Why Won't My AVI File Play? How to Convert AVI to MP4 That Plays Anywhere

What is inside an AVI

AVI is a container: a box that holds a video stream and a sound stream, plus a note of which codec — which method of compression — each one uses. The box is the same in every AVI file. What differs is what was put in it, and that depends on what made the file.

That is why one AVI plays and another does not on the same machine: the extension says nothing about the codec. The player you used for years had the codec installed — often from a "codec pack" — and the new device does not.

Why it will not play

In a browser. Browsers do not open AVI at all. We loaded four AVIs — Microsoft MPEG-4 v2, Xvid, Motion JPEG and H.264 — into a video element in Chrome, and all four were refused at the first step, before any frame was decoded: Chrome would not unpack the AVI wrapper, even around H.264, a codec it plays every day inside MP4. Asked directly whether it can play AVI, Chrome answers with an empty string, which means no. So a browser-based player, a web page or a cloud drive's preview will not show the video either.

On phones and TVs. These play video with dedicated decoding hardware, built for the codecs in use today: H.264, HEVC and their successors. DivX, Xvid, Microsoft MPEG-4 and Motion JPEG were common before that hardware existed, and support for them is left to software — which iPhones, iPads and Apple's own players do not include for AVI, and which many TVs and phones include only partly.

On a computer. A desktop player with its own codecs, such as VLC, plays nearly every AVI. If you only need to watch the file on that computer, installing one is enough. Converting is for everything else: sending it to a phone, uploading it, editing it, keeping it playable on the next device.

How to tell which kind you have

• In VLC: open the file, then Tools → Codec Information (Ctrl+J). The Codec line names what is inside: "DivX", "Xvid", "MPEG-4 Video", "Motion JPEG", "H264".
• From the size: Motion JPEG and DV are large — a minute of 720p Motion JPEG is around 100 MB, against 15 to 20 MB for DivX, Xvid or H.264.
• You do not need to know. The converter reads all of them the same way.

How to convert AVI to MP4

1. Open AVI to MP4
2. Drop in the AVI, or click to choose it. Up to 20 at once; they run one after another
3. Leave the settings as they are unless the file is going somewhere that needs it smaller
4. Download the MP4

The first video conversion downloads the conversion engine into your browser; after that it is cached. Conversion runs on your own computer, so a family video or a work recording never leaves it, and a slow connection does not slow it down.

Four kinds of AVI, measured

We cut the same one-minute 1280×720 scene from the Blender Foundation's Big Buck Bunny and saved it as AVI in the four forms above, then converted each on the AVI to MP4 page with the default settings.

Every MP4 came out as H.264 (High profile) video at 1280×720 with AAC stereo sound at 192 kbps, the same length as its AVI to within 0.02 seconds, and played in Chrome — which had refused every one of the AVIs. The Motion JPEG file shrank to about a fifteenth of its size, because Motion JPEG compresses each frame on its own while H.264 stores mostly what changes between frames.

Measured on 23 October 2026 in Chrome on a laptop with an Intel Core i7-1165G7 and 16 GB of memory, timed from choosing the file to the download being ready, after the engine's one-time download. For the quality of the picture, the AVI to MP4 page has a full-length test: the whole film, ten minutes at 720p, scored 91.8 out of 100 on VMAF against the original.

What converting does not do

• It re-encodes every AVI, including H.264 ones. H.264 inside an AVI could in principle be moved into an MP4 without re-encoding, which would take seconds and lose nothing. This converter does not do that yet, so an H.264 AVI takes as long as the others and goes through one more round of compression.
• It cannot add detail. An old DivX film or a camera clip looks the same afterwards, on more devices.
• Each file can be up to about 667 MB. That covers most home videos and camera clips; a long Motion JPEG recording or a DV capture can be larger.
• Interlaced DV and TV material stays interlaced — combing on moving edges is kept, not removed.