AVI (Audio Video Interleave) was Microsoft's answer to Apple's QuickTime in 1992, and for a decade it was the dominant video format on Windows PCs. If you have home movies recorded on a mini-DV camcorder, old CCTV footage, or videos from the early digital camera era, they're probably in AVI. The format served its purpose for decades, but in 2024 it's effectively obsolete — modern platforms have dropped AVI support entirely, and most new playback software handles it as an afterthought. Converting to MP4 brings those old recordings into a format the modern world understands.
Why AVI Files Are Problematic Today
AVI is genuinely painful to deal with today:
- iPhones and Android phones cannot natively play AVI in any built-in app
- YouTube, Instagram, TikTok, and most platforms reject AVI uploads
- AVI files often use old codecs — DivX, Xvid, MPEG-2 — that modern software doesn't support without installing codec packs
- AVI has no container-level support for modern streaming or seeking in large files
- AVI files are typically much larger than equivalent MP4 files with H.264 video
- Browsers cannot play AVI in an HTML5 video element
The Codec Problem
AVI is a container, not a codec. The actual video inside an AVI file could be encoded with any number of codecs — DivX 3.11, Xvid, MPEG-2, Indeo Video, Cinepak, or uncompressed video. This is part of why AVI is so difficult today: you might have the right software to open AVI, but not the right codec to decode the specific video stream inside. MP4 with H.264 standardises on a single, universally-supported codec, eliminating this problem entirely.
How to Convert AVI to MP4 Online
Convifi converts AVI to MP4 directly in your browser, so your old family videos stay on your device and aren't sent to any server.
- Visit convifi.com/convert/avi-to-mp4
- Select your AVI file by clicking or dragging it to the drop zone
- Choose "Fastest" preset if you just need a quick result; "Balanced" for better quality
- The conversion runs locally using FFmpeg compiled to WebAssembly
- Download the universally-compatible MP4
How Much Smaller Will the MP4 Be?
This depends heavily on the codec inside the AVI file. Old AVI files encoded with DivX or Xvid are already H.264-comparable in compression — converting to MP4 won't reduce size dramatically, just change the container. However, if the AVI uses an older, less efficient codec (like DivX 3, MPEG-1, or uncompressed video), re-encoding to H.264 MP4 can reduce file size by 40–70% at equivalent quality. Uncompressed AVI camcorder footage is an extreme example — a 10 GB raw video file can become a 1–2 GB H.264 MP4 with no perceptible quality loss for screen viewing.
Digitising Old Camcorder Tapes
Many people have old VHS or Hi8 tapes they've digitised to AVI using a USB capture card. These raw captures are typically uncompressed or lightly compressed and extremely large. Converting to MP4 is the right move — it makes the files manageable in size, compatible with every device and cloud service, and ready for sharing with family. For archival purposes, keep a copy of the original AVI if storage allows.
What About CCTV and Security Camera AVI Files?
CCTV DVR systems often save footage as AVI files using proprietary codecs like MPEG-4 ASP or older DivX variants. Converting these to MP4 makes them playable in VLC, shareable with police or insurance companies, and uploadable to cloud storage. If the CCTV codec isn't supported by standard WebAssembly FFmpeg builds, you may need to use a desktop FFmpeg installation instead.
AVI to MP4 on Mac
Macs haven't included DivX or Xvid codec support since macOS dropped 32-bit apps in Catalina. QuickTime on modern Macs often can't even open AVI files. The browser-based converter sidesteps this entirely — it uses its own bundled FFmpeg with all necessary codecs included. Alternatively, VLC on Mac can play most AVI files and can convert via Media > Convert.
Long-Term Archival: MP4 vs AVI
For preserving old home videos, MP4 is the better long-term archive format. It's the ISO standard (ISO/IEC 14496-14), supported by every major platform, cloud service, and NAS system. It will be readable in 20 years. AVI is a format from 1992 that's already losing support — don't bet your family memories on it.