AVI files can contain both audio and video data, widely accepted but with larger file sizes.
Common Uses
Windows video playback
Legacy video storage
Video editing interoperability
AVI Transformation FAQ
What is an AVI file?
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AVI (Audio Video Interleave) refers to a multimedia container format introduced by Microsoft.
Why does AVI behave so differently from modern video files?
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Because it predates them by a decade. AVI is a RIFF chunk file: a flat sequence of interleaved audio and video chunks with an index bolted on the end. There is no concept of a variable frame rate, no place to put a subtitle stream, and the index is why a truncated file often will not seek at all. Everything awkward about the format traces back to that layout. AVI is Microsoft’s Audio Video Interleave, introduced in 1992 on top of the RIFF chunk format — one of the oldest containers still in circulation. AVI has no native support for modern codecs, variable frame rate, soft subtitles or files over 4 GB without hacks, and its per-chunk overhead bloats the file.
Why do camcorders and capture cards still produce AVI?
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Because the format is simple enough to write in real time on modest hardware, and because a generation of capture equipment was designed around it and never updated. The device is not making a quality judgement, it is writing what its firmware knows. That is also why these files are large for what they contain and why converting them is usually the first thing anyone does.
Why will my browser not play an AVI file?
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Browsers ship decoders for a deliberately short list of formats, and AVI is not on it — the licensing, the codec variety it permits, or simply its age keeps it out. The file is not broken and a desktop player will open it, but nothing you do to the page will make a browser render it. Converting to a web-native container is the only reliable route to inline playback.
Why does my AVI footage show comb lines on anything that moves?
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Because it is interlaced. Content in this format very often comes from the broadcast and DVD era, where each frame is stored as two half-height fields captured a fiftieth of a second apart. A progressive screen displays both at once, so movement between the two exposures appears as horizontal combing. Deinterlacing on conversion weaves the fields into whole frames and the artefact disappears for good.
Why are my AVI recordings split into numbered parts?
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A format-level ceiling, not a fault in the recorder. AVI has a practical single-file limit that long or high-bitrate material runs straight into, so capture software splits the recording rather than producing a file it cannot index. Converting to a container with no such limit lets the pieces be rejoined into one continuous video, which is usually the real reason people convert this format at all.
Why does AVI playback stutter or run hot on older machines?
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Because it is being decoded in software. Hardware video decoders only cover a fixed list of formats, and AVI is outside it on most devices, so every frame is reconstructed by the CPU instead. On a current desktop that is merely wasteful; on a phone, an older laptop or a smart TV it shows up as dropped frames, fan noise and battery drain. Converting to a hardware-supported format removes the problem entirely. AVI files predate modern codecs: expect MPEG-4 Part 2 (DivX/Xvid), Motion JPEG or raw uncompressed frames rather than H.264.
Should I still be saving new files as AVI?
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Only if something downstream demands it. The format still opens, and there is no urgency about converting an archive that is not causing trouble, but it is no longer where the tooling or the efficiency is going. For anything new, a current format costs nothing extra and avoids the next round of this question a few years from now.
Where do subtitles go for an AVI file?
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Beside it, or into the picture. AVI has no subtitle stream of its own, so the two options are a sidecar .srt file the player loads alongside the video, or burning the text into the frames during a re-encode. The sidecar keeps the subtitles editable and switchable but travels as a second file that is easy to lose; burning in survives any transfer but cannot be turned off afterwards.
Does it matter that AVI is over thirty years old?
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Age itself is not the problem — several formats from that era are still perfectly good, precisely because everything has had decades to implement them. What matters is what the era assumed: small files, modest processors, no network, and features nobody needed yet. Where those assumptions still fit, the format is fine. Where they do not, that is the reason to convert.
Can one AVI file hold several audio tracks?
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Yes — an original-language mix, a dub and a commentary can all sit in the same file with the player switching between them. Two cautions: many phone and television players expose only the first track however many are present, and a conversion into a format without real multi-track support keeps one track and drops the rest. Pick the track you want before converting, rather than discovering afterwards which one survived. AVI is trivially simple, which is exactly why ancient camcorders, capture cards, DVD ripping tools and Windows-era software all still emit it.
Why does AVI only really work properly on Windows?
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Because the container is the easy half. AVI was specified around Microsoft's own codecs, and almost nothing outside Windows ships a decoder for those — so the file opens, reports its duration, and then produces no picture or no sound at all. Installing a codec pack is the old answer and a fragile one; converting the payload into something every platform already decodes is the durable one.
