AVI to MP4 Converter
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Convert AVI to MP4 online
Convert AVI to MP4 to bring an old video into the present. The dated codec inside the AVI is replaced with H.264 at CRF 23, the audio becomes AAC, and the result plays on every phone, browser, and TV made in the last fifteen years.
When should you convert AVI to MP4?
- Rescue footage from an old camcorder or DVD rip
- Play a legacy file on a phone or a smart TV
- Reduce the size of a large, inefficiently encoded archive
- Upload old footage to a modern platform
Before you convert
Usually a large size reduction
AVI's old codecs are far less efficient than H.264, so this is one of the few conversions where the file typically gets substantially smaller at the same visual quality.
It cannot repair the source
Interlacing, low resolution, and compression artifacts in the original AVI are encoded faithfully into the MP4.
What happens to your file
AVI to MP4 is a full re-encode, not a container swap: the video is decoded and re-compressed with libx264 (H.264) at CRF 23, preset medium, and the audio is re-encoded to AAC at 192 kbps. The MP4 index is moved to the front of the file (+faststart) so it can start playing before the whole download finishes, and pixels are written as yuv420p for maximum device compatibility.
Settings this conversion runs with
| Engine | ffmpeg |
|---|---|
| Video codec | libx264 (H.264) |
| Video quality | CRF 23, preset medium |
| Audio codec | AAC |
| Audio bitrate | 192 kbps |
What changes
- The AVI picture is decoded and re-compressed with libx264 (H.264), so this is a generation loss: the output is built from an already-compressed source, not from the original camera data. Converting AVI to MP4 and back will soften the clip a little more each time.
- Only one video and one audio stream reach the MP4 file. Additional audio languages, embedded subtitle tracks, and chapter markers are not carried across.
About AVI and MP4 files
AVI video
Strengths
- widely recognized
- simple container
Limitations
- large files
- dated format
MP4 video
Strengths
- plays almost everywhere
- good quality-to-size
- widely supported
Limitations
- lossy compression
- less flexible than MKV
AVI vs MP4
| Format | AVI | MP4 |
|---|---|---|
| Compression | Lossy | Lossy |
| Transparency | — | — |
| Best for | legacy Windows video, older recordings | streaming and sharing, playback on any device |
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Frequently asked questions
- Does converting AVI to MP4 re-encode the file?
- AVI to MP4 is a full re-encode, not a container swap: the video is decoded and re-compressed with libx264 (H.264) at CRF 23, preset medium, and the audio is re-encoded to AAC at 192 kbps. The MP4 index is moved to the front of the file (+faststart) so it can start playing before the whole download finishes, and pixels are written as yuv420p for maximum device compatibility.
- What should you know before converting AVI to MP4?
- The AVI picture is decoded and re-compressed with libx264 (H.264), so this is a generation loss: the output is built from an already-compressed source, not from the original camera data. Converting AVI to MP4 and back will soften the clip a little more each time.
- Is this AVI to MP4 converter free?
- Yes. You can convert AVI to MP4 online for free, with no account and no watermark.
- Do I need to install software or sign up?
- No. Use the converter from your browser without installing software or creating an account. Files are uploaded to our servers for processing.
- Will converting AVI to MP4 reduce quality?
- MP4 uses lossy compression, so the file can get smaller while some visual quality may change.
- Are my files safe?
- Yes. Files are processed only to complete the conversion and are auto-deleted after 2 hours. We never share them.