Android MediaCodec AAC编码器

Question

我使用MediaCodecAndroid SDK提供的类,因为API级别16与OMX.SEC.aac.enc编码器一起将音频编码为文件.我从AudioRecord课堂上得到了音频输入.我的AudioRecord类实例配置如下:

bufferSize = AudioRecord.getMinBufferSize(44100, AudioFormat.CHANNEL_IN_STEREO, AudioFormat.ENCODING_PCM_16BIT);
recorder = new AudioRecord(MediaRecorder.AudioSource.MIC, 44100, AudioFormat.CHANNEL_IN_STEREO, AudioFormat.ENCODING_DEFAULT, bufferSize);

我能够从AudioRecord实例播放原始数据,因此问题不在那里.

我将AudioRecord实例的输出写入ByteBuffer实例并将其传递给编码器的可用输入缓冲区.编码器的输出被写入SD卡上的文件.

这些是我的MediaCodec实例的配置参数:

codec = MediaCodec.createEncoderByType("audio/mp4a-latm");
MediaFormat format = new MediaFormat();
format.setString(MediaFormat.KEY_MIME, "audio/mp4a-latm");
format.setInteger(MediaFormat.KEY_BIT_RATE, 64 * 1024);
format.setInteger(MediaFormat.KEY_CHANNEL_COUNT, 2);
format.setInteger(MediaFormat.KEY_SAMPLE_RATE, 44100);
format.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectHE);
codec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);

VLC告诉我,我的aac文件中没有流.该命令FFMPEG -i @filename@给出了以下错误:处理输入时找到无效数据.我测试过的所有媒体播放器都无法播放我的文件.

为什么我无法播放我的文件？我没有收到OpenMAX错误,LogCat应用程序在编码时不会崩溃.我写了一个视频编码器,它的工作原理与之相同.

这是将数据从AudioRecord实例读取到缓冲区的代码:

    new Thread() {
        public void run() {
            ByteBuffer byteBuffer = ByteBuffer.allocateDirect(bufferSize);
            int read = 0;
            while (isRecording) {
                read = recorder.read(byteBuffer, bufferSize);
                if(AudioRecord.ERROR_INVALID_OPERATION != read){
                    encoder.add(byteBuffer);
                }
            }
            recorder.stop();
        }
    }.start();

我的编码器添加的函数将一个缓冲区的内容复制到另一个缓冲区:

public void add(ByteBuffer input) {
    if (!isRunning)
        return; 

    if (tmpInputBuffer == null)
        tmpInputBuffer = ByteBuffer.allocate(input.capacity());

    if (!tmpBufferClear)
        Log.e("audio encoder", "deadline missed"); //TODO lower bit rate

    synchronized (tmpInputBuffer) {
        tmpInputBuffer.clear();
        tmpInputBuffer.put(input);
        tmpInputBuffer.notifyAll();
        Log.d("audio encoder", "pushed data into tmpInputBuffer");
    }
}

以下代码用于占用编码器的输入缓冲区:

new Thread() {
    public void run() {
        while (isRunning) {
            if (tmpInputBuffer == null)
                continue;
            synchronized (tmpInputBuffer) {
                if (tmpBufferClear) {
                    try {
                        Log.d("audio encoder", "falling asleep");
                        tmpInputBuffer.wait(); //wait when no input is available
                    } 
                    catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }

                ByteBuffer[] inputBuffers = codec.getInputBuffers();
                int inputBufferIndex;
                do
                    inputBufferIndex = codec.dequeueInputBuffer(-1);
                while (inputBufferIndex < 0);
                ByteBuffer inputBuffer = inputBuffers[inputBufferIndex];
                inputBuffer.clear();
                Log.d("input buffer size", String.valueOf(inputBuffer.capacity()));
                Log.d("tmp input buffer size", String.valueOf(tmpInputBuffer.capacity()));
                inputBuffer.put(tmpInputBuffer.array());
                tmpInputBuffer.clear();
                codec.queueInputBuffer(inputBufferIndex, 0, tmpInputBuffer.capacity(), 0, 0);
                tmpBufferClear = true;
                Log.d("audio encoder", "added to input buffer");
            }
        }
    }
}.start();

我将编码器的输出写入本地文件,如下所示:

    new Thread() {
        public void run() {
            while (isRunning) {
                ByteBuffer[] outputBuffers = codec.getOutputBuffers();
                MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
                int outputBufferIndex = codec.dequeueOutputBuffer(bufferInfo, -1);
                while (outputBufferIndex >= 0) {
                    ByteBuffer outputBuffer = outputBuffers[outputBufferIndex];
                    byte[] outData = new byte[bufferInfo.size];
                    outputBuffer.get(outData);

                    try {
                        fileWriter.write(outData, 0, outData.length);
                    } 
                    catch (IOException e) {
                        e.printStackTrace();
                    }
                    codec.releaseOutputBuffer(outputBufferIndex, false);
                    outputBufferIndex = codec.dequeueOutputBuffer(bufferInfo, 0);
                    Log.d("audio encoder", "removed from output buffer");
                }
            }
            codec.stop();

            try {
                fileWriter.close();
            } 
            catch (IOException e) {
                e.printStackTrace();
            }
        }
    }.start();
                tmpBufferClear = true;
                Log.d("audio encoder", "added to input buffer");
            }
        }
    }
}.start();

Answer 1

我猜你错过了MediaMuxer课程。例如，如果您想将从 MediaCodec 获取的内容写入文件，则需要它。