How to choose the right reference file for video repair

By the FixMP4 engineering team · October 2, 2026 · 6 min read

When a video loses its index, it also loses its codec settings. That is why FixMP4, like every serious video repair method, asks for a reference file: a healthy video recorded by the same device with the same settings. Choosing the right one is the single biggest factor in a successful repair. This guide explains what "the same settings" means and how to get a good reference for common devices.

What the reference file is used for

From the reference, FixMP4 copies:

• the codec configuration: for H.264 the SPS/PPS parameter sets, for HEVC the VPS/SPS/PPS, for AAC audio the AudioSpecificConfig (sample rate, channels, profile);
• the timescale and frame duration, for example 1/30 or 1/29.97 of a second;
• the track layout: which tracks exist and in what order;
• the display settings such as rotation.

The frames themselves always come from your broken file; nothing from the reference ends up in your repaired video except these settings.

The golden rule: same device, same settings

A reference works when its codec configuration matches the broken file exactly. In practice that means:

• same device (the same phone or camera model, ideally the very same unit),
• same resolution (1080p vs 4K),
• same frame rate (24, 25, 30, 50, 60 fps...),
• same codec (H.264 vs HEVC),
• same audio setting (stereo vs mono, sample rate),
• same special modes (HDR, log profiles, stabilisation modes that change resolution).

The content does not matter at all. Five seconds of your floor is a perfect reference.

Where to find a reference

The easiest reference is a video recorded on the same day, just before or after the broken one. Look in the same folder on the memory card or in your phone's gallery. If you cannot find one, record a new clip with the same settings.

Device-specific tips

iPhone

• Check Settings > Camera > Formats: "High Efficiency" records HEVC, "Most Compatible" records H.264.
• Check Settings > Camera > Record Video for resolution and frame rate, and whether HDR Video is on.
• Cinematic mode, Slo-mo and Action mode use different settings from normal video; record the reference in the same mode.
• ProRes recordings are not supported yet.

Android phones

Settings vary by manufacturer. Use the camera app's video settings to match resolution, frame rate and "HEVC / high efficiency" options. Avoid using a video edited or exported by another app as a reference: re-exported files have different settings.

GoPro

Match the resolution, frame rate, lens (Wide, Linear, SuperView) and the HEVC/H.264 option. GoPro chapters (files split around 4 GB) of the same recording make excellent references, because they were recorded seconds apart with identical settings.

DJI drones and Osmo cameras

For a drone, the colour profile matters as much as resolution: a D-Log reference will not decode a Normal-profile clip well. A clip saved earlier in the same flight is the safest choice.

OBS and screen recorders

The reference must use the same encoder (x264, NVENC, Apple VT, QuickSync), the same resolution, frame rate and audio settings. Record a few seconds with the same OBS profile. Note that hardware and software encoders with the same nominal settings produce different parameter sets.

Audio-only recordings

For audio files such as iPhone Voice Memos, a reference is often unnecessary, because the AAC configuration is simple and can be detected. FixMP4 assumes 48 kHz (the iPhone default) when no reference is given. If the preview sounds too fast or too slow, add any healthy recording from the same app on the same device.

How to tell that the reference is wrong

The free preview makes this easy:

• "No frames matching the reference were found": the codec or settings differ. Try another reference.
• The picture is garbled, green or grey: the resolution or parameter sets differ.
• Audio is too fast, too slow or high-pitched: the audio sample rate differs.
• Video plays but is rotated: the reference was recorded in another orientation.

Because the preview is free, you can try several references until one works and only then export.

Summary

• The reference donates settings, never content.
• Same device, same resolution, same frame rate, same codec, same mode.
• Files from the same session are the best references.
• Audio-only files rarely need one.

Ready? Open the repair tool or read about repairing MOV files.

• reference file
• repair