Bink Container

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This page is based on the document 'Description of the Bink File Format' by Mike Melanson at

Bink files are multimedia files used in a variety of video games, both on personal computers platforms and video game consoles. The files act as containers for data compressed with the proprietary Bink video, Bink video 2 and audio codecs. Bink multimedia files are known to bear the .bik, .bk2 or .bik2 extension.

File Format

This description is known to be incomplete.

All multi-byte numbers are stored in little endian format.

Bink files commence with a 44-byte header which is laid out as follows. Audio information follows the main header. If there are zero audio tracks, then the headers are omitted.

 bytes 0-2     file signature ('BIK', or 'KB2' for Bink Video 2)
 byte 3        Bink Video codec revision (0x62, 0x64, 0x66, 0x67, 0x68, 0x69; b,d,f,g,h,i respectively)
               Bink Video 2 codec revision ('a', 'd', 'f', 'g', 'h', 'i')
 bytes 4-7     file size not including the first 8 bytes
 bytes 8-11    number of frames
 bytes 12-15   largest frame size in bytes
 bytes 16-19   number of frames again?
 bytes 20-23   video width (less than or equal to 32767)
 bytes 24-27   video height (less than or equal to 32767)
 bytes 28-31   video frames per second dividend
 bytes 32-35   video frames per second divider
 bytes 36-39   video flags
                  bits 28-31: width and height scaling
                    1 = 2x height doubled
                    2 = 2x height interlaced
                    3 = 2x width doubled
                    4 = 2x width and height-doubled
                    5 = 2x width and height-interlaced
                  bit 20: has alpha plane
                  bit 17: grayscale
 bytes 40-43   number of audio tracks (less than or equal to 256)
 for each audio track
    two bytes   unknown
    two bytes   audio channels (1 or 2). Not authoritative, see flags below.
 for each audio track
    two bytes   audio sample rate (Hz)
    two bytes   flags
                  bit 15: unknown (observed in some samples)
                  bit 14: unknown (observed in some samples)
                  bit 13: stereo flag
                  bit 12: Bink Audio algorithm
                    1 = use Bink Audio DCT 
                    0 = use Bink Audio FFT
 for each audio track
    four bytes  audio track ID

Bink Video revisions f and g contain video planes in YVU order, while the planes are ordered YUV in other (later) revisions. Revision b is found in Heroes of Might and Magic 3, but is not supported by any of the tools published by RAD Game Tools.

Bink Video 2 revision a is found in Gears of War 3 (Xbox 360) . Revision d is found in WWE `13 (Xbox 360). Neither are currently supported by the tools published by RAD Game Tools.

The audio track flags are similar to those defined for the Smacker AudioRate flags.

Following the header is a frame index table. The number of entries in the table is equal to the number of frames specified in the header plus one. Each entry consists of a 32-bit absolute offset for that frame. There is no length information provided in the table, so the length of a sample is implicitly the difference between frame offsets, and the size of the file (for the very last frame). If bit 0 of an entry is set, that frame is a keyframe; this bit should be masked off to find the actual offset of the frame data in the file. The final frame offset is equal to the size of the entire file (likely included to simplify calculation of the length of the final frame).

Each frame contains (optional) audio and video data. Bytes 12-15 (largest frame size) probably exist to provide the playback application with the largest single buffer it will have to allocate. The layout of each frame is as follows:

 for each audio track
     four bytes        length of audio packet (bytes) plus four bytes. 
                       A value of zero indicates no audio is present for this track.
     four bytes        number of samples in packet
     variable length   Bink Audio packet
 variable length       Bink Video packet

Exe files

Bink data can be contained in exe files. To find where to start decoding search for one of 4 id's in the file:


Note that this is the BIK value in machine order (therefore it appears backwards for x86 binaries).

External Links