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"];

Start by reproducing the severe stuttering with local and remote 4K MP4 files on iOS using the listed player and format options, especially VideoToolbox-related settings. Compare behavior across the supplied 2 Mbps and 5 Mbps cases; done means smooth playback under those conditions or a documented, reproducible diagnosis.

Written by the indexing model from the issue text.