ThumbnailUtils.createVideoThumbnail returns null for existing mp4 video

问题

I have a video and I need get its thumbnail. I use ThumbnailUtils class for this purpose, but it returns null instead of expected Bitmap. When I debug my app, I see that inside createVideoThumbnail method MediaMetadataRetriever.setDataSource invokes and it throws IllegalArgumentException. Inside setDataSource I see this code:

public void setDataSource(String path) throws IllegalArgumentException {
    if (path == null) {
        throw new IllegalArgumentException();
    }

    try (FileInputStream is = new FileInputStream(path)) {
        FileDescriptor fd = is.getFD();
        setDataSource(fd, 0, 0x7ffffffffffffffL);
    } catch (FileNotFoundException fileEx) {
        throw new IllegalArgumentException(); // and I've found out that method throws IllegalArgimentException inside this catch block
    } catch (IOException ioEx) {
        throw new IllegalArgumentException();
    }
}

I think it means that file with given file doesn't exist. But I see it in file system and it plays fine. Maybe there's another reason?

回答1:

The question is what you're passing to that method and from what you're obtaining it?

Below is the way I am doing this, and this works for me, so it should work for you as well.

File videoFile = new File(selectedVideoPath);

Bitmap bitmap = ThumbnailUtils.createVideoThumbnail(videoFile.getAbsolutePath(), MediaStore.Video.Thumbnails.FULL_SCREEN_KIND);

To get selectedVideoPath you should use https://github.com/iPaulPro/aFileChooser/blob/master/aFileChooser/src/com/ipaulpro/afilechooser/utils/FileUtils.java#L257 getPath(Context context, Uri uri) method. Originally it looked like:

public static String getPath(final Context context, final Uri uri) {

    if (DEBUG)
        Log.d(TAG + " File -",
                "Authority: " + uri.getAuthority() +
                        ", Fragment: " + uri.getFragment() +
                        ", Port: " + uri.getPort() +
                        ", Query: " + uri.getQuery() +
                        ", Scheme: " + uri.getScheme() +
                        ", Host: " + uri.getHost() +
                        ", Segments: " + uri.getPathSegments().toString()
                );

    final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;

    // DocumentProvider
    if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
        // LocalStorageProvider
        if (isLocalStorageDocument(uri)) {
            // The path is the id
            return DocumentsContract.getDocumentId(uri);
        }
        // ExternalStorageProvider
        else if (isExternalStorageDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];

            if ("primary".equalsIgnoreCase(type)) {
                return Environment.getExternalStorageDirectory() + "/" + split[1];
            }

            // TODO handle non-primary volumes
        }
        // DownloadsProvider
        else if (isDownloadsDocument(uri)) {

            final String id = DocumentsContract.getDocumentId(uri);
            final Uri contentUri = ContentUris.withAppendedId(
                    Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));

            return getDataColumn(context, contentUri, null, null);
        }
        // MediaProvider
        else if (isMediaDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];

            Uri contentUri = null;
            if ("image".equals(type)) {
                contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
            } else if ("video".equals(type)) {
                contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
            } else if ("audio".equals(type)) {
                contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
            }

            final String selection = "_id=?";
            final String[] selectionArgs = new String[] {
                    split[1]
            };

            return getDataColumn(context, contentUri, selection, selectionArgs);
        }
    }
    // MediaStore (and general)
    else if ("content".equalsIgnoreCase(uri.getScheme())) {

        // Return the remote address
        if (isGooglePhotosUri(uri))
            return uri.getLastPathSegment();

        return getDataColumn(context, uri, null, null);
    }
    // File
    else if ("file".equalsIgnoreCase(uri.getScheme())) {
        return uri.getPath();
    }

    return null;
}

Additionally you can add checking if videoFile exists by calling videoFile.exists().

Additionally if you're trying to read from external storage you can check if you have included READ_EXTERNAL_STORAGE permission in Manifest file, and if you're saving file and trying to get it thumbnail you should also need WRITE_EXTERNAL_STORAGE permission.

回答2:

There two reason behind the null for create a thumbnail of a video. either video is corrupt or the format is not supported to ThumbnailUtils.

Double check your file format and use the below code for thumbnail

// Create VideoThumbnail from sdcard path like this.

Bitmap thumb = ThumbnailUtils.createVideoThumbnail(filePath, Thumbnails.MINI_KIND);

来源：https://stackoverflow.com/questions/41377129/thumbnailutils-createvideothumbnail-returns-null-for-existing-mp4-video