Motion JPEG

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  • FourCCs: ACDV, AVDJ, AVI1, AVI2, AVID, AVRn, CJPG, dmb1, IJLV, IJPG, jpeg, MJPG, mjpa, mjpb, MTSJ, MVJP, QIVG, SLMJ, ZJPG (these are known FourCCs; there are probably many others)
  • Company: Independent JPEG Group, Pegasus Imaging, many others

Motion JPEG (a.k.a. MJPEG) is a sub-category of motion video codecs where successive frames are encoded using the standard JPEG algorithm. No interframe compression is performed and the resulting encoded data generally does not achieve the same level of compression as a codec using interframe techniques. However, decompression is usually faster and any frame can be referenced independently since there are no dependencies on other frames. Plus, there are fewer legal caveats when using the open JPEG standard.

Note that 'MJPEG' does not describe a single format. Many entities have created formats that can be described as MJPEG, though they have subtle differences from each other.

  • MJPEG can be identified with a lot of different FourCCs in AVI files (each likely corresponds to a different VfW codec binary.
  • QuickTime files can store 2 variations of MJPEG: types A and B, denoted with the FourCCs 'mjpa' and 'mjpb' respectively.
  • Nintendo GameCube games often use a format called THP which stores video as JPEG frames but without escape codes.
  • SMJPEG files used in certain games contain sequences of plain JPEG files.