Question

我正在使用存储在SD卡中的视频创建缩略图，在网格视图中显示缩略图及其名称。在网格视图的项目选定事件上弹出一个对话框，询问x，y，右，底部位置，然后将其粘贴到主活动。我收到了视频文件，并试图使用媒体商店创建缩略图也检索缩略图作为位图，但位图为空。在网格视图中显示视频名称，我可以选择相应的缩略图，并且可以给出位置，也可以将缩略图设置为主要活动。问题是位图为空并且位图图像未显示（文本视频名称显示）。有什么问题？我弄清楚了吗？ Plz帮帮我？我的代码如下。提前谢谢。

      if (f.isFile()) {
      if (fName.endsWith(".mpg")
    || fName.endsWith(".mov")
    || fName.endsWith(".wmv")
    || fName.endsWith(".rm")
    || fName.endsWith(".mp4")) {
    tv.setText(fName);
    path = f.getAbsolutePath();
    System.out.println("Video file path=>"+path);


 thumb = ThumbnailUtils.createVideoThumbnail(f.getAbsolutePath(),MediaStore.Video.Thumbnails.MICRO_KIND);


    if(thumb==null)
      {
         /**Every time it printing null**/
         System.out.println("Thumb is null");

      }
      iv.setImageBitmap(thumb);

Answer 1

来自ThumbnailUtils.createVideoThumbnail文档：May return null if the video is corrupt or the format is not supported.

默认情况下，几乎所有支持的格式都是mp4和3gp。请参阅此处：http://developer.android.com/guide/appendix/media-formats.html以获取默认支持的媒体格式的完整列表。

Answer 2

如果您要从SD卡视频创建缩略图，则会创建ThumbnailUtils.createVideoThumbnail，否则请使用光标。

See this example

Answer 3

Try this code. It is getting the thumbnail of videos from urls. instead of pass the path of sd card .it will help you . Dont forgot to add internet permission in manifest file.
public class VideoThumbnailActivity extends Activity {

    public static final String Downloader = null;
    static String uri1="http://daily3gp.com/vids/lucky_guy.3gp";
    static String uri2="http://daily3gp.com/vids/reporter_hit_by_plane.3gp";
    static String uri3="http://daily3gp.com/vids/motorcycle_wipesout_explodes.3gp";
    static String uri4="http://commonsware.com/misc/test2.3gp";
    public static  String uri_array[]={uri1,uri2,uri3,uri4,uri1,uri2,uri3,uri4,uri1,uri2,uri3,uri4};


    ImageView imageView;
    String url;
    Gallery ga1,ga2;

    /** Called when the activity is first created. */
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        imageView = (ImageView)findViewById(R.id.imageView);
        ga1 = (Gallery)findViewById(R.id.gallery1);
        ga1.setAdapter(new ImageAdapter(getApplicationContext()));
        imageView.setImageBitmap(ThumbnailUtils.createVideoThumbnail(uri_array[0], MediaStore.Video.Thumbnails.FULL_SCREEN_KIND));

        //on click event on gallery
        ga1.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View view, final int position,long arg3) {
             imageView.setImageBitmap(ThumbnailUtils.createVideoThumbnail(uri_array[position], MediaStore.Video.Thumbnails.FULL_SCREEN_KIND));

             //on click event on imageview to play video
             imageView.setOnClickListener(new OnClickListener() {

                            @Override
                            public void onClick(View view) {
                                // TODO Auto-generated method stub
                                Intent intent = new Intent(getApplicationContext(),PlayActivity.class);
                                intent.putExtra("path",uri_array[position]);
                                startActivity(intent);
                            }
                        });

                        }

                });

            }

            public class ImageAdapter extends BaseAdapter {

                private Context ctx;
                int imageBackground;

                public ImageAdapter(Context c) {
                    ctx = c;
                    TypedArray ta = obtainStyledAttributes(R.styleable.Gallery1);
                    imageBackground = ta.getResourceId(R.styleable.Gallery1_android_galleryItemBackground, 1);
                    ta.recycle();
                }

                @Override
                public int getCount() {

                    return uri_array.length;

                }

                @Override
                public Object getItem(int arg0) {

                    return arg0;
                }

                @Override
                public long getItemId(int arg0) {

                    return arg0;
                }

                @Override
                public View getView(int position, View view, ViewGroup arg2) {

                    ImageView iv = new ImageView(ctx);
                    Bitmap curThumb = null;
                    curThumb = ThumbnailUtils.createVideoThumbnail(uri_array[position],MediaStore.Video.Thumbnails.FULL_SCREEN_KIND);
                    iv.setImageBitmap(curThumb);
                    iv.setScaleType(ImageView.ScaleType.FIT_XY);
                    iv.setLayoutParams(new Gallery.LayoutParams(150,120));
                    iv.setBackgroundResource(imageBackground);
                    return iv;
            }
        }

让我知道您的问题是否得到解决。

视频缩略图返回null

3 个答案: