使用mediacodec进行PCM到AAC的转换

Question

我正在使用Android中的一个媒体编解码器类（Jelly Bean）将PCM格式编码为AAC。该文件已编码，但没有音乐播放器能够播放该文件。我在网上找不到任何工作代码或适当的文档。

这是我的代码：

public void doConvert()
{

    new AsyncTask<Void, Void, Void>()
    {

        @Override
        protected Void doInBackground(Void... params) 
        {
            try
            {
                int codecCount = MediaCodecList.getCodecCount();

                for ( int i=0; i < codecCount; i++)
                {
                    MediaCodecInfo info = MediaCodecList.getCodecInfoAt(i);
                    Logger.getLogger(MainActivity.class.getSimpleName()).log(Level.INFO, info.getName());
                    for ( String type : info.getSupportedTypes() )
                    {
                        Logger.getLogger(MainActivity.class.getSimpleName()).log(Level.INFO, type);
                    }

                }

                File inputFile = new File( Environment.getExternalStorageDirectory().getAbsolutePath()+"/Download/Ghajini27_Mono_8Khz.wav");
                //File inputFile = new File( sampleFD.get);
                Log.e("File", String.valueOf(inputFile.length()));
                FileInputStream fis = new FileInputStream(inputFile);
                fis.skip(44);//remove wav header

                File outputFile = new File( Environment.getExternalStorageDirectory().getAbsolutePath()+"/Download/out.m4a");
                if ( outputFile.exists()) outputFile.delete();

                FileOutputStream fos = new FileOutputStream(outputFile);

                //BufferedOutputStream bos=new BufferedOutputStream(new FileOutputStream(outputFile));
                MediaCodec codec = MediaCodec.createEncoderByType("audio/mp4a-latm");
                MediaFormat outputFormat = MediaFormat.createAudioFormat("audio/mp4a-latm", 22050, 1);
                outputFormat.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC);
             //  outputFormat.setInteger(MediaFormat.KEY_CHANNEL_MASK, AudioFormat.CHANNEL_CONFIGURATION_MONO);
                outputFormat.setInteger(MediaFormat.KEY_BIT_RATE, 22050  );
                outputFormat.setInteger(MediaFormat.KEY_CHANNEL_COUNT, 1);
                //outputFormat.setLong(MediaFormat.KEY_MAX_INPUT_SIZE, inputFile.length());
                double durationInMs = (inputFile.length()/16000)*1000;
                Log.e("duration",String.valueOf((long)durationInMs));
                outputFormat.setLong(MediaFormat.KEY_DURATION, (long)durationInMs );


                codec.configure(outputFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE );
                codec.start();

                ByteBuffer[] inputBuffers = codec.getInputBuffers();
                ByteBuffer[] outputBuffer = codec.getOutputBuffers();

                boolean hasMoreData = true;   
                MediaCodec.BufferInfo outBuffInfo = new BufferInfo();
                byte readBuffer[] = new byte[48000];
                byte writeBuffer[] = new byte[48000];

                do
                {
                   int nextBuffer = codec.dequeueInputBuffer(5000);
                   Log.e("NextBuffer","nextInputBuffer = "+nextBuffer);

                    if ( nextBuffer >= 0 )
                    {



                        ByteBuffer inBuf = inputBuffers[nextBuffer];
                        inBuf.clear();
                        int bytesRead = fis.read( readBuffer,0, inBuf.capacity() );

                        Log.e("bytesread","Read = "+bytesRead);

                        if ( bytesRead < inBuf.capacity() )
                        {
                            hasMoreData = false;
                        }

                        inBuf.put(readBuffer, 0, bytesRead);

                        codec.queueInputBuffer(nextBuffer, 0, bytesRead, 0, hasMoreData?0:MediaCodec.BUFFER_FLAG_END_OF_STREAM);
                    }


                    int outputBufferIndex = codec.dequeueOutputBuffer( outBuffInfo, 3000);
                /*    logger.log(Level.INFO,"nextOutputBuffer = "+outputBufferIndex);
                    logger.log(Level.INFO,"outBuffInfo offset = "+outBuffInfo.offset);
                    logger.log(Level.INFO,"outBuffInfo size = "+outBuffInfo.size);
                    logger.log(Level.INFO,"outBuffInfo flags = "+outBuffInfo.flags);*/


                    //while ( outputBufferIndex > -1 )
                    //{ 

                        outputBuffer[outputBufferIndex].position(outBuffInfo.offset);
                        outputBuffer[outputBufferIndex].get(writeBuffer,0,outBuffInfo.size);

                        fos.write(writeBuffer,0, outBuffInfo.size);
                      //  logger.log(Level.INFO,"Writing = "+outBuffInfo.size+" bytes");


                        outputBuffer[outputBufferIndex].clear();

                        codec.releaseOutputBuffer(outputBufferIndex, false);

                        if ( outBuffInfo.flags == MediaCodec.BUFFER_FLAG_END_OF_STREAM )
                        {
                            codec.flush();
                            codec.stop();
                            codec.release();
                            break;
                        }

                        //outputBufferIndex = codec.dequeueOutputBuffer( outBuffInfo, 1000 );
                        //logger.log(Level.INFO,"nextOutputBuffer = "+outputBufferIndex);
                    //}

                } while (outBuffInfo.flags != MediaCodec.BUFFER_FLAG_END_OF_STREAM);

                fis.close();
                fos.flush();
                fos.close();



            }
            catch ( Exception e)
            {
                //Logger.getLogger(MainActivity.class.getSimpleName()).log(Level.INFO, "Codec Error",e);
            }

            //logger.log(Level.INFO,"Done");

            return null;
        }

    }.execute();
}

Answer 1

你需要一个容器。将MediaCodec的编码输出发送到MediaMuxer。使用mp4作为容器类型。不需要使用@Andy--S发布的神秘代码。

只需确保为最终文件提供一个扩展名。m4a而不是mp4。MP4扩展用于视频。

有关MediaMuxer的详细信息，请参阅：https://developer.android.com/reference/android/media/MediaMuxer#writeSampleData（int，java.nio.ByteBuffer，android.media.MediaCodec.BufferInfo）

Answer 2

有一个AndroidAAC库https://github.com/timsu/android-aac-enc

尝试通过这个库传递您的缓冲区。这可能会有所帮助。

Answer 3

你需要为它选择一个容器。我更喜欢ADT。

将有效载荷数据复制到一个足以容纳您的容器的区域中，只需添加您的位即可。因此，在互联网上搜索我的解决方案后，我将一些片段放在适当的位置

方法“fillInADTSHeader”

    profile =( configParams[0]>>3 )&0x1f;

    frequency_index = (this.configParams[0]&0x7) <<1 | (this.configParams[1]>>7) &0x1;

    channel_config = (this.configParams[1]>>3) &0xf;

    int finallength = encoded_length + 7;       
    ENCodedByteArray[0] = (byte) 0xff;
    ENCodedByteArray[1] = (byte) 0xf1;
    ENCodedByteArray[2] = (byte) ( ((profile - 1) << 6) + (frequency_index << 2) +(channel_config >> 2));
    ENCodedByteArray[3] = (byte) (((channel_config & 0x3) << 6) + (finallength >> 11));
    ENCodedByteArray[4] = (byte)( (finallength & 0x7ff) >> 3);
    ENCodedByteArray[5] = (byte) (((finallength & 7) << 5) + 0x1f) ;
    ENCodedByteArray[6] = (byte) 0xfc;

使用类似

            byte chunkADTS[]=new byte[info.size + 7];
            fillInADTSHeader(chunkADTS,info.size);
            outputBuffers[bR].get(chunkADTS,7,info.size);
            buffer.pushData(chunkADTS);

应该在shoutcast等中播放...