无法使用 Android 版 VLC 设置字幕

启动 Android 版 VLC 的 VideoPlayerActivity 时，我在设置字幕位置时遇到问题。我的目标是 API 27 并使用 FileProvider 来允许访问文件。

根据文档here https://wiki.videolan.org/Android_Player_Intents#Extras_.28optional.29，如果您额外设置了“subtitles_location”，那么您可以提供字幕文件的路径。不幸的是，我似乎无法让它发挥作用。

我看到“字幕”菜单项保持灰色，下载字幕似乎不会改变这种状态。点击时，“选择字幕文件”VLC 表明目录中没有字幕文件，并且 URI 的前缀为“content://”。

视频文件和字幕文件共享相同的父目录，并使用 FileProvider 提供。

当目标 API >= 24 时，如何设置字幕文件？

Update:

• 似乎当点击字幕选择菜单项时，它使用 视频文件的父目录。这是在这里看到的。 https://code.videolan.org/videolan/vlc-android/blob/master/vlc-android/src/org/videolan/vlc/gui/video/VideoPlayerActivity.java#L2373
• 想通了，请看下面的解决方案。

下面是我如何通过意图启动 VideoPlayerActivity 的一些代码片段。

播放视频方法：

/**
 * Play a video using VLC media player. This method will play media by using
 * the VLC VideoPlayerActivity.
 *
 * @param activity         The current activity.
 * @param authority        The FileProvider authority.
 * @param vlcPackageName   The VLC package name.
 * @param vlcActivityName  The VLC activity name.
 * @param videoFile        The video file to play.
 * @param subtitlesFile    The subtitles file to play.
 * @param playbackPosition The playback position.
 * @param requestCode      The activity for result request code.
 */
public static void playVideo(
        AppCompatActivity activity,
        String authority,
        String vlcPackageName,
        String vlcActivityName,
        String vlcTitleExtra,
        String vlcPositionExtra,
        String vlcFromStartExtra,
        String vlcSubtitlesExtra,
        File videoFile,
        File subtitlesFile,
        long playbackPosition,
        int requestCode
) {
    Intent intent = new Intent(Intent.ACTION_VIEW);

    intent.setPackage(vlcPackageName);

    // Set component to VLC video player activity.
    intent.setComponent(new ComponentName(
            vlcPackageName,
            vlcActivityName
    ));

    // Set intent permission flags.
    intent.addFlags(Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION);
    intent.addFlags(Intent.FLAG_GRANT_PREFIX_URI_PERMISSION);
    intent.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
    intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);

    // Set title and playback position.
    intent.putExtra(vlcTitleExtra, videoFile.getName());
    intent.putExtra(vlcPositionExtra, playbackPosition);
    intent.putExtra(vlcFromStartExtra, false);

    // Set video file location
    intent.setDataAndTypeAndNormalize(
            FileProvider.getUriForFile(
                    activity,
                    authority,
                    videoFile
            ),
            "video/*"
    );

    // Subtitles file provided, set location on intent.
    if (subtitlesFile != null) {
        intent.putExtra(
                vlcSubtitlesExtra,
                FileProvider.getUriForFile(
                        activity,
                        authority,
                        subtitlesFile
                )
        );
    }

    activity.startActivityForResult(intent, requestCode);
}

清单中的提供者定义

   <provider
        android:name="android.support.v4.content.FileProvider"
        android:authorities="com.masterwok.bitcast.fileprovider"
        android:exported="false"
        android:grantUriPermissions="true" >
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/paths" />
    </provider>

@xml/paths 定义：

<?xml version="1.0" encoding="utf-8"?>
<paths>
    <external-path
        name="Download"
        path="Download/"/>
</paths>

我能够通过使用未记录的“item_location”额外定义来解决这个问题：here https://code.videolan.org/videolan/vlc-android/blob/master/vlc-android/src/org/videolan/vlc/util/Constants.java#L74.

当目标 API >= 24 时，这可以解决权限问题。发生的情况是 VideoPlayerActivity 试图读取使用 FileProvider 提供的 URI 的父目录。如果我不得不猜测的话，我会说 Android 不允许这样做。

通过使用额外的“item_location”传递 URI，我们可以绕过此限制。

我现在用来播放视频文件的方法如下：

/**
 * Play a video using VLC media player. This method will play media by using
 * the VLC VideoPlayerActivity.
 *
 * @param activity         The current activity.
 * @param vlcPackageName   The VLC package name.
 * @param vlcActivityName  The VLC activity name.
 * @param videoFile        The video file to play.
 * @param playbackPosition The playback position.
 * @param requestCode      The activity for result request code.
 */
public static void playVideo(
        AppCompatActivity activity,
        String vlcPackageName,
        String vlcActivityName,
        String vlcItemLocationExtra,
        String vlcTitleExtra,
        String vlcPositionExtra,
        String vlcFromStartExtra,
        File videoFile,
        long playbackPosition,
        int requestCode
) {
    Intent intent = new Intent(Intent.ACTION_VIEW);

    intent.setPackage(vlcPackageName);

    // Set component to VLC video player activity.
    intent.setComponent(new ComponentName(
            vlcPackageName,
            vlcActivityName
    ));

    // Set intent permission flags.
    intent.addFlags(Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION);
    intent.addFlags(Intent.FLAG_GRANT_PREFIX_URI_PERMISSION);
    intent.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
    intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);

    // Set title and playback position.
    intent.putExtra(vlcTitleExtra, videoFile.getName());
    intent.putExtra(vlcPositionExtra, playbackPosition);
    intent.putExtra(vlcFromStartExtra, false);

    // Set video file location (subtitles are found by VLC by using parent directory).
    intent.putExtra(vlcItemLocationExtra, Uri.fromFile(videoFile));

    activity.startActivityForResult(intent, requestCode);
}