iOS 播放4k分辨率mp4视频(2Mbps、5Mbps)，无论本地和远程均会出现严重卡顿，option配置如下：

`[options setPlayerOptionIntValue:30 forKey:@"max-fps"];
[options setPlayerOptionIntValue:0 forKey:@"framedrop"];
[options setPlayerOptionIntValue:3 forKey:@"video-pictq-size"];
[options setPlayerOptionIntValue:960 forKey:@"videotoolbox-max-frame-width"];
[options setFormatOptionIntValue:0 forKey:@"auto_convert"];
[options setFormatOptionIntValue:1 forKey:@"reconnect"];
[options setFormatOptionIntValue:30 * 1000 * 1000 forKey:@"timeout"];
[options setFormatOptionValue:@"ijkplayer" forKey:@"user-agent"];
[options setPlayerOptionIntValue:31457280 forKey:@"max-buffer-size"];
[options setPlayerOptionIntValue:0 forKey:@"infbuf"];
[options setPlayerOptionIntValue:1 forKey:@"packet-buffering"];
[options setPlayerOptionIntValue:1 forKey:@"videotoolbox"];`

No source file, entry point, or test is named. Start by reproducing the severe stuttering with the supplied options on iOS using the reported local and remote 4K MP4 cases, then trace the playback and VideoToolbox paths. Done means determining the cause and confirming smooth playback for both cases.

Written by the indexing model from the issue text.