Smacker video
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| Filename extension | .smk |
|---|---|
| Type code | Smk2 |
| Developed by | RAD Game Tools |
| Type of format | Video codec |
| Container for | Smacker |
Smacker video is a video file format (with the .SMK file extension) developed by RAD Game Tools, and primarily used for full-motion video in video games. Smacker uses an adaptive 8-bit RGB palette. RAD's format for video at higher color depths is Bink Video. The Smacker format specifies a container format, a video compression format, and an audio compression format. Since its release in 1994, Smacker has been used in over 2300 games. Blizzard used this format for the cinematic videos seen in its games Warcraft II, StarCraft and Diablo I.
The format has been reverse engineered and implemented in libavcodec. A non-commercial SourceForge project libsmacker released an open source decoder in 2013.
Smacker defines its own container format. A Smacker file can contain a Smacker video track and up to seven audio tracks. Each audio track can have either one channel (mono) or two channels (stereo) with a bit depth of either 8-bit or 16-bit. The audio can either be uncompressed PCM, compressed in the Smacker Audio format, or, in newer versions of Smacker, compressed in the Bink Audio format.
Smacker video supports 256 colors, and includes transparency support. While being a palette-based format, which is inherently limited to having not more than 256 colors in each frame, Smacker videos may still contain more colors in total due to "palette rotation", whereby the palette is updated on a per-frame basis. This usually results in SMK files that look better if the source video has more than 256 colors. The compression rate of Smacker can reach 1:12, but at the loss of quality (pixelation).
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