我只想对音频文件进行一些处理而不播放它们。我怀疑我做得对吗，还有几个问题。我读了一些示例，但其中大多数都是关于视频流的，根本没有处理原始数据。
L R L R L R ...}，对吗？例如。:{
105 105 601 601 -243 -243 -484 -484 ...}。但是我得到一对接近的数字，但不相等:
{
-308 -264 -1628 -1667 -2568 -2550 -4396 -4389}mp3算法对相同值的编码是否不同？为什么？
mExcess)。是否可以保证订单会得到保留？ MediaExtractor::readSampleData和MediaExtractor::advance方法。第一个返回〜2000的值，第二个描述为“前进到下一个样本”。这只是命名的重叠吗？我看到了几个示例，其中这些方法是成对循环调用的。我的用法正确吗？ 这是我的代码:
public static void foo(String filepath) throws IOException {
final int SAMPLES_PER_CHUNK = 1024;
MediaExtractor mediaExtractor = new MediaExtractor();
mediaExtractor.setDataSource(filepath);
MediaFormat mediaFormat = mediaExtractor.getTrackFormat(0);
mediaExtractor.release();
MediaCodecList mediaCodecList = new MediaCodecList(MediaCodecList.ALL_CODECS);
mediaFormat.setString(MediaFormat.KEY_FRAME_RATE, null);
String codecName = mediaCodecList.findDecoderForFormat(mediaFormat);
mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE, 0); // MediaCodec crashes with JNI
// error if FRAME_RATE is null
MediaCodec mediaCodec = MediaCodec.createByCodecName(codecName);
mediaCodec.setCallback(new MediaCodec.Callback() {
private MediaExtractor mExtractor;
private short[] mExcess;
@Override
public void onInputBufferAvailable(MediaCodec codec, int index) {
if (mExtractor == null) {
mExtractor = new MediaExtractor();
try {
mExtractor.setDataSource(filepath);
mExtractor.selectTrack(0);
} catch (IOException e) {
e.printStackTrace();
}
mExcess = new short[0];
}
ByteBuffer in = codec.getInputBuffer(index);
in.clear();
int sampleSize = mExtractor.readSampleData(in, 0);
if (sampleSize > 0) {
boolean isOver = !mExtractor.advance();
codec.queueInputBuffer(
index,
0,
sampleSize,
mExtractor.getSampleTime(),
isOver ? MediaCodec.BUFFER_FLAG_END_OF_STREAM : 0);
} else {
int helloAmaBreakpoint = 1;
}
}
@Override
public void onOutputBufferAvailable(
MediaCodec codec,
int index,
MediaCodec.BufferInfo info) {
ByteBuffer tmp = codec.getOutputBuffer(index);
if (tmp.limit() == 0) return;
ShortBuffer out = tmp.order(ByteOrder.nativeOrder()).asShortBuffer();
// Prepend the remainder from previous batch to the new data
short[] buf = new short[mExcess.length + out.limit()];
System.arraycopy(mExcess, 0, buf, 0, mExcess.length);
out.get(buf, mExcess.length, out.limit());
final int channelCount
= codec.getOutputFormat().getInteger(MediaFormat.KEY_CHANNEL_COUNT);
for (
int offset = 0;
offset + SAMPLES_PER_CHUNK * channelCount < buf.length;
offset += SAMPLES_PER_CHUNK * channelCount) {
double[] x = new double[SAMPLES_PER_CHUNK]; // left channel
double[] y = new double[SAMPLES_PER_CHUNK]; // right channel
switch (channelCount) {
case 1: // if 1 channel then make 2 identical arrays
for (int i = 0; i < SAMPLES_PER_CHUNK; ++i) {
x[i] = (double) buf[offset + i];
y[i] = (double) buf[offset + i];
}
break;
case 2: // if 2 channels then read values alternately
for (int i = 0; i < SAMPLES_PER_CHUNK; ++i) {
x[i] = (double) buf[offset + i * 2];
y[i] = (double) buf[offset + i * 2 + 1];
}
break;
default:
throw new IllegalStateException("No algorithm for " + channelCount + " channels");
}
/// ... some processing ... ///
}
// Save the rest until next batch of raw data
int samplesLeft = buf.length % (SAMPLES_PER_CHUNK * channelCount);
mExcess = new short[samplesLeft];
System.arraycopy(
buf,
buf.length - samplesLeft,
mExcess,
0,
samplesLeft);
codec.releaseOutputBuffer(index, false);
if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) > 0) {
codec.stop();
codec.release();
mExtractor.release();
}
}
@Override
public void onError(MediaCodec codec, MediaCodec.CodecException e) {
}
@Override
public void onOutputFormatChanged(MediaCodec codec, MediaFormat format) {
}
});
mediaFormat.setInteger(MediaFormat.KEY_PCM_ENCODING, AudioFormat.ENCODING_PCM_16BIT);
mediaCodec.configure(mediaFormat, null, null, 0);
mediaCodec.start();
}
也欢迎快速代码审查。
最佳答案