Canon EOS 7D Mark II Basic Instruction Manual page 147

3 Setting the Movie Recording Size
Compression Method
W ALL-I (For editing/I-only)
Compresses one frame at a time for recording. Although the file size
is larger than with IPB (Standard) and IPB (Light), the movie is more
suited for editing.
X IPB (Standard)
Compresses multiple frames at a time efficiently for recording. Since
the file size is smaller than with ALL-I (For editing), you can shoot
longer (with the same card).
IPB (Light)
Selectable when the movie recording format is set to [MP4]. The
movie is recorded at bit rate lower than with IPB (Standard) resulting
in a smaller file size and compatibility with a larger range of playback
systems. Of the three methods available, this method allows the
longest total possible movie shooting time on a card of a given
capacity.
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