Android音频编辑之音频转换PCM与WAV

 //采样率 * 通道数 * 采样位数/8 * 秒数 8000 * 1 * 8/8 * 60 = 480000，大约480k

 //采样率 * 通道数 * 采样位数/8 * 秒数 44100 * 2 * 16/8 * 60 = 10584000，大约10M

 /** * 将音乐文件解码 * * @param musicFileUrl 源文件路径 * @param decodeFileUrl 解码文件路径 * @param startMicroseconds 开始时间 微秒 * @param endMicroseconds 结束时间 微秒 * @param decodeOperateInterface 解码过程回调 */ private boolean decodeMusicFile(String musicFileUrl, String decodeFileUrl, long startMicroseconds, long endMicroseconds, DecodeOperateInterface decodeOperateInterface) { //采样率，声道数，时长，音频文件类型 int sampleRate = 0; int channelCount = 0; long duration = 0; String mime = null; //MediaExtractor, MediaFormat, MediaCodec MediaExtractor mediaExtractor = new MediaExtractor(); MediaFormat mediaFormat = null; MediaCodec mediaCodec = null; //给媒体信息提取器设置源音频文件路径 try { mediaExtractor.setDataSource(musicFileUrl); }catch (Exception ex){ ex.printStackTrace(); try { mediaExtractor.setDataSource(new FileInputStream(musicFileUrl).getFD()); } catch (Exception e) { e.printStackTrace(); LogUtil.e("设置解码音频文件路径错误"); } } //获取音频格式轨信息 mediaFormat = mediaExtractor.getTrackFormat(0); //从音频格式轨信息中读取 采样率，声道数，时长，音频文件类型 sampleRate = mediaFormat.containsKey(MediaFormat.KEY_SAMPLE_RATE) ? mediaFormat.getInteger( MediaFormat.KEY_SAMPLE_RATE) : 44100; channelCount = mediaFormat.containsKey(MediaFormat.KEY_CHANNEL_COUNT) ? mediaFormat.getInteger( MediaFormat.KEY_CHANNEL_COUNT) : 1; duration = mediaFormat.containsKey(MediaFormat.KEY_DURATION) ? mediaFormat.getLong( MediaFormat.KEY_DURATION) : 0; mime = mediaFormat.containsKey(MediaFormat.KEY_MIME) ? mediaFormat.getString(MediaFormat.KEY_MIME) : ""; LogUtil.i("歌曲信息Track info: mime:" + mime + " 采样率sampleRate:" + sampleRate + " channels:" + channelCount + " duration:" + duration); if (TextUtils.isEmpty(mime) || !mime.startsWith("audio/")) { LogUtil.e("解码文件不是音频文件mime:" + mime); return false; } if (mime.equals("audio/ffmpeg")) { mime = "audio/mpeg"; mediaFormat.setString(MediaFormat.KEY_MIME, mime); } if (duration <= 0) { LogUtil.e("音频文件duration为" + duration); return false; } //解码的开始时间和结束时间 startMicroseconds = Math.max(startMicroseconds, 0); endMicroseconds = endMicroseconds <0 ? duration : endmicroseconds; endmicroseconds=Math.min(endMicroseconds, duration); if (startmicroseconds>= endMicroseconds) { return false; } //创建一个解码器 try { mediaCodec = MediaCodec.createDecoderByType(mime); mediaCodec.configure(mediaFormat, null, null, 0); } catch (Exception e) { LogUtil.e("解码器configure出错"); return false; } //得到输出PCM文件的路径 decodeFileUrl = decodeFileUrl.substring(0, decodeFileUrl.lastIndexOf(".")); String pcmFilePath = decodeFileUrl + ".pcm"; //后续解码操作 getDecodeData(mediaExtractor, mediaCodec, pcmFilePath, sampleRate, channelCount, startMicroseconds, endMicroseconds, decodeOperateInterface); return true; }

 /** * 解码数据 */ private void getDecodeData(MediaExtractor mediaExtractor, MediaCodec mediaCodec, String decodeFileUrl, int sampleRate, int channelCount, final long startMicroseconds, final long endMicroseconds, final DecodeOperateInterface decodeOperateInterface) { //初始化解码状态，未解析完成 boolean decodeInputEnd = false; boolean decodeOutputEnd = false; //当前读取采样数据的大小 int sampleDataSize; //当前输入数据的ByteBuffer序号，当前输出数据的ByteBuffer序号 int inputBufferIndex; int outputBufferIndex; //音频文件的采样位数字节数，= 采样位数/8 int byteNumber; //上一次的解码操作时间，当前解码操作时间，用于通知回调接口 long decodeNoticeTime = System.currentTimeMillis(); long decodeTime; //当前采样的音频时间，比如在当前音频的第40秒的时候 long presentationTimeUs = 0; //定义编解码的超时时间 final long timeOutUs = 100; //存储输入数据的ByteBuffer数组，输出数据的ByteBuffer数组 ByteBuffer[] inputBuffers; ByteBuffer[] outputBuffers; //当前编解码器操作的 输入数据ByteBuffer 和 输出数据ByteBuffer，可以从targetBuffer中获取解码后的PCM数据 ByteBuffer sourceBuffer; ByteBuffer targetBuffer; //获取输出音频的媒体格式信息 MediaFormat outputFormat = mediaCodec.getOutputFormat(); MediaCodec.BufferInfo bufferInfo; byteNumber = (outputFormat.containsKey("bit-width") ? outputFormat.getInteger("bit-width") : 0) / 8; //开始解码操作 mediaCodec.start(); //获取存储输入数据的ByteBuffer数组，输出数据的ByteBuffer数组 inputBuffers = mediaCodec.getInputBuffers(); outputBuffers = mediaCodec.getOutputBuffers(); mediaExtractor.selectTrack(0); //当前解码的缓存信息，里面的有效数据在offset和offset+size之间 bufferInfo = new MediaCodec.BufferInfo(); //获取解码后文件的输出流 BufferedOutputStream bufferedOutputStream = FileFunction.getBufferedOutputStreamFromFile(decodeFileUrl); //开始进入循环解码操作，判断读入源音频数据是否完成，输出解码音频数据是否完成 while (!decodeOutputEnd) { if (decodeInputEnd) { return; } decodeTime = System.currentTimeMillis(); //间隔1秒通知解码进度 if (decodeTime - decodeNoticeTime > Constant.OneSecond) { final int decodeProgress = (int) ((presentationTimeUs - startMicroseconds) * Constant.NormalMaxProgress / endMicroseconds); if (decodeProgress > 0) { notifyProgress(decodeOperateInterface, decodeProgress); } decodeNoticeTime = decodeTime; } try { //操作解码输入数据 //从队列中获取当前解码器处理输入数据的ByteBuffer序号 inputBufferIndex = mediaCodec.dequeueInputBuffer(timeOutUs); if (inputBufferIndex >= 0) { //取得当前解码器处理输入数据的ByteBuffer sourceBuffer = inputBuffers[inputBufferIndex]; //获取当前ByteBuffer，编解码器读取了多少采样数据 sampleDataSize = mediaExtractor.readSampleData(sourceBuffer, 0); //如果当前读取的采样数据<0，说明已经完成了读取操作 if (sampleDataSize <0) { decodeInputEnd = true; sampleDataSize = 0; } else { presentationTimeUs = mediaExtractor.getSampleTime(); } //然后将当前ByteBuffer重新加入到队列中交给编解码器做下一步读取操作 mediaCodec.queueInputBuffer(inputBufferIndex, 0, sampleDataSize, presentationTimeUs, decodeInputEnd ? MediaCodec.BUFFER_FLAG_END_OF_STREAM : 0); //前进到下一段采样数据 if (!decodeInputEnd) { mediaExtractor.advance(); } } else { //LogUtil.e("inputBufferIndex" + inputBufferIndex); } //操作解码输出数据 //从队列中获取当前解码器处理输出数据的ByteBuffer序号 outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, timeOutUs); if (outputBufferIndex <0) { //输出ByteBuffer序号<0，可能是输出缓存变化了，输出格式信息变化了 switch (outputBufferIndex) { case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED: outputBuffers = mediaCodec.getOutputBuffers(); LogUtil.e( "MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED [AudioDecoder]output buffers have changed."); break; case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED: outputFormat = mediaCodec.getOutputFormat(); sampleRate = outputFormat.containsKey(MediaFormat.KEY_SAMPLE_RATE) ? outputFormat.getInteger( MediaFormat.KEY_SAMPLE_RATE) : sampleRate; channelCount = outputFormat.containsKey(MediaFormat.KEY_CHANNEL_COUNT) ? outputFormat.getInteger( MediaFormat.KEY_CHANNEL_COUNT) : channelCount; byteNumber = (outputFormat.containsKey("bit-width") ? outputFormat.getInteger("bit-width") : 0) / 8; LogUtil.e( "MediaCodec.INFO_OUTPUT_FORMAT_CHANGED [AudioDecoder]output format has changed to " + mediaCodec.getOutputFormat()); break; default: //LogUtil.e("error [AudioDecoder] dequeueOutputBuffer returned " + outputBufferIndex); break; } continue; } //取得当前解码器处理输出数据的ByteBuffer targetBuffer = outputBuffers[outputBufferIndex]; byte[] sourceByteArray = new byte[bufferInfo.size]; //将解码后的targetBuffer中的数据复制到sourceByteArray中 targetBuffer.get(sourceByteArray); targetBuffer.clear(); //释放当前的输出缓存 mediaCodec.releaseOutputBuffer(outputBufferIndex, false); //判断当前是否解码数据全部结束了 if ((bufferInfo.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) { decodeOutputEnd = true; } //sourceByteArray就是最终解码后的采样数据 //接下来可以对这些数据进行采样位数，声道的转换，但这是可选的，默认是和源音频一样的声道和采样位数 if (sourceByteArray.length > 0 && bufferedOutputStream != null) { if (presentationTimeUs  endMicroseconds) { break; } } catch (Exception e) { LogUtil.e("getDecodeData异常" + e); } } if (bufferedOutputStream != null) { try { bufferedOutputStream.close(); } catch (IOException e) { LogUtil.e("关闭bufferedOutputStream异常" + e); } } //重置采样率，按自己需要是否实现 if (sampleRate != Constant.ExportSampleRate) { Resample(sampleRate, decodeFileUrl); } notifyProgress(decodeOperateInterface, 100); //释放mediaCodec 和 mediaExtractor if (mediaCodec != null) { mediaCodec.stop(); mediaCodec.release(); } if (mediaExtractor != null) { mediaExtractor.release(); } }

 /** * PCM文件转WAV文件 * @param inPcmFilePath 输入PCM文件路径 * @param outWavFilePath 输出WAV文件路径 * @param sampleRate 采样率，例如44100 * @param channels 声道数 单声道：1或双声道：2 * @param bitNum 采样位数，8或16 */ public static void convertPcm2Wav(String inPcmFilePath, String outWavFilePath, int sampleRate, int channels, int bitNum) { FileInputStream in = null; FileOutputStream out = null; byte[] data = new byte[1024]; try { //采样字节byte率 long byteRate = sampleRate * channels * bitNum / 8; in = new FileInputStream(inPcmFilePath); out = new FileOutputStream(outWavFilePath); //PCM文件大小 long totalAudioLen = in.getChannel().size(); //总大小，由于不包括RIFF和WAV，所以是44 - 8 = 36，在加上PCM文件大小 long totalDataLen = totalAudioLen + 36; writeWaveFileHeader(out, totalAudioLen, totalDataLen, sampleRate, channels, byteRate); int length = 0; while ((length = in.read(data)) > 0) { out.write(data, 0, length); } } catch (Exception e) { e.printStackTrace(); } finally { if (in != null) { try { in.close(); } catch (IOException e) { e.printStackTrace(); } } if (out != null) { try { out.close(); } catch (IOException e) { e.printStackTrace(); } } } } /** * 输出WAV文件 * @param out WAV输出文件流 * @param totalAudioLen 整个音频PCM数据大小 * @param totalDataLen 整个数据大小 * @param sampleRate 采样率 * @param channels 声道数 * @param byteRate 采样字节byte率 * @throws IOException */ private static void writeWaveFileHeader(FileOutputStream out, long totalAudioLen, long totalDataLen, int sampleRate, int channels, long byteRate) throws IOException { byte[] header = new byte[44]; header[0] = 'R'; // RIFF header[1] = 'I'; header[2] = 'F'; header[3] = 'F'; header[4] = (byte) (totalDataLen & 0xff);//数据大小 header[5] = (byte) ((totalDataLen >> 8) & 0xff); header[6] = (byte) ((totalDataLen >> 16) & 0xff); header[7] = (byte) ((totalDataLen >> 24) & 0xff); header[8] = 'W';//WAVE header[9] = 'A'; header[10] = 'V'; header[11] = 'E'; //FMT Chunk header[12] = 'f'; // 'fmt ' header[13] = 'm'; header[14] = 't'; header[15] = ' ';//过渡字节 //数据大小 header[16] = 16; // 4 bytes: size of 'fmt ' chunk header[17] = 0; header[18] = 0; header[19] = 0; //编码方式 10H为PCM编码格式 header[20] = 1; // format = 1 header[21] = 0; //通道数 header[22] = (byte) channels; header[23] = 0; //采样率，每个通道的播放速度 header[24] = (byte) (sampleRate & 0xff); header[25] = (byte) ((sampleRate >> 8) & 0xff); header[26] = (byte) ((sampleRate >> 16) & 0xff); header[27] = (byte) ((sampleRate >> 24) & 0xff); //音频数据传送速率,采样率*通道数*采样深度/8 header[28] = (byte) (byteRate & 0xff); header[29] = (byte) ((byteRate >> 8) & 0xff); header[30] = (byte) ((byteRate >> 16) & 0xff); header[31] = (byte) ((byteRate >> 24) & 0xff); // 确定系统一次要处理多少个这样字节的数据，确定缓冲区，通道数*采样位数 header[32] = (byte) (channels * 16 / 8); header[33] = 0; //每个样本的数据位数 header[34] = 16; header[35] = 0; //Data chunk header[36] = 'd';//data header[37] = 'a'; header[38] = 't'; header[39] = 'a'; header[40] = (byte) (totalAudioLen & 0xff); header[41] = (byte) ((totalAudioLen >> 8) & 0xff); header[42] = (byte) ((totalAudioLen >> 16) & 0xff); header[43] = (byte) ((totalAudioLen >> 24) & 0xff); out.write(header, 0, 44); }