Recording videos with DOSBox

Since version 0.65, DOSBox has the capability to record videos of the games you play. If you’re not familiar with DOSBox, you might want to start with the general DOSBox tutorial instead. This chapter explains how capturing videos works.

Basically, it’s quite simple: When you run DOSBox, just press CTRL-ALT-F5 to start recording. To stop it, press CTRL-ALT-F5 again. After that, you’ll find one or more AVI video files in your capture folder.

DOSBox uses its own lossless video codec to encode these videos, the ZMBV (Zip Motion Block Video) codec. It’s fast and has been designed for use with old games in low colors. On Windows, there is an installer shipped with DOSBox in order to be able to play your videos. On other systems, MPlayer, VLC and any other FFmpeg-based video player supports it.

DOSBox always encodes to the resolution and frame rate that the game currently uses. So, if a game switches screen modes in a session (for example between the menu and the actual game), you’ll have multiple video files then. A single file can’t hold multiple resolutions. So, you might want to transcode them to a more common video format using a specific resolution and frame rate.

Tips

  • If you play with non-fixed CPU cycles, the frame rate might drop depending on how fast your machine is. So, it’s better to set it to a fixed value to ensure a constant performance. You even could set it higher than your machine can handle in realtime, it will appear perfectly normal in the resulting videos.
  • Make sure your audio volume is not too high, otherwise the sounds might clip and lower the audio quality. Clipping means the audio signal is higher than the maximum value, so it will be cut with an unwanted noise as a result. Many games offer an option to change the volume, but you could also use the mixer command.
  • Most people might want to encode their final videos to 30 fps. However, DOSBox records them using the frequency of the current video mode, mostly about 70 or 50 Hz. So, if you transcode the frame rate afterwards, it will get somehow choppy in most cases. If you’re familiar with compiling software yourself, you could patch DOSBox to use 60 Hz. But keep in mind that games that depend on the frequency could have some trouble then, since they don’t expect that. Most games are fine, though.
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