Step 1: Transfer your AVI files using the button above or by slide and deposit.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Retrieve your converted MP4 files.
AVI to MP4 Conversion FAQ
How do I re-encode AVI to MP4 without losing video quality?
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Upload your AVI file and the converter runs a CRF-based re-encode targeting visually-lossless MP4 output (CRF 18 by default, lower values = larger file / higher quality). The codec is chosen to match the MP4 container — H.264 for broad-compat MP4, H.265 for size-efficient MKV, VP9 for WebM, AV1 for newer pipelines. AVI files predate modern codecs: expect MPEG-4 Part 2 (DivX/Xvid), Motion JPEG or raw uncompressed frames rather than H.264. Almost every MP4 in the wild is H.264 video with AAC audio; the container also legally holds HEVC, AV1 and VP9.
My AVI footage shows comb lines on movement — will that carry into the MP4?
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It will unless you deinterlace, and AVI content very often is interlaced because the format comes from the broadcast and DVD era. Interlaced frames store two half-height fields captured a fiftieth of a second apart; on a progressive-scan phone or monitor that reads as horizontal combing on anything that moves. Turn on the deinterlace option and the encoder weaves the fields into whole progressive frames before writing the MP4. 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.
My AVI recordings are split into numbered parts — does MP4 have the same limit?
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No, and that is one of the better reasons to move. The AVI container has a practical single-file ceiling that long or high-bitrate recordings run straight into, which is exactly why old captures arrive as part1, part2, part3. MP4 has no equivalent limit, so the pieces can be rejoined into one continuous file. 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.
Can I add selectable subtitles once the file is MP4?
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Yes. AVI has no usable soft-subtitle track, so subtitles for AVI content had to be burned into the picture or shipped as a separate sidecar file. MP4 carries subtitles as their own selectable stream, so after conversion you can attach an SRT track the viewer can switch on, switch off or restyle.
My AVI has several audio tracks — do they all survive into the MP4?
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Not dependably. AVI stores multiple audio streams as first-class tracks, but MP4 playback support past the first track is inconsistent, so most players will only ever expose one. Choose the track you actually want before converting; the others are better extracted to their own files than left in a container that hides them. AVI is trivially simple, which is exactly why ancient camcorders, capture cards, DVD ripping tools and Windows-era software all still emit it. MP4 only supports one widely-honoured subtitle format (mov_text), and multi-track audio is unreliable outside desktop players.
Will the MP4 play in a browser when the AVI would not?
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Yes, and that is usually the whole reason for the conversion. An AVI embedded in a web page either shows a broken player or forces a download, because browsers ship no decoder for it. MP4 plays inline through the native HTML5 video element with no plugin and no external application. MP4 is the safest possible delivery target — every phone, browser, console, editor and Smart TV built in the last decade plays it without extra software.
Is it worth converting old AVI recordings to MP4 at all?
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For anything you intend to keep, yes. AVI belongs to an earlier generation of video tooling and the software that reads it is steadily disappearing from phones, browsers and operating systems. Moving the footage to MP4 now, while a clean decoder still exists, is the difference between an archive you can open in ten years and one you cannot.
Which video codec does the MP4 output use?
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It depends on the MP4 container. MP4 defaults to H.264 for the broadest playback support across phones, browsers, and Smart TVs. MKV defaults to H.265 / HEVC for roughly half the file size at equivalent quality. WebM defaults to VP9. The advanced options expose explicit codec choice if you need to override. MP4 is ISO/IEC 14496-14, standardised in 2001 and derived from the same QuickTime box layout MOV uses.
Will my audio track survive AVI to MP4 conversion?
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Yes. When AVI and MP4 share an audio codec (e.g. both carry AAC), audio is re-muxed with no re-encode — bit-identical. When the codecs differ, audio is transcoded to AAC / Opus / Vorbis depending on what the MP4 container supports. Multi-track audio (commentary, alternate languages) is preserved.
Can I keep the original framerate when converting AVI to MP4?
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By default yes — a 24fps AVI stays 24fps in MP4; a 60fps AVI stays 60fps. If you need to change rate (e.g. interlaced 29.97 → progressive 30, or 60 → 30 for upload limits), the framerate option handles 3:2 pulldown, deinterlacing, and frame-blending in the same encode pass.
How much will the file size change going from AVI to MP4?
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Same-codec re-mux (AVI H.264 → MP4 H.264 just changing container): nearly identical size. Codec change can swing dramatically: H.264 → H.265 typically halves the file at the same visual quality; VP9 is roughly comparable; AV1 cuts another 20-30% but is slower to encode.
Will the MP4 file play on iPhone, Android, and Smart TVs?
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MP4 / H.264 plays natively on every modern device. MOV / H.264 plays on Apple devices and most TVs but not always on older Android. MKV needs VLC on iOS. WebM is browser-first. The advanced options include a "device compatibility" preset that picks the safest MP4 codec / container for your target.
