src/windows/MediaProxy.js
function fullPathToAppData(uri) {
    if (uri.schemeName === 'file') {
        if (uri.rawUri.indexOf(Windows.Storage.ApplicationData.current.localFolder.path) !== -1) {
            // Also remove path' beginning slash to avoid losing folder name part
            uri = new Windows.Foundation.Uri(localFolderAppDataBasePath, uri.rawUri.replace(localFolderFullPath, '').replace(/^[\\\/]{1,2}/, ''));
        } else if (uri.rawUri.indexOf(Windows.Storage.ApplicationData.current.temporaryFolder.path) !== -1) {
            uri = new Windows.Foundation.Uri(tempFolderAppDataBasePath, uri.rawUri.replace(tempFolderFullPath, '').replace(/^[\\\/]{1,2}/, ''));
        } else {
            throw new Error('Not supported file uri: ' + uri.rawUri);
        }
    }

    return uri;
}
function fullPathToAppData(uri) {
    if (uri.schemeName === 'file') {
        if (uri.rawUri.indexOf(Windows.Storage.ApplicationData.current.localFolder.path) !== -1) {
            // Also remove path' beginning slash to avoid losing folder name part
            uri = new Windows.Foundation.Uri(localFolderAppDataBasePath, uri.rawUri.replace(localFolderFullPath, '').replace(/^[\\\/]{1,2}/, ''));
        } else if (uri.rawUri.indexOf(Windows.Storage.ApplicationData.current.temporaryFolder.path) !== -1) {
            uri = new Windows.Foundation.Uri(tempFolderAppDataBasePath, uri.rawUri.replace(tempFolderFullPath, '').replace(/^[\\\/]{1,2}/, ''));
        } else {
            throw new Error('Not supported file uri: ' + uri.rawUri);
        }
    }

    return uri;
}
Convert native full path to ms-appdata path
@param  {Object} uri Windows.Foundation.Uri
@return {Object}     ms-appdata Windows.Foundation.Uri