Turn an AVI your phone or TV refuses into an MP4 it plays, no sharper than the original.
Converting AVI to MP4 takes video out of an old Windows container and puts it in one that phones, browsers and smart TVs actually open. The picture is copied across when MP4 can hold its codec and re-encoded to H.264 when it cannot. It cannot look better than the AVI you started with.
Transfers use HTTPS, and files converted on the free tier are deleted after 24 hours, so the result is not a long-term archive. Quality depends on the source file, so open the MP4 file once before you share it.
AVI (Audio Video Interleave)
A container Microsoft introduced in 1992 with Video for Windows. It usually holds older codecs such as DivX, Xvid, Motion JPEG or DV, with MP3 or uncompressed PCM audio, and it predates streaming and modern compression features.
MP4 (MPEG-4 Part 14)
The container used by current phones, cameras and streaming services. It was designed for codecs with reordered frames, variable frame rates and playback that starts before the download finishes, three things the older AVI structure handles awkwardly.
An 8-second 960 × 540 clip with sound, saved as AVI, converted on indox.org
An AVI that will not open usually holds DivX, Xvid or DV video that your device has no decoder for. The conversion runs on indox infrastructure, so nothing is installed on your computer, and a single file needs no account.
If you are clearing a drive of camcorder captures or old downloads, drop several AVI files on the box together, or import them from Dropbox, Google Drive or a URL. Each file gets its own MP4 result.
DV and Motion JPEG captures are heavy files. The upload box shows the size limit before you add one; signing in raises it, and a paid plan does not change it. Once the job starts, a progress bar shows it and you can cancel.
Drop the AVI on the box, choose it from your device, or import it from Dropbox, Google Drive or a URL. A download that was cut off may convert only partly, so use a complete file.
Check that MP4 is set as the output format, then start the job. A progress bar shows it running, and you can cancel if you added the wrong clip.
Save the MP4 and play a part with motion and speech. Comb-like lines on moving objects come from interlaced camcorder footage, and sound that drifts out of step can point to a damaged AVI.
You get an MP4 made from an AVI that current phones and televisions would not open. The picture and sound are copied across when MP4 can hold their codecs, and a picture it cannot hold is re-encoded to H.264. It cannot look better than the source. Nothing is installed, a single file needs no account, and you can download the result or share it with a link.
The upload box shows the live size limit before you add a file. Signing in raises it; a paid plan does not change it.
AVI in, MP4 out. Pick another output on the converter if you need a different format.
Files are encrypted in transit over HTTPS and processed on indox infrastructure.
Free-tier files are kept for 24 hours after the job finishes, then deleted automatically.
| What you see | Why | What to do |
|---|---|---|
| The MP4 still will not play on a phone or TV | The container is now MP4, but a copied picture keeps its original codec, which the device may not decode | Check the codec of the original AVI and compare it with what your device supports |
| Moving edges show comb-like lines | The footage is interlaced, and no deinterlacing is applied during conversion | Switch on deinterlacing in your player while you watch |
| Sound is missing or out of step | The AVI may be damaged or incomplete, or its audio may not fit MP4 | Get a complete copy of the AVI and convert it again |
| A second sound track is missing | Only one audio stream is picked automatically, the one with the most channels | Keep the AVI if you need every track |
iPhone and Mac video that plays anywhere
Video for phones, TVs and editors
Browser recordings you can share
The sound from a video
| Compared on | AVI | MP4 |
|---|---|---|
| Origin | A subtype of RIFF, developed by Microsoft and IBM for Windows 3.1 | The MPEG-4 file format, which owes a debt to QuickTime |
| Standard | A proprietary format whose documentation is freely available | An ISO/IEC standard |
| Browser support | Not broadly supported by browsers | Supported by all browsers |
| What it holds | Audio and video interleaved in one file | An object-based design for audio-visual scenes, text and graphics |
Facts checked on October 16, 2026
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Most often the device lacks a decoder for the codec inside, not for AVI itself. AVI is only a wrapper, and its usual contents (DivX, Xvid, Motion JPEG, DV) are formats that phones, browsers and many smart TVs dropped or never supported. Converting moves them into an MP4, and a picture that MP4 cannot hold becomes H.264. Check that your device decodes the codec the picture ends up in.
Not when the picture is copied across, because nothing is re-encoded. When MP4 cannot hold it, the picture is decoded and compressed again as H.264, which costs a little detail. What you will not get is an improvement: softness and artefacts from the original stay.
It depends on the codec inside. When the video is copied (MPEG-4 such as DivX and Xvid, or Motion JPEG), the size stays close to the AVI. When it is re-encoded to H.264, as DV is, the size changes and is often smaller, because H.264 is a more efficient codec, but nothing guarantees it.
Yes, in many cases. The video is copied without re-encoding when it is MPEG-4 (DivX and Xvid) or Motion JPEG, and the audio is copied as it is. Other codecs, such as DV, are re-encoded to H.264. A copied picture keeps its original codec, so a device that cannot decode it will still refuse the MP4.
Those lines are interlacing from the original recording. DV camcorders and television captures stored each frame as two fields taken a fraction of a second apart, which old tube televisions blended naturally. On a progressive screen the fields show as a comb pattern wherever something moves. Deinterlacing removes it, at some cost in vertical sharpness.
As an original, yes, as an everyday format, no. Keep the untouched AVI if it is a first-generation capture, since every re-encode loses a little and a better conversion may be possible later. For watching, sharing and uploading, MP4 is the practical choice because support for AVI's codecs keeps shrinking with each new device.