedSamples = Opus.decode(opusState, packetData, 0, packetData.length, decodeBuffer.array(), 0, frameSize, 0);
if (decodedSamples < 0) {
System.out.println("Decode error: " + decodedSamples);
decodeBuffer.clear();
return null;
}
decodeBuffer.position(decodedSamples * 2); // 2 bytes per sample
decodeBuffer.flip();
byte[] decodedData = new byte[decodeBuffer.remaining()];
decodeBuffer.get(decodedData);
decodeBuffer.flip();
System.out.println(String.format("Encoded frame size: %d bytes", packetData.length));
System.out.println(String.format("Decoded frame size: %d bytes", decodedData.length));
System.out.println(String.format("Decoded %d samples", decodedSamples));
return decodedData;
}
public void play() {
int totalDecodedBytes = 0;
try {
SourceDataLine speaker = AudioSystem.getSourceDataLine(audioFormat);
OggPacket nextPacket = oggFile.getPacketReader().getNextPacket();
// Move to beginning of stream
while ( !nextPacket.isBeginningOfStream()) {
nextPacket = oggFile.getPacketReader().getNextPacket();
}
speaker.open();
speaker.start();
while(nextPacket != null) {
// Decode each packet
byte[] decodedData = decode(nextPacket.getData());
if(decodedData != null) {
// Write packet to SourceDataLine
speaker.write(decodedData, 0, decodedData.length);
totalDecodedBytes += decodedData.length;
}
nextPacket = oggFile.getPacketReader().getNextPacket();
}
speaker.drain();
speaker.close();
System.out.println(String.format("Decoded to %d bytes", totalDecodedBytes));
} catch (Exception e) {
e.printStackTrace();
}
}
}
答案 0 :(得分：11)
我的特殊问题似乎是由VorbisJava中的错误引起的。我现在正在使用J-Ogg，它正在处理容器解析而没有任何问题。我确定有人会觉得这很有用。
这是显示如何用Java播放Opus编码音频的最终代码：
package me.justinb.mediapad.audio;
import de.jarnbjo.ogg.FileStream;
import de.jarnbjo.ogg.LogicalOggStream;
import org.jitsi.impl.neomedia.codec.audio.opus.Opus;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.SourceDataLine;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.util.Collection;
public class OpusAudioPlayer {
private static int BUFFER_SIZE = 1024 * 1024;
private static int INPUT_BITRATE = 48000;
private static int OUTPUT_BITRATE = 48000;
private FileStream oggFile;
private long opusState;
private ByteBuffer decodeBuffer = ByteBuffer.allocate(BUFFER_SIZE);
private AudioFormat audioFormat = new AudioFormat(OUTPUT_BITRATE, 16, 1, true, false);
public static void main(String[] args) {
try {
OpusAudioPlayer opusAudioPlayer = new OpusAudioPlayer(new File("test.opus"));
opusAudioPlayer.play();
} catch (IOException e) {
e.printStackTrace();
}
}
public OpusAudioPlayer(File audioFile) throws IOException {
oggFile = new FileStream(new RandomAccessFile(audioFile, "r"));
opusState = Opus.decoder_create(INPUT_BITRATE, 1);
}
private byte[] decode(byte[] packetData) {
int frameSize = Opus.decoder_get_nb_samples(opusState, packetData, 0, packetData.length);
int decodedSamples = Opus.decode(opusState, packetData, 0, packetData.length, decodeBuffer.array(), 0, frameSize, 0);
if (decodedSamples < 0) {
System.out.println("Decode error: " + decodedSamples);
decodeBuffer.clear();
return null;
}
decodeBuffer.position(decodedSamples * 2); // 2 bytes per sample
decodeBuffer.flip();
byte[] decodedData = new byte[decodeBuffer.remaining()];
decodeBuffer.get(decodedData);
decodeBuffer.flip();
return decodedData;
}
public void play() {
int totalDecodedBytes = 0;
try {
SourceDataLine speaker = AudioSystem.getSourceDataLine(audioFormat);
speaker.open();
speaker.start();
for (LogicalOggStream stream : (Collection<LogicalOggStream>) oggFile.getLogicalStreams()) {
byte[] nextPacket = stream.getNextOggPacket();
while (nextPacket != null) {
byte[] decodedData = decode(nextPacket);
if(decodedData != null) {
// Write packet to SourceDataLine
speaker.write(decodedData, 0, decodedData.length);
totalDecodedBytes += decodedData.length;
}
nextPacket = stream.getNextOggPacket();
}
}
speaker.drain();
speaker.close();
System.out.println(String.format("Decoded to %d bytes", totalDecodedBytes));
} catch (Exception e) {
e.printStackTrace();
}
}
}
答案 1 :(得分：-1)
看看你的代码，我假设你错过了＃34;帧长度＆＃34;的含义。您正在获取字节数，但帧长度直接取决于文件的编码方式。
以48000 Hz记录的音频文件每秒有48000个样本。这个音频样本通常是一个16位整数（2个字节），这意味着你将以非编码形式（PCM-WAV）每秒拥有48000 * 2个字节。
像opus这样的音频编码器会同时拍摄多个音频样本并将其编码在一个包中。这是框架。在48 kHz时，这些值可以是opus 120,240,480,960,1920和2880。