The Canon EOS-1D X has a maximum video recording time of 30 minutes for all formats. That limit is dependent upon multiple factors like camera settings, media storage size, camera power, and internal camera temperature. See details and notes below for more information.
Maximum continuous video recording times for the Canon EOS-1D X
All Formats & Frame Rates
If the recording time reaches 29 minutes, 59 seconds, recording will stop automatically.
Even if you record a movie exceeding 4GB, you can keep recording without interruption.
Using CF cards up to 128GB: The card will be formatted in FAT32. If the file size exceeds 4GB, recording will continue and a new file will be created automatically.
Using CF cards exceeding 128GB: The card will be formatted in exFAT. Even if the file size exceeds 4GB during recording, the movie will be saved as a single file.
An increase of the camera’s internal temperature may cause recording to stop before the maximum recording time is reached.