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2. SD cards: choosing and preparing

The SD card is the device's offline storage, so choosing the right card matters. Counterfeit or capacity-faked cards make the device fail to recognize the card or refuse to record after it is inserted. Always buy genuine cards.

Requirements​

  • Format: FAT32. Format on a computer, or with the app's Format SD card button. The app preserves the card's recognized filesystem; blank or unrecognized cards are formatted as FAT32.
  • Capacity: 128 GB or less recommended.

Choosing a card​

  • ✅ Known to work: genuine cards from mainstream brands such as Movespeed A1 V30, Biwin, SanDisk.
  • ❌ Beware of fakes: counterfeit and capacity-faked cards are common on marketplaces such as Taobao. Buy from reputable channels (for example JD self-operated) to avoid a card that won't record or that corrupts recordings.

One SD card ships with the device. We recommend the Movespeed A1 V30 128 GB.

Verify real capacity​

Run a new card through H2testw (a graphical tool for Windows) on a computer before using it, to confirm it really has its advertised capacity. On macOS or Linux, F3 does the same job. This avoids corrupted recordings from a capacity-faked card.

Insert or remove the card only while the device is unpowered.

Under the hood​

Speed class​

Use a card rated at least A1 and V30. These classes sustain the write rate of two 1080p H.265 streams; higher classes (A2, V60, V90) are fine. A slower card may mount but fail to record. The shipped card meets this, so matching it (A1 / V30, 128 GB, reputable brand) is the safe way to buy spares. A genuine V30 card sustains 30 MB/s, which clears every bitrate preset with room to spare; what bites in practice is a counterfeit or worn-out card that never delivers its rating, and a higher bitrate is what exposes it.

exFAT and ext4​

FAT32 is what the shipped card uses and what the manual recommends. exFAT and ext4 also work: the device identifies the filesystem by trying to mount it, so there is nothing to configure. A card it cannot mount is left alone rather than reformatted; the device reports no card inserted, and your data is never silently wiped.

ext4 is the most robust choice for Linux hosts, because it is journaled: the filesystem stays consistent if the device loses power mid-write, and a host browsing the card over USB while the device opens a new session directory cannot read inconsistent directory entries.

Modern Linux formats an ext4 card the device cannot read

The device firmware runs Linux kernel 5.10. Current distributions (Debian 12+, Ubuntu 23.04+) ship e2fsprogs 1.47 or newer, whose mkfs.ext4 enables the orphan_file feature by default, which needs kernel 5.15. A card formatted with a plain mkfs.ext4 on such a host will not mount; the device behaves as if no card were inserted. Format ext4 cards with the incompatible features disabled:

mkfs.ext4 -F -O ^orphan_file,^metadata_csum_seed /dev/sdX1

If a card formatted this way still isn't recognized, reformat it as FAT32 or exFAT instead.

Formatting from the app​

Device info → Format SD card in the Visio Companion app erases and formats the card in place. The app preserves a recognized filesystem and uses FAT32 for blank or unrecognized cards. Since firmware 1.1.0 this also initializes a brand-new, unpartitioned card, so no computer is needed. See Firmware release notes.