Android获取视频第一帧 first frame 的研究之路

现在大大小小的应用都包含视频，原来的做法就是想办法利用前台的一张图片作为封面，今天终于不用这个图片啦。
研究路线:
一。根据stackoverflow搜索结果，测试第一帧。(这个方法不行)
地址

If you use API level 8 and above. You can create preview of a video like this:

String videoFile = "/sdcard/blonde.mp4";
Bitmap thumbnail = ThumbnailUtils.createVideoThumbnail(videoFile,
MediaStore.Images.Thumbnails.MINI_KIND);

If you use API level 8 and above. You can create preview of a video like this:

String videoFile = "/sdcard/blonde.mp4";
Bitmap thumbnail = ThumbnailUtils.createVideoThumbnail(videoFile,
MediaStore.Images.Thumbnails.MINI_KIND);
Now you can show it in an ImageView:

ImageView imageView = (ImageView) findViewById(R.id.my_image_view);
imageView.setImageBitmap(thumbnail);

Or you can set it to a VideoView as a background, so that it is shown as a first video frame before the video starts playing:

VideoView video = (VideoView) findViewById(R.id.my_video_view);
BitmapDrawable bitmapDrawable = new BitmapDrawable(thumbnail);
video.setBackgroundDrawable(bitmapDrawable);

二.亲测可用（支持本地本件，也可以是网络地址的多媒体文件）
1.添加依赖

    //获取第一帧的library
    implementation 'com.github.wseemann:FFmpegMediaMetadataRetriever:1.0.14'

2.添加读取存储卡的权限，现在很多框架不多说啦

3.最关键代码：

                    FFmpegMediaMetadataRetriever retriever = new  FFmpegMediaMetadataRetriever();
                    try {
//                        retriever.setDataSource("/storage/emulated/0/test.mp4"); //file's path
                        retriever.setDataSource("http://xyj.xueyijia.com.cn//2018/7/14/%E6%89%93%E9%A2%86%E5%B8%A6%E7%9A%84%E7%8B%90%E7%8B%B8%E5%B0%BC%E5%85%8B_2018_08_14_19_02_52.mp4"); //file's path
                        Bitmap bitmap = retriever.getFrameAtTime(100000,FFmpegMediaMetadataRetriever.OPTION_CLOSEST_SYNC );  //这个时间就是第一秒的
                        Drawable drawable = new BitmapDrawable(getResources(), bitmap);
                        Glide.with(mContext).load(drawable).into(ivFrame);

                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    finally{
                        retriever.release();
                    }

4.over