Canon EOS Rebel T6i EF-S 18-55mm IS STM Lens Kit Instruction Manual - Page 254

General Movie Shooting Cautions Recording and Image Quality  If you use a card with a slow writing speed, a five-level indicator may appear on the right of the screen during movie shooting. It indicates how much data has not yet been written to the card (remaining capacity of the internal buffer memory). The slower the card, the faster the indicator will climb upward. If the indicator becomes full, movie shooting will stop automatically. Indicator If the card has a fast writing speed, the indicator will either not appear or the level (if displayed) will hardly go upward. First, shoot a few test movies to see if the card can write fast enough. Still Photo Shooting During Movie Shooting  Regarding the image quality of still photos, see "Image Quality" on page 218. Playback and TV Connection  If you connect the camera to a TV set (p.298-301) and shoot a movie, the TV set will not output any sound during the shooting. However, the sound will be properly recorded. Restrictions on MP4-format Movies Note that generally the following restrictions apply to MP4-format movies.  Sound will not be recorded on approx. the last two frames.  When you play back movies on Windows, images and sound may become slightly out of synchronization. 254