如何在android中彼此合并两个音频文件

您不需要FFMPEG，可以使用android中提供的标准编解码器。

   public void playFile(String fileToPlay)    {     // see where we find a suitable autiotrack        MediaExtractor extractor = new MediaExtractor();        try        { extractor.setDataSource(fileToPlay);        }        catch (IOException e)        { out.release(); return;        }   extractor.selectTrack(0);    String fileType=typeForFile(fileToPlay);    if (fileType==null)    {        out.release();        extractor.release();        return;    }    MediaCodec prec = MediaCodec.createDeprerByType(fileType);    MediaFormat wantedFormat=extractor.getTrackFormat(0);    prec.configure(wantedFormat,null,null,0);    prec.start();    ByteBuffer[] inputBuffers = prec.getInputBuffers();    ByteBuffer[] outputBuffers = prec.getOutputBuffers();    // Allocate our own buffer    int maximumBufferSizeBytes = 0;    for(ByteBuffer bb:outputBuffers)    {        int c=bb.capacity();        if (c>maximumBufferSizeBytes) maximumBufferSizeBytes=c;    }    setupBufferSizes(maximumBufferSizeBytes/4);    final MediaCodec.BufferInfo bufferInfo=new MediaCodec.BufferInfo();    MediaFormat format=null;    while(true)    {        long timeoutUs=1000000;        int inputBufferIndex = prec.dequeueInputBuffer(timeoutUs);        if (inputBufferIndex >= 0)        { ByteBuffer targetBuffer = inputBuffers[inputBufferIndex]; int read = extractor.readSampleData(targetBuffer, 0); int flags=extractor.getSampleFlags(); if (read>0)     prec.queueInputBuffer(inputBufferIndex, 0,read, 0, flags); else     prec.queueInputBuffer(inputBufferIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM); extractor.advance();        }        int outputBufferIndex = prec.dequeueOutputBuffer(bufferInfo,timeoutUs);        if (outputBufferIndex >= 0)        { final boolean last = bufferInfo.flags == MediaCodec.BUFFER_FLAG_END_OF_STREAM; int s=bufferInfo.size/4; ByteBuffer bytes=outputBuffers[outputBufferIndex]; ((ByteBuffer)bytes.position(bufferInfo.offset)).asShortBuffer().get(shorts,0,s*2); process(shorts,0,s*2); prec.releaseOutputBuffer(outputBufferIndex, false); if (last)     break;        }        else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED)        { outputBuffers = prec.getOutputBuffers();        }        else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED)        { format = prec.getOutputFormat();        }    }    extractor.release();    prec.stop();    prec.release();

上面的代码处理1个文件的读取。“处理”例程（尚未定义）接收交错的样本数组（左/右/左/右/左/右）。您现在要做的就是将这些通道添加到目标缓冲区。例如

short[] target=new short[LENGTH OF 4 MINUTES];int idx=0;process(short[] audio, int l){  for(int i=0;i<l;i++)  target[idx++]+=audio[i]/2;}

生成的目标数组将包含您覆盖的样本。