By Pritibhukhan Borah, Computer Science Engineer · Last updated: 2026-11-02
A container is not a codec
The codec (H.264, H.265, Motion-JPEG and so on) compresses the picture. The container (MP4, MOV, AVI) packs the compressed picture, the sound and an index into one file. Two files with the same extension can hold different codecs, which is why "it is an MP4" does not tell you whether a player or a repair tool can read it.
MP4
MP4 is built on the ISO base media file format. It stores data in nested boxes: a large mdat box with the frames and a moov box with the index and codec settings. It is the default for most Android phones, action cameras, drones and many dashcams, and plays almost everywhere.
MOV
MOV is Apple's QuickTime format, and MP4 was derived from it, so the structure is very similar. iPhones record .mov files, usually with H.264 or H.265 video. Professional codecs such as ProRes also live in MOV, but they are a different matter from the camera-style H.264 and H.265 files covered by a repair like MOV repair.
AVI
AVI dates from 1992 and is based on Microsoft's RIFF format. The video and audio are stored as small labelled chunks with an index called idx1 near the end. It appears in older digital cameras (often with Motion-JPEG video), camcorders, some dashcams and DVR recorders. It was not designed for modern features such as frame reordering or variable frame rate, so files from some devices rely on workarounds.
Side-by-side
| MP4 | MOV | AVI | |
|---|---|---|---|
| Origin | ISO standard | Apple QuickTime | Microsoft, 1992 |
| Index | moov box | moov atom | idx1 chunk |
| Index usually written | When recording stops | When recording stops | When recording stops |
| Typical sources | Android, action cameras, drones | iPhone, Mac apps | Older cameras, camcorders, DVRs |
| If the index is lost | Needs codec settings from a reference | Needs codec settings from a reference | Frames are self-describing, usually no reference |
Why this matters for repair
MP4 and MOV recordings keep their codec settings in the moov box. Lose it and the frames are still there, but a repair needs those settings from a healthy file made on the same device. AVI chunks carry a label for each frame, and the main header describes the streams, so an AVI can often be rebuilt on its own. That is why the tool asks for a reference video for MP4 and MOV but not for most AVI files.
MKV, WMV and MTS are other containers you may meet. This tool does not read them.
Related
Frequently asked questions
Is MOV the same as MP4?
They are close relatives with a very similar structure, but not identical. Many players treat them alike, yet some details differ, so do not assume a file will behave the same after renaming it.
Can I just rename a .mov file to .mp4?
Sometimes it plays, because the structure is similar. It does not repair anything, and a damaged file stays damaged after a rename.
Which format survives a crash best?
AVI is the easiest to rebuild because each chunk labels itself. MP4 and MOV hold their index in one place at the end, so losing it needs a healthy reference clip.