如何攔截Android設備上的音頻流？

Question

讓我們假設我們有以下場景：在Android設備上播放的東西（一個mp3的例子，但它可能是任何使用Android設備的音頻部分的東西）。 從一個應用程序（Android應用程序:)），我想攔截音頻流來分析它，記錄它，等等。從這個應用程序（讓我們說“分析器”）我不想啟動一個MP3或東西，我想要的只是訪問Android的音頻流。

任何建議都表示贊賞，它可以是Java或C ++解決方案。

Answer 1

http://developer.android.com/reference/android/media/MediaRecorder.html

    public class AudioRecorder {

    final MediaRecorder recorder = new MediaRecorder();
    final String path;

    /**
     * Creates a new audio recording at the given path (relative to root of SD
     * card).
     */
    public AudioRecorder(String path) {
        this.path = sanitizePath(path);
    }

    private String sanitizePath(String path) {
        if (!path.startsWith("/")) {
            path = "/" + path;
        }
        if (!path.contains(".")) {
            path += ".3gp";
        }
        return Environment.getExternalStorageDirectory().getAbsolutePath()
                + path;
    }

    /**
     * Starts a new recording.
     */
    public void start() throws IOException {
        String state = android.os.Environment.getExternalStorageState();
        if (!state.equals(android.os.Environment.MEDIA_MOUNTED)) {
            throw new IOException("SD Card is not mounted.  It is " + state
                    + ".");
        }

        // make sure the directory we plan to store the recording in exists
        File directory = new File(path).getParentFile();
        if (!directory.exists() && !directory.mkdirs()) {
            throw new IOException("Path to file could not be created.");
        }

        recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
        recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
        recorder.setOutputFile(path);
        recorder.prepare();
        recorder.start();
    }

    /**
     * Stops a recording that has been previously started.
     */
    public void stop() throws IOException {
        recorder.stop();
        recorder.release();
    }
}