[移动开发]Android播放视频快进帧预览图完美解決方案

播放视频快进预览图完美解決方案，使用方法如下，使用FFmpeg，不影响原有播放器，

就是先截取缩略图保存下来，快进时选用图片显示，最优方案，播放性能最好，体验完美。

参考github:

https://github.com/wseemann/FFmpegMediaMetadataRetriever

下载jar

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解压之后拷贝如下两个aar到项目libs目录下

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使用方法：

FFmpegMediaMetadataRetriever mmr = new FFmpegMediaMetadataRetriever();

mmr.setDataSource(mUri);

mmr.extractMetadata(FFmpegMediaMetadataRetriever.METADATA_KEY_ALBUM);

mmr.extractMetadata(FFmpegMediaMetadataRetriever.METADATA_KEY_ARTIST);

Bitmap b = mmr.getFrameAtTime(2000000, FFmpegMediaMetadataRetriever.OPTION_CLOSEST); // frame at 2 seconds

byte [] artwork = mmr.getEmbeddedPicture();

mmr.release();

代码：

package com.tianci.player.preview;

import android.graphics.Bitmap;
import android.net.Uri;
import android.widget.ImageView;
import com.tianci.localmedia.util.SkyLocalContext;
import com.tianci.utils.MediaLogUtils;
import com.tianci.utils.Utils;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import wseemann.media.FFmpegMediaMetadataRetriever;

public class PreviewImageUtils {
    private static FFmpegMediaMetadataRetriever ffmmr = null;
    private static final String savePath = SkyLocalContext.getContext().getCacheDir().getPath() + "/preview/";
    private String filePath = null;
    private String fileName = null;
    private boolean isStop = false;
    private int mDuration = 0;
    private String outDir = null;

    private static PreviewImageUtils mInstance;

    public static PreviewImageUtils getInstance()
    {
        if (null == mInstance)
        {
            synchronized (PreviewImageUtils.class)
            {
                if (null==mInstance)
                {
                    mInstance = new PreviewImageUtils();
                }
            }
        }
        return mInstance;
    }

    public PreviewImageUtils()
    {

    }

    private void getDuration(String url)
    {
        try{
            if (ffmmr!=null)
            {
                ffmmr.release();
                ffmmr = null;
            }
            ffmmr =new FFmpegMediaMetadataRetriever();
            ffmmr.setDataSource(url);
            String durationStr = ffmmr.extractMetadata(FFmpegMediaMetadataRetriever.METADATA_KEY_DURATION);
            mDuration = Integer.parseInt(durationStr)/1000;
            ffmmr.release();
            ffmmr = null;

        }catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    public void startDecode(String oldUrl, String url)
    {
        Bitmap bitmap = null;
        filePath = url;
        isStop = false;
        getDuration(url);
        MediaLogUtils.d("startDecode-----------------url:"+url);
        File file = new File(url);
        if (file!=null&&file.exists())
        {
            fileName = file.getName();
        }else {
            return;
        }
        deleteBitmap(oldUrl);
        try {
            getFrameAtTime(url, mDuration, 50);
            getFrameAtTime(url, mDuration, 30);
            getFrameAtTime(url, mDuration, 20);
            getFrameAtTime(url, mDuration, 10);
            getFrameAtTime(url, mDuration, 5);
            getFrameAtTime(url, mDuration, 3);
            MediaLogUtils.d("startDecode------end-----------mDuration:"+mDuration);
        }catch (Exception e)
        {
            e.printStackTrace();
            ffmmr = null;
        }
    }

    private void getFrameAtTime(String url, int duration, int step)
    {
        Bitmap bitmap = null;
        try {
            if (ffmmr!=null)
            {
                ffmmr.release();
                ffmmr = null;
            }
            ffmmr =new FFmpegMediaMetadataRetriever();
            ffmmr.setDataSource(url);
            for (int i=0; i< duration; i+=step)
            {
                int pos = i*1000*1000;
                if (hasFile(i, fileName))
                {
                    continue;
                }
                if (ffmmr!=null)
                {
                    bitmap = ffmmr.getScaledFrameAtTime(pos, 160, 90);
                    if (bitmap!=null)
                        saveBitmap(bitmap, i, fileName);
                }
                Thread.sleep(10);
                if (isStop)
                {
                    break;
                }
            }
            ffmmr.release();
            ffmmr = null;
        }catch (Exception e)
        {
            e.printStackTrace();
        }
    }



    private void  deleteFile(String path) {
        MediaLogUtils.d("deleteFile-----------------path:"+path);
        File file=new File(path);
        if (file!=null&&!file.exists())
        {
            MediaLogUtils.d("空目录");
            return;
        }
        try
        {
            File[] files=file.listFiles();
            if (files == null){
                MediaLogUtils.d("空目录");
                return;
            }
            for(int i =0;i<files.length;i++){
                files[i].delete();
            }
        }catch (Exception e)
        {
            e.printStackTrace();
        }

    }

    public void setStop(Boolean stop)
    {
        isStop = stop;
    }

    private void deleteBitmap(String path)
    {
        try {

            File file = new File(path);
            if (file.exists())
            {
                String deleteDir = savePath + file.getName();
                deleteFile(deleteDir);
            }
        }catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    private synchronized void saveBitmap(Bitmap bitmap , int position, String name) {
        outDir = savePath+name;
        try {
            File dirFile = new File(outDir);
            if (!dirFile.exists()) {              //如果不存在，那就建立这个文件夹
                dirFile.mkdirs();
                dirFile.setWritable(true);
                dirFile.setReadable(true);
                Runtime.getRuntime().exec("chmod 777 -R " + dirFile.getAbsolutePath());
            }
            File file = new File(outDir,  position+".jpg");

            FileOutputStream fos = new FileOutputStream(file);
            bitmap.compress(Bitmap.CompressFormat.JPEG, 80, fos);
            if (file.exists())
            {
                file.setWritable(true);
                file.setReadable(true);
                Runtime.getRuntime().exec("chmod 777 -R " + file.getAbsolutePath());
            }
            fos.flush();
            fos.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public static synchronized void setPreview(ImageView imageView, String url, int position)
    {
        MediaLogUtils.d("setPreview()--------------url:"+url);
        MediaLogUtils.d("setPreview()--------------position:"+position);
        String previewPath = null;
        String name = null;
        File file = new File(url);
        if (file.exists())
        {
            name = file.getName();
        }
        previewPath = savePath+name+"/"+position+".jpg";

        File showPicFile = new File(previewPath);
        if (showPicFile!=null&&showPicFile.exists())
        {
            Uri uri = Uri.parse(previewPath);
            imageView.setImageURI(uri);
        }
    }

    private boolean hasFile(int position, String name)
    {
        try {
            String filePath = savePath+name+"/"+position+".jpg";
            File file = new File(filePath);
            if (file!=null&&file.exists())
            {
                return true;
            }
        }catch (Exception e)
        {
            e.printStackTrace();
        }

        return false;
    }
}

在播放器起播的时候使用

PreviewImageUtils.getInstance().setStop(true);
PreviewImageUtils.getInstance().startDecode(null, url);

效果图：

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