Android中使用 MediaExtractor 和 MediaMuxer解析、封装 mp4 文件

最近开始学习Android下的封装和解封装技术，熟悉MediaExtractor和MediaMuxer的使用。

1、MainActivity.java文件：

package com.example.tongjiangsong.mediaextractmuxer;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    private Button button;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (Button)findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new ExtractorMuxerThread().start();
            }
        });
    }
}

2、ExtractorMuxerThread.java文件：

package com.example.tongjiangsong.mediaextractmuxer;

import android.media.MediaCodec;
import android.media.MediaExtractor;
import android.media.MediaFormat;
import android.media.MediaMuxer;
import android.os.Environment;
import android.widget.Toast;

import java.io.IOException;
import java.nio.ByteBuffer;
import android.view.View;

public class ExtractorMuxerThread extends Thread {
    @Override
    public void run() {
        super.run();
        mixer();
    }
    public void mixer() {
        MediaExtractor videoExtractor = null;
        MediaExtractor audioExtractor = null;
        MediaMuxer mixMediaMuxer = null;
        String outputVideoFilePath = Environment.getExternalStorageDirectory().getAbsolutePath()+"/people.mp4";
        String outputAudioFilePath = Environment.getExternalStorageDirectory().getAbsolutePath()+"/qishi.aac";
        String outputFilePath = Environment.getExternalStorageDirectory().getAbsolutePath()+"/mixer.mp4";

        try {
            videoExtractor = new MediaExtractor();
            videoExtractor.setDataSource(outputVideoFilePath);
            int videoIndex = -1;
            MediaFormat videoTrackFormat = null;
            int trackCount = videoExtractor.getTrackCount();
            for (int i = 0; i < trackCount; i++) {
                videoTrackFormat = videoExtractor.getTrackFormat(i);
                if (videoTrackFormat.getString(MediaFormat.KEY_MIME).startsWith("video/")) {
                    videoIndex = i;
                    break;
                }
            }

            audioExtractor = new MediaExtractor();
            audioExtractor.setDataSource(outputAudioFilePath);
            int audioIndex = -1;
            MediaFormat audioTrackFormat = null;
            trackCount = audioExtractor.getTrackCount();
            for (int i = 0; i < trackCount; i++) {
                audioTrackFormat = audioExtractor.getTrackFormat(i);
                if (audioTrackFormat.getString(MediaFormat.KEY_MIME).startsWith("audio/")) {
                    audioIndex = i;
                    break;
                }
            }

            videoExtractor.selectTrack(videoIndex);
            audioExtractor.selectTrack(audioIndex);

            MediaCodec.BufferInfo videoBufferInfo = new MediaCodec.BufferInfo();
            MediaCodec.BufferInfo audioBufferInfo = new MediaCodec.BufferInfo();

            mixMediaMuxer = new MediaMuxer(outputFilePath, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
            int videoTrackIndex = mixMediaMuxer.addTrack(videoTrackFormat);
            int audioTrackIndex = mixMediaMuxer.addTrack(audioTrackFormat);

            mixMediaMuxer.start();

            ByteBuffer byteBuffer = ByteBuffer.allocate(1024 * 1024);
            long videotime;
            long audiotime;

            {
                videoExtractor.readSampleData(byteBuffer, 0);
                if (videoExtractor.getSampleFlags() == MediaExtractor.SAMPLE_FLAG_SYNC) {
                    videoExtractor.advance();
                }
                videoExtractor.readSampleData(byteBuffer, 0);
                long sampleTime = videoExtractor.getSampleTime();
                videoExtractor.advance();
                videoExtractor.readSampleData(byteBuffer, 0);
                long sampleTime1 = videoExtractor.getSampleTime();
                videoExtractor.advance();
                videotime = Math.abs(sampleTime - sampleTime1);
            }

            {
                audioExtractor.readSampleData(byteBuffer, 0);
                if (audioExtractor.getSampleFlags() == MediaExtractor.SAMPLE_FLAG_SYNC) {
                    audioExtractor.advance();
                }
                audioExtractor.readSampleData(byteBuffer, 0);
                long sampleTime = audioExtractor.getSampleTime();
                audioExtractor.advance();
                audioExtractor.readSampleData(byteBuffer, 0);
                long sampleTime1 = audioExtractor.getSampleTime();
                audioExtractor.advance();

                audiotime = Math.abs(sampleTime - sampleTime1);
            }

            videoExtractor.unselectTrack(videoIndex);
            videoExtractor.selectTrack(videoIndex);

            while (true) {
                int data = videoExtractor.readSampleData(byteBuffer, 0);
                if (data < 0) {
                    break;
                }
                videoBufferInfo.size = data;
                videoBufferInfo.presentationTimeUs += videotime;
                videoBufferInfo.offset = 0;
                videoBufferInfo.flags = videoExtractor.getSampleFlags();

                mixMediaMuxer.writeSampleData(videoTrackIndex, byteBuffer, videoBufferInfo);
                videoExtractor.advance();
            }

            while (true) {
                int data = audioExtractor.readSampleData(byteBuffer, 0);
                if (data < 0) {
                    break;
                }
                audioBufferInfo.size = data;
                audioBufferInfo.presentationTimeUs += audiotime;
                audioBufferInfo.offset = 0;
                audioBufferInfo.flags = audioExtractor.getSampleFlags();

                mixMediaMuxer.writeSampleData(audioTrackIndex, byteBuffer, audioBufferInfo);
                audioExtractor.advance();
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (mixMediaMuxer != null) {
                mixMediaMuxer.stop();
                mixMediaMuxer.release();
            }
            if (videoExtractor != null){
                videoExtractor.release();
            }
            if (audioExtractor != null){
                audioExtractor.release();
            }
        }
    }
}

3、activity_main.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="解封装和封装!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

4、权限：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

5、运行结果：