SD Card SPEC Minimum Sequentail Write Speed Read Speed Speed Class Application Speed Class UHS Speed Class Video Speed Class(New) Capacity SDHC (2GB~32GB) SDXC (32GB~2TB) SDXC (32GB~2TB) 90 MB/sec V90 8K video files at 60/120 fps (UHS bus) 60 MB/sec V60 30 ~ 45 MB/sec up to 90 MB/sec U3 V30 1080p and 4K video files at 60/120 fps (UHS bus) 10 ~ 14 MB/sec 17 ~ 20 MB/sec C10 U1 V10 Full HD (1080p) video recording and consecutive recording of HD stills ( High Speed bus, Class C10), real-time broadcasts and large HD video files (UHS bus, Classes U1 and V10) 6 MB/sec up to 16 MB/sec C6 V6 High-definition video(HD) recording including Full HD (from 720p to 1080p/1080i) 4~5 MB/sec 10 ~ 13 MB/sec C4 2 MB/sec C2 SD video recording
Please identify that the video recording time is set to limit, instead of fixed time. If card format is FAT32, the recording would be stopped as 4GB of recording is reached because a single file cannot exceed 4GB. This problem may be solved as long as card format is changed to NTFS or exFAT if the two formats are supported by the machine.