Android如何使用MediaRecorder录制音频并输出为原始PCM？

Question

我目前使用MediaRecorder录制音频以生成.m4a,.mp4,.acc和.3gp,并使用VisualizerView可视化每个录制的输出数据.

现在我想用PCM做同样的事情.

我尝试使用带有ENCODING_PCM_16BIT输入的MediaRecorder和几种不同的输出组合.但是这些组合都没有产生原始PCM输出.

我的问题是:如何使用MediaRecorder录制并将结果输出为原始PCM？

Java代码:

public String mFileName = null;
private String fileName = null;
private String fileNamePcm = null;

String formattedDate = new SimpleDateFormat("MM-dd-yyyy_HH-mm-ss").format(new Date());
fileName = formattedDate;
fileNamePcm = formattedDate;

MediaRecorder mRecorder = new MediaRecorder();

startRecording() {

    // Test Format 1 - produced AMR_WB file
    mRecorder.setAudioSamplingRate(44100);
    mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
    mRecorder.setOutputFormat(AudioFormat.CHANNEL_OUT_MONO); // produced AMR_WB file.
    mRecorder.setAudioEncoder(AudioFormat.ENCODING_PCM_16BIT);


    // Test Format 2 - produced 3gp file
    mRecorder.setAudioSamplingRate(44100);
    mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
    mRecorder.setOutputFormat(MediaRecorder.OutputFormat.DEFAULT); // produced 3gp file.
    mRecorder.setAudioEncoder(AudioFormat.ENCODING_PCM_16BIT);


    // Test Format 3 - produced 3gp file
    mRecorder.setAudioSamplingRate(44100);
    mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
    mRecorder.setOutputFormat(MediaRecorder.OutputFormat.DEFAULT); // did not produced a file.
    mRecorder.setAudioEncoder(AudioFormat.ENCODING_PCM_16BIT);
    mRecorder.setOutputFile(fileNamePcm);  // produced 3gp file. // trying to write raw pcm output to file.


    mFileName = Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + "TestRecordings" + "/" + fileName + ".3gp";
    mFileName = Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + "TestRecordings" + "/" + fileNamePcm + ".pcm";

    mRecorder.setOutputFile(mFileName);

    try {
        mRecorder.prepare();
    } catch (IOException e) {
        Log.e(LOG_TAG, "prepare() failed");
    } catch (IllegalStateException e) {
        e.printStackTrace();
    }

    mRecorder.start();

}

Answer 1

要获取原始 PCM 数据，您必须使用AudioRecord 类- 它支持 ENCODING_PCM_8BIT、ENCODING_PCM_16BIT 和 ENCODING_PCM_FLOAT。