Why PC-Formatted Memory Cards Can Fail During Recording

Experienced cinematographers often know that using a memory card formatted on a computer via a USB card reader can lead to issues such as:

• Recording stopping unexpectedly during shooting

• The contents of the memory card not appearing after filming

For this reason, it is widely recommended to always format memory cards inside the camera before use.

There are many possible causes of recording interruption or data corruption (see our previous blog post, “Long-Duration Recording Errors”), but the two major format-related causes are:

1. Improper initialization of the file system area

2. Incorrect partition configuration

In this chapter, we will focus on problems that occur when the file system is not properly initialized.

What You Need to Know First:

Basic Behavior of NAND Flash

To understand why these issues occur, it helps to briefly understand how NAND Flash — the storage medium inside memory cards — operates.

While specifications vary by manufacturer, a typical modern 64GB SD card may roughly look like this:

NAND Flash has several important characteristics:

•   Data can be written at the page level

•   Erasing can only be done at the block level

•   Already-written data cannot be overwritten directly

Because of these limitations, modern SD cards use Dynamic Mapping inside the Flash Translation Layer (FTL):

• Instead of overwriting existing data

• New data is written to a different free location

• Only the address mapping is updated

After many updates, data becomes scattered across different blocks — a condition often called fragmentation. The controller later reorganizes data using background Garbage Collection (GC).

However, if power loss or an error occurs during this process, files may become corrupted.

Understanding the File System Structure

Next, let’s briefly look at how the file system works.

A 64GB SD card formatted with exFAT is typically divided into:

•   About 32MB (≈0.05%) → File system area (stores file location information)

•   About 99.95% → Data area (actual video recordings)

During recording, two completely different types of data are written:

1.    Actual video data

2.    File system data that manages file location and structure

These two types behave very differently:

Data Write Characteristics During Recording

Video data is written only once, but the file system table is updated continuously throughout recording. As a result, after filming, the file system area is often heavily fragmented.

Why Does Formatting on a Computer Cause Problems?

Here is the key question:

Why can formatting on a computer lead to instability?

When observing the formatting process with a USB analyzer, we can see that a computer does not fully reinitialize the file system area. Instead, it overwrites only small portions of it in a scattered manner.

For example:

• The total file system area is about 32MB

• But only about 500KB of data is actually updated during a typical PC format

This means the file system area is not fully reset — it is partially overwritten on top of existing data, leaving the internal state more complex.

In this condition:

•   Internal management overhead increases

•   Garbage Collection becomes more likely

•   Sudden latency spikes may interrupt recording

In severe cases, the file system itself can become corrupted, making the card unreadable.

How OFFLOADER Batch Formatting Is Different

OFFLOADER’s batch card format feature is designed with NAND Flash behavior in mind.

It:

•   Properly reinitializes the file system area

•   Reduces internal management overhead

• Helps maintain stable write performance during recording

  
  

This provides a level of formatting stability comparable to in-camera formatting.

Difference from Camera “Full Initialization”

Some high-end cameras offer a deep initialization feature that wipes not only the file system area but also the data area.

In such cases:

•   Data recovery may become impossible.

OFFLOADER formatting works differently:

•   The data area remains untouched

•   Only the file system area is reinitialized

This approach improves stability while still preserving the possibility of data recovery when needed.

Next Section

In the next chapter, we will look at another common cause of errors: problems caused by incorrect partition settings on memory cards.

#MemoryCardFormat #PCFormat #CameraReady #RecordingStability #FileSystem #NANDFlash #OFFLOADER16X #ClouZen