Dash Cam Loop Recording Explained: Segments, Locks and SD Cards

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Loop recording is the trick that lets a dash cam record for years on a microSD card that holds a few hours. When the card fills up, the camera quietly deletes the oldest unlocked clip and keeps going, like a goldfish that forgets the first lap of the bowl. Every camera covered below does it. What differs is how long each clip is, what happens to the clips you lock, and how often the maker wants you to wipe the card.

Most shoppers meet loop recording as a checkbox on a spec sheet and only learn the details after something goes wrong: a clip that is not there, a card that reports errors, a loop that seems to have lost the plot. The mechanism is simple. The trouble hides in segment length, locked files and the card itself.

One note on sourcing, said once and plainly. This guide is built from manufacturer manuals, product pages and support articles for the VIOFO A229 Pro, Vantrue N5, Nextbase iQ and Nextbase 622GW, plus the spec sheets for the hardwire kits and microSD cards that go with them. It is not based on our own use of these cameras, so anything described as behavior is what the maker documents, and anything described as an owner experience is labeled that way.

Loop Recording at a Glance

Two of those cells carry footnotes. Vantrue's own shop text still says 512GB max, while its manual says 1TB. And Nextbase's 622GW paperwork contradicts itself on 256GB cards. Both are unpacked below.

How Dash Cam Loop Recording Works

A dash cam does not write one endless file. It chops the drive into segments and saves them in sequence. Per VIOFO's A229 Pro manual, when the card runs short of space the camera overwrites the oldest files one by one. Nextbase describes the same idea as continuous recording that carries on even when the card reaches full capacity. In storage terms it is a first-in, first-out queue.

The exception is anything locked. When the G-sensor feels a collision, or you press the protect button, the current clip is set aside where the loop will not touch it. Each brand keeps these files in its own place:

• VIOFO A229 Pro: locked files go to a folder called RO inside DCIM\Movie and are not overwritten by loop recording.
• Vantrue N5: an Event folder holds clips triggered by the G-sensor or locked by hand, while a Normal folder holds loop, parking, time-lapse and privacy footage.
• Nextbase 622GW: the manual states that protected files will not be deleted.

That separation is the whole point of the feature, since it keeps accident footage safe. It is also the root of the most common headache, which comes up in a moment.

The 4GB file limit

Most dash cams format cards as FAT32, which caps a single file at 4GB. Per Vantrue, any video longer than roughly half an hour tends to blow past that cap, which is why no camera on this list hands you an hour-long loop file. VIOFO's manual tells you to format to exFAT or FAT32, so check what your camera does when it formats the card itself.

Loop Segment Length: What You Can Change

Segment length is the first loop setting most cameras let you touch. Here is what the manuals say:

• VIOFO A229 Pro: 1, 2, 3, 5 or 10 minutes.
• Vantrue N5: 1, 3 or 5 minutes, or off, with 1 minute as the default (manual V5.3).
• Nextbase 622GW: 1, 2 or 3 minutes, with 1 minute as the default.
• Nextbase iQ: 30-second segments. Nextbase documents no setting to change that.

The iQ deserves a second look. Per Nextbase's support article, each 30-second segment produces a high-resolution and a low-resolution file for every active camera. With front, cabin and rear cameras all running, that is up to six files every 30 seconds. Expect to browse by event in the app, not by file.

Which length should you pick? No maker publishes a universal answer, so this is editorial opinion: longer segments mean fewer files to scroll through, shorter ones mean smaller files that are easier to copy. The default is a sensible place to start.

One gotcha on the Vantrue N5: its privacy mode keeps only the latest three recording files, each new loop file overwriting the oldest. If a camera seems to remember almost nothing, check that setting.

Gaps Between Clips: Why Loop Recording Is Not Frame-Perfect

Spec sheets love the word continuous. The manuals for VIOFO and Vantrue do not say whether one file ends exactly where the next begins, or whether a sliver of road falls between them. Nextbase, for its part, lists gaps between recordings among the symptoms of a card that has not been formatted, which treats them as a fault rather than a design feature. Owners on forums report gaps at clip boundaries on some cameras, though no figure from those reports is solid enough to repeat here.

The practical takeaway is to treat the loop as a very good net with a few holes, not as a frame-perfect archive. If something important happens, the layers around it matter:

• a G-sensor tuned to lock the right clips without locking every pothole
• a camera with buffered recording when parked, so the seconds before an event are kept
• cloud upload, where the camera offers it. The Nextbase iQ, for instance, sends events to Nextbase Cloud with a Protect or Protect Plus subscription

After an incident, look at both the locked files and the normal loop clips around the same time. It costs nothing, and the second folder sometimes holds the bit the first one missed.

Locked Files, Full Cards and the Format Question

Here is the headache promised earlier. Locked clips live outside the loop, so a G-sensor that is too jumpy will slowly stuff the card with videos of speed bumps and slammed doors. Nextbase says a build-up of protected files stored on the card shortens recording time. No manufacturer text we found says the loop stops dead, but a card full of protected clips has less room to loop in, and that is reason enough to keep the sensitivity sensible.

VIOFO's manual recommends setting the G-sensor to Low. The options are Off, Low, Middle and High. Use the manual lock button for the moments that count.

Then there is formatting, where the brands disagree politely:

Nextbase lists what an unformatted card can lead to on the iQ: SD card errors, recording failure, a frozen device, gaps between recordings, and corrupted or unplayable files. Before you format, copy off anything you want to keep. Formatting is the digital equivalent of emptying the glovebox onto the driveway, so make sure nothing you need is in there.

Loop Recording on Four Popular Dash Cams

VIOFO A229 Pro

The A229 Pro comes as a 1CH (front), 2CH (front and rear) and 3CH (front, rear and cabin). On the front, VIOFO lists a Sony STARVIS 2 IMX678 sensor at 4K 30 fps with a 140 degree field of view and HDR. The 3CH page lists a Sony STARVIS 2 IMX675 rear camera at 2K and a 1080p interior camera. All of that is manufacturer data. The A229 Pro is still on sale, but VIOFO now has a newer A329 and A329S line as well, so it is no longer the top of the range.

• Loop segments: 1, 2, 3, 5 or 10 minutes.
• Card: the manual says the card must be high endurance, up to 512GB.
• Parking: Auto Event Detection is buffered, saving 15 seconds before and 30 seconds after the detected event, per VIOFO. The manual says parking mode works only with the engine off and a USB Type-C hardwire kit supplying continuous power, and recommends the VIOFO HK4.
• Heat: the manual advises time-lapse parking in hot summers and turning the camera off if the cabin passes 60 C.

The Amazon listing linked below is specifically the A229 Pro 3CH, so check the channel count before ordering another version.

Check the VIOFO A229 Pro 3CH on Amazon

For more on the brand, see our VIOFO dash cam guide.

Vantrue N5

Vantrue sells the N5 under the product title Nexus 5. It is a four-channel camera: a front camera at 1944P (2592x1944), plus front-cabin, rear-cabin and rear cameras at 1080P. The front sensor is a Sony STARVIS 2 IMX675, and the camera uses a supercapacitor and a Novatek chipset, per Vantrue.

• Loop segments: 1, 3 or 5 minutes, or off. Default is 1 minute.
• Card: the manual gives a range of 32GB to 1TB, U3 and Class 10. Vantrue's shop description and the Amazon title still say 512GB max, so if you plan to buy a very large card, read the manual for your firmware first.
• Parking: Vantrue says the camera saves 10 seconds before and 30 seconds after an event, and that it must be hardwired to use parking mode. Hardwire kits are sold separately.

A newer sibling, the Nexus 5S (N5S), appeared on Vantrue's site in July 2025 with a 1440P rear camera and an optional LTE module. Availability signals for the N5 itself are mixed, so confirm that it is actually in stock before you commit.

Check the Vantrue N5 on Amazon

More on the brand is in our Vantrue dash cam guide.

Nextbase iQ

The iQ is a connected 4G dash cam sold with a 1K (1080p), 2K (1440p) or 4K (2160p) front camera, plus a cabin camera and an optional 2K rear window camera. Nextbase's page does not name the sensors, so any sensor model you see quoted elsewhere is unconfirmed here.

• Loop segments: 30 seconds, as described above.
• Card: a 64GB U3 card ships in the box per Nextbase's page. Nextbase sells a 256GB U3 industrial-grade card that it lists as compatible with the iQ.
• Power: the box includes an OBD power cable and a hardwire cable with fuse taps. Nextbase's page says the camera plugs into the OBD port, or you can hardwire it to a live fuse for the smart features.
• Parking and cloud: Smart Sense Parking combines radar with the G-sensor, and it, along with Witness Mode, needs a Protect or Protect Plus subscription. The Solo tier is free.

The Amazon listing linked below is the iQ 4K in a bundle with a 64GB card. It does not cover the 1K or 2K versions.

Check the Nextbase iQ 4K on Amazon

If always-connected cameras interest you, our LTE dash cam explainer covers the trade-offs.

Nextbase 622GW

The NBDVR622GW is a 4K touchscreen model from the Series 2 era, with a manual dated 2020. Nextbase's own page currently shows it as out of stock in places, so treat it as a legacy camera that may be hard to find new. If you already own one, here is how its loop behaves.

• Loop segments: 1, 2 or 3 minutes, default 1 minute. The oldest file is deleted when the card is full, and protected files are not deleted.
• Format: the manual recommends formatting every 2 to 3 weeks.
• Card: a U3 card is required, and the manual's spec table lists 8GB to 128GB. A different message in the same manual mentions 256GB as the maximum, and Nextbase's 256GB card page lists the 622GW as compatible. With the paperwork pulling both ways, check Nextbase's current compatibility list before buying a card above 128GB.
• Parking: Intelligent Parking Mode wakes the camera when the car moves and records a 45-second protected video, then returns to standby after 5 minutes without movement. The protect button saves 15 seconds before and 30 seconds after the press. The manual describes no buffered parking.

Nextbase also says a dash cam needs a continuous write speed of at least 48MB/s and that standard cards fall short of that. That is Nextbase's position, and it is why the company steers owners toward its own industrial-grade cards.

Check the Nextbase 622GW on Amazon

Our Nextbase 622GW page goes deeper on this model.

Parking Mode and the Hardwire Requirement

Loop recording while you drive works from any power source. Parking recording does not. A cigarette-lighter adapter shuts off with the ignition, and a camera with no power records nothing, however clever its buffer. For buffered parking you need constant power from a hardwire kit or a battery pack. Our parking mode guide covers the modes in depth.

Two kits fit the cameras above.

VIOFO HK4. This is a USB Type-C kit with ACC detection that switches the camera between driving and parking mode. VIOFO lists four voltage cut-off options and support for 12 to 24V vehicles, and the Amazon listing gives the cable length as 13.1 ft (4 m). It lists the A229 Pro among its compatible cameras. The ASIN linked below is the version without fuse taps, so you will need to buy a fuse-tap set separately or pick a variant that includes one. The exact cut-off voltages circulate online, but we could not confirm them on VIOFO's own pages, so check the numbers in your kit's documentation. The A329S line uses a newer kit called the HK6.

Check the VIOFO HK4 hardwire cable on Amazon

Vantrue Universal 11.5ft ACC Hardwire Kit. Vantrue lists this USB-C kit as fitting the N5 and N5S among many others. Its specs are 12 to 24V input, 5V and 2A output, and an 11.5 ft cable, with low-voltage protection at 11.6V for a 12V vehicle. Vantrue's own sources disagree on the 24V cut-off figure, so we are leaving it out. Vantrue also sells a 5-Level Adjustable kit and a Voltage Display kit, but the compatibility list we found for the 5-level kit did not name the N5, so confirm before ordering.

Check the Vantrue Universal 11.5ft ACC Hardwire Kit on Amazon

Whichever kit you pick, the wiring logic is the same. VIOFO's listing for the HK4 says the red battery cable goes to constant power and the yellow ACC cable goes to an ignition-switched circuit. Swap them and the camera cannot tell when you have parked. A higher cut-off voltage protects the car battery at the cost of shorter parking recording. Our guide to a dash cam draining your car battery explains the trade, and our installation guide walks through the wiring. For more kit options, see the hardwire kit roundup.

SD Cards: The Part That Quietly Breaks Everything

A loop writes to the same card over and over, in a hot windshield, for years. An ordinary camera-phone card was not built for that job. The camera makers agree on the broad point, even if they disagree on the details:

• VIOFO: the manual says the card must be high endurance, and VIOFO sells its own industrial-grade microSD.
• Vantrue: only Vantrue, Samsung Endurance and SanDisk High or MAX Endurance cards are recommended. Samsung EVO Plus and PRO Plus are explicitly not recommended.
• Nextbase: recommends its own industrial-grade U3 cards only.

Here are three endurance cards in the 256GB size, with figures taken from the manufacturers' own pages and datasheets:

A word on the SanDisk High Endurance row, because it trips people up. The Amazon listing title says up to 40,000 hours, but SanDisk's datasheet gives 20,000 hours for the 256GB size. The 40,000-hour figure belongs to the 512GB card. When a listing and a datasheet disagree, go with the datasheet.

On the class labels: U3 and V30 are SD Association speed classes, and SanDisk describes V30 as a sustained video capture rate of 30MB/s. That is the baseline for cards in a 4K camera.

All of these are manufacturer claims about hours and speeds, and none of them is a promise about how a card will behave in your particular windshield. For the wider picture, see our guide to high-endurance microSD cards.

Check the Samsung PRO Endurance 256GB on Amazon

Check the SanDisk High Endurance 256GB on Amazon

Check the SanDisk MAX Endurance 256GB on Amazon

A Sensible Loop Setup

None of this is a manufacturer mandate, so read it as a starting point built from the documentation above:

• Segment length: begin at the default and change it only if scrolling or copying files annoys you.
• G-sensor: Low during normal driving, per VIOFO's advice, with the manual lock button for real events.
• Formatting: follow your brand's range from the table above, and use the format reminder if your camera has one.
• Card: a high-endurance U3/V30 card from the capacity range your camera supports.
• Parking: buffered modes only when the camera is hardwired, and time-lapse or low-bitrate modes for long stays, especially in a hot car.
• Backup: if your camera can upload events to the cloud, switch it on. A copy that lives off the card cannot be overwritten by it.

Frequently Asked Questions

Where to Go Next

If loop behavior is part of how you choose, pick a model that lets you set segment length and offers buffered parking for control, and one with cloud upload for a copy that lives off the card. Our best dash cams with parking mode and cloud-connected dash cam guide pick up from here.