By default KPlayer resizes the main window automatically unless it is maximized or full screen. When KPlayer loads and starts playing a new video, it scales it in increments of 50% of the original video size until the video width reaches the Minimum initial video width setting. It also automatically resizes the window to maintain the video aspect if that option is turned on.

If you would like to avoid automatic resizing and always keep the window the size you make it, turn this option off. KPlayer will then maintain the video aspect by constraining the video within the window, as if the window was maximized for example. You will also want to turn this option off if you get problems coming back from full screen mode, like endless flickering for example. But in that case you should also report the bug following instructions in the Reporting bugs micro-HOWTO.

These options control the size of playlist menus, the recent menu and the recent list in the multimedia library respectively. If the limits are exceeded, the menus will show the top items up to the limit you provide, and items from the Recent section of the library that exceed the limit will be removed.

KPlayer will remember the properties of any files or URLs it has played, even when they are removed from the multimedia library. It will only start forgetting old file properties after a large number of files have been played. This setting controls that number, by default it is 10000. This has nothing to do with MPlayer cache, look on the Advanced page for that.

By default KPlayer removes duplicate entries from playlists when adding new entries. Turning the option on allows you to have duplicate entries on playlists. Duplicate means that the entries' URLs are exactly the same. Note however that different playlist folders can have identical entries regardless of this setting.

When an error occurs while trying to play a file, KPlayer shows an Error indicator in the status bar. You can then left click the indicator to show the message log containing the full output from MPlayer and KDE I/O Slaves. When this option is turned on, KPlayer will show the message log automatically whenever an error occurs.

KPlayer 0.5 and later comes with the ability to set a good number of different options on a per file or URL basis. Those options are called file properties. The File properties micro-HOWTO has more information.

On this page you can choose the properties that will be remembered automatically for each file or URL. By default KPlayer remembers the video aspect ratio, audio delay and subtitle delay.

Alternatively, you can make KPlayer remember a setting for the current file by holding the Shift key while changing that setting. For example, if you have a video file that needs too much resources to play correctly on your system, you can hold the Shift key and choose a frame dropping setting from the Advanced submenu of the Player menu. KPlayer will then use that setting for this file only, and will continue using the default setting for all other files.

This option allows you to choose how much KPlayer will seek forward or backward when you use the seek commands on the Player menu. You can set the amounts in percentages of the video length or in seconds.

This is the amount by which a setting like volume or contrast will change when you use commands like Increase Volume or Decrease Contrast on the Player menu.

This option allows you to choose the video or audio output that MPlayer will use. The recommended outputs are XVideo for video and ALSA for audio.

For some output types you can also specify the device that MPlayer will use for output. For other output types this sets the output subtype instead. For still other output types this setting may not be meaningful at all. You can find the details on the MPlayer manpage.

This sets the preferred decoder and codec that MPlayer should use for decoding video or audio. This option is not of much use anymore since KPlayer 0.5 introduced file properties and the ability to set the codec for each file or URL individually.

When using a video output that does not support hardware scaling, like X11, this option sets the scaler type to use. Since normally you would use XVideo or another video output that supports hardware scaling, this option will have no effect. But if you use X11 output or otherwise enable software scaler, you can play around with this option to see what setting gives you the best results. Bicubic and bicubic spline are supposed to give smooth picture in most cases.

This option is enabled by default. It gives smoother video in most cases.

This option may give better performance. However, it will not work with double buffering, and also causes subtitles to be jerky. It is disabled by default.

This option tells MPlayer to use software volume control, which does not affect global volume settings on your system, but may result in some distortion of the sound. When this is enabled, the maximum volume level is controlled by the Maximum volume setting, which is in percent of the normal volume level.

These options let you choose an ALSA or OSS device and channel that will be used to control the sound volume. These options are not available when the software volume option above is enabled.

This option and a similar one for subtitles gives the amount by which the delay of audio or subtitles relative to video will be changed when using the Increase Delay and Decrease Delay commands on the Audio or Subtitles submenu of the Player menu or the corresponding keyboard shortcuts.

In this field you can place additional command line options you want to pass to MPlayer. For example, to get more informational output in the message log, put the -v option in this field. You can add more options for an individual file or URL in its file properties.

This sets the preferred demultiplexer that MPlayer should use for decoding files and streams. You can also choose a demuxer for each individual file or stream in its file properties. For example you can choose the lavf option if the libavformat demuxer works better for your multimedia than other MPlayer demuxers.

If your system is too slow to play your files properly, this option will tell MPlayer to drop some frames. You can also set the frame dropping option on a per file or URL basis. Just hold down the Shift key when selecting a frame dropping option from the Advanced submenu of the Player menu, and KPlayer will remember it for the current file or URL. If you need frame dropping, try the soft option first.

This is probably the most tricky of MPlayer options. It is especially important when playing directly from a KDE I/O Slave. Although most audio files will play fine with only 64 kilobyte cache, such a small cache will cause problems with many video files. Also, some slow media types like DVD, VCD, NFS, Samba, etc. may sometimes require much larger cache like eight megabytes. On the other hand, low bitrate media like online radio stations may need smaller cache so they start playing more quickly. Also, according to MPlayer crashing message, non-interleaved AVI files may need cache to be turned off. As usual, you can set the Cache option for each individual file or URL in its file properties.

If a file does not have an index or has a broken one, so seeking is not functional, you can try setting this option to see if it gives an improvement. Turning it on usually does not hurt, but the force setting should only be set in the properties of an individual file or URL.

This option will only have effect when using a KDE I/O Slave. By default it is turned off, so data is sent to MPlayer through a named pipe. This works most of the time, the only disadvantage being that seeking is not possible and the time length will usually be unknown. If playing directly from a KDE I/O Slave does not work for you, turn this option on. Then KPlayer will download and save the file locally before playing it. This will take more time and also take up some disk space temporarily, but it will make length detection and seeking possible. This option is also available in file properties, so you can change it for individual files and URLs.

Those three URL types can be played either directly by MPlayer or using a KDE I/O Slave. All three options are turned off by default, so the URLs are passed to MPlayer directly. But if that does not work for any reason, you will want to turn the corresponding option on, so that KPlayer uses the I/O Slave. You can also set this option in the individual file properties.