拉梅EN codeD MP3音频放缓 - Android电子 [英] Lame encoded mp3 audio slowed down - Android

问题描述

我一直在下面<一个href=\"http://developer.samsung.com/android/technical-docs/Porting-and-using-LAME-MP3-on-Android-with-JNI\"相对=nofollow>使用LAME MP3在Android用JNI本教程。录像似乎是工作，我得到一个输出为MP3，但在播放音频已经放缓，一头栽倒。

I have been following this tutorial on using LAME mp3 on Android with jni. Recording seems to be working and I am getting an output as mp3 but upon playback the audio has been slowed down and pitched down.

我试图把所有相关的code以下。为什么这所有的指导是怎么回事？在此先感谢您的帮助。

I've tried to put all pertinent code below. Any guidance on why this is happening? Thanks in advance for your help.

的编辑：的行，所以只是为了检查我导入的原始数据转换成无畏和回放细所以这必须在编码阶段的问题。

OK so just to check I imported the raw data into Audacity and that plays back fine so this must be an issue at the encoding stage.

的 Java类：的

public class Record extends Activity implements OnClickListener {

    static {
        System.loadLibrary("mp3lame");
    }

    private native void initEncoder(int numChannels, int sampleRate, int bitRate, int mode, int quality);

    private native void destroyEncoder();

    private native int encodeFile(String sourcePath, String targetPath);

    private static final int RECORDER_BPP = 16;
    private static final String AUDIO_RECORDER_FILE_EXT_WAV = ".wav";
    private static final String AUDIO_RECORDER_FOLDER = "AberdeenSoundsites";
    private static final String AUDIO_RECORDER_TEMP_FILE = "record_temp.raw";
    private static final int[] RECORDER_SAMPLERATES = {44100, 22050, 11025, 8000};
    private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_STEREO;
    private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;

    public static final int NUM_CHANNELS = 2;
    public static final int SAMPLE_RATE = 44100;
    public static final int BITRATE = 320;
    public static final int MODE = 1;
    public static final int QUALITY = 2;
        private short[] mBuffer;
    private File rawFile;
    private File encodedFile;

    private int sampleRate;
    private String filename;

    private AudioRecord recorder = null;
    private int bufferSize = 0;
    private Thread recordingThread = null;
    private boolean isRecording = false;


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.record);

        initEncoder(NUM_CHANNELS, SAMPLE_RATE, BITRATE, MODE, QUALITY);

        stopButton = (Button) findViewById(R.id.stop_button);
        stopButton.setOnClickListener(this);
        timer = (TextView) findViewById(R.id.recording_time);

        bufferSize = AudioRecord.getMinBufferSize(44100, RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING);
    }

    private void startRecording() {
        stopped = false;
        stopButton.setText(R.string.stop_button_label);

        // Set up and start audio recording
        recorder = findAudioRecord();
        recorder.startRecording();
        isRecording = true;

        rawFile = getFile("raw");
        mBuffer = new short[bufferSize];
        startBufferedWrite(rawFile);
        }

    private void stopRecording() {
        mHandler.removeCallbacks(startTimer);
        stopped = true;

        if(recorder != null){
            isRecording = false;

            recorder.stop();
            recorder.release();

            recorder = null;
            recordingThread = null;
        }

        encodedFile = getFile("mp3");
        int result = encodeFile(rawFile.getAbsolutePath(), encodedFile.getAbsolutePath());
        if (result == 0) {
            Toast.makeText(Record.this, "Encoded to " + encodedFile.getName(), Toast.LENGTH_SHORT)
                    .show();
        }
    }

    private void startBufferedWrite(final File file) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                Looper.prepare();
                DataOutputStream output = null;
                try {
                    output = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(file)));
                    while (isRecording) {
                        int readSize = recorder.read(mBuffer, 0, mBuffer.length);
                        for (int i = 0; i < readSize; i++) {
                            output.writeShort(mBuffer[i]);
                        }
                    }
                } catch (IOException e) {
                    Toast.makeText(Record.this, e.getMessage(), Toast.LENGTH_SHORT).show();
                } finally {
                    if (output != null) {
                        try {
                            output.flush();
                        } catch (IOException e) {
                            Toast.makeText(Record.this, e.getMessage(), Toast.LENGTH_SHORT).show();
                        } finally {
                            try {
                                output.close();
                            } catch (IOException e) {
                                Toast.makeText(Record.this, e.getMessage(), Toast.LENGTH_SHORT).show();
                            }
                        }
                    }
                }
            }
        }).start();
    }

    private File getFile(final String suffix) {
        Time time = new Time();
        time.setToNow();
        return new File(Environment.getExternalStorageDirectory()+"/MyAppFolder", time.format("%Y%m%d%H%M%S") + "." + suffix);
    }

    public AudioRecord findAudioRecord() {
        for (int rate : RECORDER_SAMPLERATES) {
            for (short audioFormat : new short[] { AudioFormat.ENCODING_PCM_16BIT, AudioFormat.ENCODING_PCM_8BIT }) {
                for (short channelConfig : new short[] { AudioFormat.CHANNEL_IN_STEREO, AudioFormat.CHANNEL_IN_MONO  }) {
                    try {
                        Log.d("AberdeenSoundsites", "Attempting rate " + rate + "Hz, bits: " + audioFormat + ", channel: "
                                + channelConfig);
                        int bufferSize = AudioRecord.getMinBufferSize(rate, channelConfig, audioFormat);

                        if (bufferSize != AudioRecord.ERROR_BAD_VALUE) {
                            // check if we can instantiate and have a success
                            AudioRecord recorder = new AudioRecord(MediaRecorder.AudioSource.MIC, rate, channelConfig, audioFormat, bufferSize);
                            sampleRate = rate;
                            if (recorder.getState() == AudioRecord.STATE_INITIALIZED)
                                return recorder;
                        }
                    } catch (Exception e) {
                        Log.e("MyApp", rate + "Exception, keep trying.",e);
                    }
                }
            }
        }
        Log.e("MyApp", "No settings worked :(");
        return null;
    }

的 C包装：的

#include <stdio.h>
#include <stdlib.h>
#include <jni.h>
#include <android/log.h> 
#include "libmp3lame/lame.h"

#define LOG_TAG "LAME ENCODER"
#define LOGD(format, args...)  __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, format, ##args);
#define BUFFER_SIZE 8192
#define be_short(s) ((short) ((unsigned short) (s) << 8) | ((unsigned short) (s) >> 8))

lame_t lame;

int read_samples(FILE *input_file, short *input) {
    int nb_read;
    nb_read = fread(input, 1, sizeof(short), input_file) / sizeof(short);

    int i = 0;
    while (i < nb_read) {
        input[i] = be_short(input[i]);
        i++;
    }

    return nb_read;
}

void Java_myPacakage_myApp_Record_initEncoder(JNIEnv *env,
        jobject jobj, jint in_num_channels, jint in_samplerate, jint in_brate,
        jint in_mode, jint in_quality) {
    lame = lame_init();

    LOGD("Init parameters:");
    lame_set_num_channels(lame, in_num_channels);
    LOGD("Number of channels: %d", in_num_channels);
    lame_set_in_samplerate(lame, in_samplerate);
    LOGD("Sample rate: %d", in_samplerate);
    lame_set_brate(lame, in_brate);
    LOGD("Bitrate: %d", in_brate);
    lame_set_mode(lame, in_mode);
    LOGD("Mode: %d", in_mode);
    lame_set_quality(lame, in_quality);
    LOGD("Quality: %d", in_quality);

    int res = lame_init_params(lame);
    LOGD("Init returned: %d", res);
}

void Java_myPacakage_myApp_Record_destroyEncoder(
        JNIEnv *env, jobject jobj) {
    int res = lame_close(lame);
    LOGD("Deinit returned: %d", res);
}

void Java_myPacakage_myApp_Record_encodeFile(JNIEnv *env,
        jobject jobj, jstring in_source_path, jstring in_target_path) {
    const char *source_path, *target_path;
    source_path = (*env)->GetStringUTFChars(env, in_source_path, NULL);
    target_path = (*env)->GetStringUTFChars(env, in_target_path, NULL);

    FILE *input_file, *output_file;
    input_file = fopen(source_path, "rb");
    output_file = fopen(target_path, "wb");

    short input[BUFFER_SIZE];
    char output[BUFFER_SIZE];
    int nb_read = 0;
    int nb_write = 0;
    int nb_total = 0;

    LOGD("Encoding started");
    while (nb_read = read_samples(input_file, input)) {
        nb_write = lame_encode_buffer(lame, input, input, nb_read, output,
                BUFFER_SIZE);
        fwrite(output, nb_write, 1, output_file);
        nb_total += nb_write;
    }
    LOGD("Encoded %d bytes", nb_total);

    nb_write = lame_encode_flush(lame, output, BUFFER_SIZE);
    fwrite(output, nb_write, 1, output_file);
    LOGD("Flushed %d bytes", nb_write);

    fclose(input_file);
    fclose(output_file);
}

的修改的 - 确定，所以出于兴趣我下载教程提供的apk到我的手机并运行它。这工作正常。所以这个建议，问题是减配的教程和更多的东西我已经做到了。我会再看看在这个时候我有一些可用的时间，看看我能确定我在哪里出了错

Edit - ok so out of interest I downloaded the apk the tutorial provides to my phone and ran it. That works fine. So this would suggest the problem is less with the tutorial and more something I've done. I will re-look over this when I have some time available and see if I can determine where I went wrong

推荐答案

您拨打的 initEn codeR 是 2 渠道，并初始化 AudioRecord 与立体声和单声道，但wrapper.c只能处理1路：

You call initEncoder with 2 channels, and initialize AudioRecord with STEREO and MONO, but wrapper.c can only deal with 1 channel:

nb_write = lame_encode_buffer(lame, input, input, nb_read, output, BUFFER_SIZE);

以上codeS需要将源的音频单与1路。如果你想支持立体声，注意 lame_en code_buffer 方式

int CDECL lame_encode_buffer (                                                                                                                                
    lame_global_flags*  gfp,           /* global context handle         */                                                                                
    const short int     buffer_l [],   /* PCM data for left channel     */                                                                                
    const short int     buffer_r [],   /* PCM data for right channel    */                                                                                
    const int           nsamples,      /* number of samples per channel */                                                                                
    unsigned char*      mp3buf,        /* pointer to encoded MP3 stream */                                                                                
    const int           mp3buf_size ); /* number of valid octets in this                                                                                  
                                          stream                        */

这篇关于拉梅EN codeD MP3音频放缓 - Android电子的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！