问题很简单，但是我没有任何解决的线索:
我写了一行代码在我的 Nexus 4 (Android 4.4.2) 上创建一个 AAC 编码器
MediaCodec codec = MediaCodec.createEncoderByType("audio/mp4a-latm");
保存在“codec”中的返回值不为null，但我在Logcat中收到红色错误信息:
03-20 15:25:08.985: E/OMXMaster(24517): A component of name 'OMX.qcom.audio.decoder.aac' already exists, ignoring this one.
我也试过另一条线:
MediaCodec codec = MediaCodec.createByCodecName("OMX.google.aac.encoder");
并得到相同的错误结果。
在使用 MediaCodec 之前我是否遗漏了任何初始化步骤？我没有在官方文档中找到任何关于这方面的信息。
有人遇到过这个问题吗？
实际上我正在尝试将 PCM 编码为 AAC 文件。我读过这个post @胡贝尔。看来他已经成功了。我做了同样的事情:(1)设置媒体解码器并输入 PCM 数据以获得编码帧。为此，我阅读了 cts 中的代码.每个编码帧长度约为 371-379。 (2)在frame中添加adts header，然后保存到文件中。我一点一点地检查了头部，是正确的。但该文件仍然无法播放。所以我认为错误日志可能是问题所在。
以下是我的全部代码，供引用:
MediaCodec codec = MediaCodec.createByCodecName("OMX.google.aac.encoder");
MediaFormat format = new MediaFormat();
format.setString(MediaFormat.KEY_MIME, "audio/mp4a-latm");
format.setInteger(MediaFormat.KEY_AAC_PROFILE,
MediaCodecInfo.CodecProfileLevel.AACObjectELD);
format.setInteger(MediaFormat.KEY_SAMPLE_RATE, nSamplerate);
format.setInteger(MediaFormat.KEY_BIT_RATE, 128000);
format.setInteger(MediaFormat.KEY_CHANNEL_COUNT, nChannels);
codec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
codec.start();
ByteBuffer[] inputBuffers = codec.getInputBuffers();
ByteBuffer[] outputBuffers = codec.getOutputBuffers();
boolean bEndInput = false;
boolean bEndOutput = false;
while(true)
{
if (!bEndInput)
{
int inputBufferIndex = codec.dequeueInputBuffer(0);
if (inputBufferIndex >= 0)
{
int nLen = app.readPCM(nHandle,inputBuffers[inputBufferIndex]);//This line read PCM, return 0 if end of data.
int nBufLen = inputBuffers[inputBufferIndex].capacity();
if (nLen == nBufLen)
codec.queueInputBuffer(inputBufferIndex, 0, nLen, 0, MediaCodec.BUFFER_FLAG_SYNC_FRAME);
else if (nLen < nBufLen)
{
codec.queueInputBuffer(inputBufferIndex, 0, nLen, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
bEndInput = true;
break;
}
}
}
MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();
if (!bEndOutput)
{
int outputBufferIndex = codec.dequeueOutputBuffer(info, 0);
if (outputBufferIndex >= 0)
{
int outBitsSize = info.size;
Log.d("test", "Offset:"+info.offset);
Log.d("test", "Size:"+info.size);
Log.d("test", "Time:"+info.presentationTimeUs);
Log.d("test", "Flags:"+info.flags);
if (outBitsSize <= 10)
{
codec.releaseOutputBuffer(outputBufferIndex, false /* render */);
continue;
}
int outPacketSize = outBitsSize + 7; // 7 is ADTS size
ByteBuffer outBuf = outputBuffers[outputBufferIndex];
outBuf.position(info.offset);
outBuf.limit(info.offset + outBitsSize);
try {
byte[] data = new byte[outPacketSize]; //space for ADTS header included
addADTStoPacket(data, outPacketSize);
outBuf.get(data, 7, outBitsSize);
outBuf.position(info.offset);
outputStream.write(data, 0, outPacketSize); //open FileOutputStream beforehand
} catch (IOException e) {
Log.e("test", "failed writing bitstream data to file");
e.printStackTrace();
}
outBuf.clear();
codec.releaseOutputBuffer(outputBufferIndex, false /* render */);
Log.d("test", " dequeued " + outBitsSize + " bytes of output data.");
Log.d("test", " wrote " + outPacketSize + " bytes into output file.");
if (info.flags == MediaCodec.BUFFER_FLAG_END_OF_STREAM)
{
bEndOutput = true;
//break;
}
}
else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED)
{
outputBuffers = codec.getOutputBuffers();
}
else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED)
{
}
}
if (bEndInput && bEndOutput)
break;
}
最佳答案
我想通了。
(1)媒体格式设置错误:
format.setInteger(MediaFormat.KEY_AAC_PROFILE,
MediaCodecInfo.CodecProfileLevel.AACObjectELD);
应该是
format.setInteger(MediaFormat.KEY_AAC_PROFILE,
MediaCodecInfo.CodecProfileLevel.AACObjectLC);
(2)只有当(info.flags == 0)时编码帧才能写入adts文件
(3) 输出文件名后缀为“aac”。 “mp4”或“m4a”可能不适用于某些应用程序。
MediaCodec codec = MediaCodec.createByCodecName("OMX.google.aac.encoder");
MediaFormat format = new MediaFormat();
format.setString(MediaFormat.KEY_MIME, "audio/mp4a-latm");
format.setInteger(MediaFormat.KEY_AAC_PROFILE,
MediaCodecInfo.CodecProfileLevel.AACObjectLC); //fixed version
format.setInteger(MediaFormat.KEY_SAMPLE_RATE, nSamplerate);
format.setInteger(MediaFormat.KEY_BIT_RATE, 128000);
format.setInteger(MediaFormat.KEY_CHANNEL_COUNT, nChannels);
codec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
codec.start();
ByteBuffer[] inputBuffers = codec.getInputBuffers();
ByteBuffer[] outputBuffers = codec.getOutputBuffers();
boolean bEndInput = false;
boolean bEndOutput = false;
while(true)
{
if (!bEndInput)
{
int inputBufferIndex = codec.dequeueInputBuffer(0);
if (inputBufferIndex >= 0)
{
int nLen = app.readPCM(nHandle,inputBuffers[inputBufferIndex]);//This line read PCM, return 0 if end of data.
int nBufLen = inputBuffers[inputBufferIndex].capacity();
if (nLen == nBufLen)
codec.queueInputBuffer(inputBufferIndex, 0, nLen, 0, MediaCodec.BUFFER_FLAG_SYNC_FRAME);
else if (nLen < nBufLen)
{
codec.queueInputBuffer(inputBufferIndex, 0, nLen, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
bEndInput = true;
break;
}
}
}
MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();
if (!bEndOutput)
{
int outputBufferIndex = codec.dequeueOutputBuffer(info, 0);
if (outputBufferIndex >= 0)
{
int outBitsSize = info.size;
Log.d("test", "Offset:"+info.offset);
Log.d("test", "Size:"+info.size);
Log.d("test", "Time:"+info.presentationTimeUs);
Log.d("test", "Flags:"+info.flags);
if (info.flags != 0) //fixed version
{
codec.releaseOutputBuffer(outputBufferIndex, false /* render */);
continue;
}
int outPacketSize = outBitsSize + 7; // 7 is ADTS size
ByteBuffer outBuf = outputBuffers[outputBufferIndex];
outBuf.position(info.offset);
outBuf.limit(info.offset + outBitsSize);
try {
byte[] data = new byte[outPacketSize]; //space for ADTS header included
addADTStoPacket(data, outPacketSize);
outBuf.get(data, 7, outBitsSize);
outBuf.position(info.offset);
outputStream.write(data, 0, outPacketSize); //open FileOutputStream beforehand
} catch (IOException e) {
Log.e("test", "failed writing bitstream data to file");
e.printStackTrace();
}
outBuf.clear();
codec.releaseOutputBuffer(outputBufferIndex, false /* render */);
Log.d("test", " dequeued " + outBitsSize + " bytes of output data.");
Log.d("test", " wrote " + outPacketSize + " bytes into output file.");
if (info.flags == MediaCodec.BUFFER_FLAG_END_OF_STREAM)
{
bEndOutput = true;
//break;
}
}
else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED)
{
outputBuffers = codec.getOutputBuffers();
}
else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED)
{
}
}
if (bEndInput && bEndOutput)
break;
}
关于android - 使用 MediaCodec 创建 AAC 编码器时出错，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/22526714/