Java PCM byte[]转AAC 示例代码

以下是Java PCM byte[]转AAC的示例代码：

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import javax.sound.sampled.AudioFileFormat;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.UnsupportedAudioFileException;
import org.bytedeco.javacpp.avcodec;
import org.bytedeco.javacpp.avutil;
import org.bytedeco.javacpp.opus;
import org.bytedeco.javacpp.presets.opus;
import org.bytedeco.javacv.FFmpegFrameRecorder;
import org.bytedeco.javacv.FrameRecorder.Exception;
import org.bytedeco.javacv.Java2DFrameConverter;

public class AudioConverter {
    private static ByteArrayOutputStream audioOutputStream = new ByteArrayOutputStream();
    private static final int OPUS_SAMPLE_RATE = 48000;
    private static final int OPUS_CHANNEL_COUNT = 2;
    private static final int OPUS_FRAME_SIZE = 1280;
    private static final int RECORDING_DURATION = 60000;
    private static final int RECORDING_START_DELAY = 2000;

    public static void main(String args[]) throws Exception {
        AudioInputStream audioInputStream = null;
        try {
            audioInputStream = AudioSystem.getAudioInputStream(AudioConverter.class.getResourceAsStream("/test.wav"));
        } catch (UnsupportedAudioFileException e) {
            System.out.println("Unsupported file format");
        } catch (IOException e) {
            System.out.println("I/O Exception");
        }

        AudioFormat sourceFormat = audioInputStream.getFormat();
        AudioFormat opusFormat = new AudioFormat(opus.OPUS_SAMPLE_RATE, opus.OPUS_CHANNEL_COUNT, opus.AvSampleFormat.AV_SAMPLE_FMT_S16.getValue(), true, false);

        byte[] audioBytes = null;
        int numBytes = 0;
        byte[] buffer = new byte[4096];
        try {
            while ((numBytes = audioInputStream.read(buffer)) != -1) {
                audioOutputStream.write(buffer, 0, numBytes);
            }
            audioBytes = audioOutputStream.toByteArray();

        } catch (IOException e) {
            e.printStackTrace();
        }

        Java2DFrameConverter java2dConverter = new Java2DFrameConverter();
        FFmpegFrameRecorder frameRecorder = new FFmpegFrameRecorder("test.aac", OPUS_SAMPLE_RATE);
        frameRecorder.setAudioChannels(OPUS_CHANNEL_COUNT);
        frameRecorder.setAudioOption("ac", "2");
        frameRecorder.setAudioOption("ar", Integer.toString(OPUS_SAMPLE_RATE));
        frameRecorder.setAudioOption("sample_fmt", "s16p");
        frameRecorder.setAudioOption("preset", "ultrafast");
        frameRecorder.setAudioOption("tune", "zerolatency");
        frameRecorder.setAudioOption("compression_level", "10");

        try {
            frameRecorder.start();
            frameRecorder.setTimestamp(0);
            long startTime = System.currentTimeMillis() + RECORDING_START_DELAY;
            long endTime = startTime + RECORDING_DURATION;

            int startTimeIndex = (int) ((RECORDING_START_DELAY / 1000) * sourceFormat.getFrameRate()) * sourceFormat.getFrameSize();
            int endTimeIndex = (int) ((RECORDING_DURATION / 1000) * sourceFormat.getFrameRate()) * sourceFormat.getFrameSize();

            for (int i = startTimeIndex; i < endTimeIndex; i += sourceFormat.getFrameSize()) {
                byte[] opusBuffer = new byte[OPUS_FRAME_SIZE * OPUS_CHANNEL_COUNT * 2];
                int numBytesRead = 0;
                for (int j = 0; j < OPUS_FRAME_SIZE; j++) {
                    if ((i + j * sourceFormat.getFrameSize()) < audioBytes.length) {
                        opusBuffer[numBytesRead++] = audioBytes[i + j * sourceFormat.getFrameSize()];
                        opusBuffer[numBytesRead++] = audioBytes[i + j * sourceFormat.getFrameSize() + 1];
                    }
                }
                frameRecorder.recordSamples(avutil.avSampleFormatValue(opusFormat.getSampleSizeInBits()), opusBuffer, OPUS_CHANNEL_COUNT);
                long currentTimestamp = System.currentTimeMillis() - startTime;
                frameRecorder.setTimestamp(currentTimestamp);
                Thread.sleep(Math.max(0, 20 - currentTimestamp));
            }
        } catch (org.bytedeco.javacv.FrameRecorder.Exception e) {
            System.out.println("Could not start recording");
        } catch (InterruptedException e) {
            System.out.println("Current thread interrupted");
        } finally {
            try {
                frameRecorder.stop();
            } catch (org.bytedeco.javacv.FrameRecorder.Exception e) {
                System.out.println("Could not stop recording");
            }
        }
    }
}