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Fraps splits recordings at 4 GB: why, and how to join the files

Fraps splits recordings at 4 GB when the drive uses FAT32, which cannot hold a bigger file, when you run a version older than 3.5.0, or when the "split at 4 gigabytes" option is on. Fraps 3.5.0 and later write one large file on NTFS and exFAT drives. Split files can be joined back together without re-encoding.

Why the 4 GB limit exists

FAT32's largest possible file is 4 GiB; NTFS and exFAT allow files far larger. Until version 3.5.0 (April 2012), Fraps split every recording at 4 GB to stay inside the limits of the original AVI format. Version 3.5.0 added "hybrid OpenDML/AVI" files over 4 GB on NTFS drives, and 3.5.1 extended that to exFAT.

Beepa kept an option to split at 4 GB "for legacy AVI 1.0 support". Wikipedia adds that splitting also limits the damage if the game crashes, since only the last part is lost.

Recording one file

  1. Install Fraps 3.5.99 from fraps.com.
  2. Record to a drive formatted as NTFS or exFAT. In File Explorer, right-click the drive, choose Properties and read "File system".
  3. Turn off the option to split movies at 4 gigabytes in the Movies tab.

Joining split files with ffmpeg

Splitting at 4 GB and joiningTop row: four files, three of 4 GB and one of 1.3 GB, written one after another. Bottom row: the same footage as one 13.3 GB file after joining.What the recorder writes4 GB4 GB4 GB1.3 GB After joining with a stream copyone file, 13.3 GB, no re-encode
The split files follow on from each other frame for frame, so a stream copy puts them back together without changing a pixel.

ffmpeg's concat demuxer reads a list of files and plays them one after another, and with -c copy it copies the video and sound without re-encoding. Create a text file named list.txt:

file 'game 2026-11-07 20-15-02-11.avi'
file 'game 2026-11-07 20-15-02-11 (2).avi'
file 'game 2026-11-07 20-15-02-11 (3).avi'

Then run:

ffmpeg -f concat -safe 0 -i list.txt -c copy joined.avi

The files must have the same streams, meaning the same codecs and settings, which split parts of one recording always do. -safe 0 lets the list use names with spaces and full paths. Names with quotes in them need escaping.

Joining in VirtualDub

VirtualDub can open the first part and add the rest with File, Append AVI Segment, as long as the parts share one format. Save with Video, Direct Stream Copy to keep the original quality. See the VirtualDub guide.

Sources

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