What happens when you convert AIFC to MP4
- MP4 is a video format. The audio is encoded as AAC audio, and by default the file has no picture.
- Tick "Add a black video track" if the MP4 is going to YouTube or another site that rejects audio-only video.
How to convert AIFC to MP4 online
- Press "Choose AIFC files" and select one or more files, or drag them onto the box. You can add files of any size your device can hold in memory.
- Adjust the settings if you need to: resolution and quality control the size of the result. The defaults suit most people.
- Press "Convert to MP4". The first audio or video conversion downloads the converter engine, about 32 MB, which your browser then keeps for next time.
- Save each MP4 with its download button. Close the tab and every trace of the files is gone from memory.
Why convert AIFC to MP4?
AIFC files usually come from older Mac software and some sound effect libraries. People convert them to MP4 because MP4 with H.264 plays on every phone, laptop, smart TV and website, and it is what YouTube, Instagram, TikTok and WhatsApp expect.
In short, AIFC is good at what it was made for, and MP4 is the more practical choice when the file has to play, upload or edit somewhere else. AIFC plays in some Mac apps; browsers do not play it, while MP4 plays in every browser, phone and smart TV.
How to convert AIFC to MP4 on Windows, Mac, iPhone and Android
On Windows
Open this page in Chrome, Edge or Firefox, drag your AIFC files in from File Explorer, and press Convert. Each MP4 is saved to your Downloads folder. If you prefer a desktop program, VLC can also convert AIFC to MP4: choose Media, then Convert / Save.
On a Mac
Safari, Chrome and Firefox all work. Drag the AIFC files from Finder onto the drop zone and the MP4 files land in Downloads.
On iPhone and iPad
Open the page in Safari and tap Choose AIFC files. You can pick from Photos or from the Files app. The converted MP4 appears in Files, in the Downloads folder; to put it in your photo library, open it there, tap Share and choose Save Video.
On Android
Open the page in Chrome, tap Choose AIFC files and pick them from Files or your gallery. The MP4 is saved to the Download folder, where any file manager can find it. Keep the screen on while a long video converts, because Android may pause a tab in the background.
Best settings for AIFC to MP4
Leave Resolution on Keep original and Quality on Standard if the video only needs to change container: that is what lets the tool copy the H.264 stream straight into the MP4, which is fast and loses nothing.
If the file is too big, change either setting and the video is re-encoded with H.264. Quality uses the CRF scale: High is 20, Standard 23 and Smaller file 28. As a rule of thumb each step of about 6 on that scale halves or doubles the size. Dropping from 1080p to 720p usually saves more than lowering the quality, and it also makes the conversion much faster.
AIFC vs MP4: the differences
| AIFC | MP4 | |
|---|---|---|
| Full name | Audio Interchange File Format, Compressed | MPEG-4 Part 14 video |
| Type | audio | video |
| Created by | Apple | the Moving Picture Experts Group |
| First released | 1991 | 2001 |
| Compression | Lossy or lossless | Lossy |
| Usually contains | PCM or compressed codecs such as IMA ADPCM | H.264 or H.265 video with AAC audio |
| In a browser | plays in some Mac apps; browsers do not play it | plays in every browser, phone and smart TV |
| Common uses | older Mac software and some sound effect libraries | phone videos, YouTube uploads, social media and streaming |
| MIME type | audio/aiff | video/mp4 |
About AIFC and MP4 files
What is an AIFC file?
AIFC is the variant of AIFF that allows compressed audio. Few modern programs write it, so most people meet it in old sound libraries.
What is an MP4 file?
MP4 is the most widely supported video format, and H.264 video with AAC audio inside it plays on essentially every device made in the last fifteen years.
AIFC to MP4 not working? Common problems
- The conversion is slow. Audio and container changes take seconds, but re-encoding video runs on your own processor. Lower the resolution to 720p, close other tabs, and keep the device plugged in.
- The tab stops or reloads on a very large file. Browsers limit how much memory one tab can use, around 2 GB and less on phones. Split long recordings or convert them on a computer.
- The MP4 will not play on an old device. Try the other formats offered for AIFC, or choose 720p, which older players handle more reliably.
Convert AIFC to MP4 with ffmpeg
This converter runs ffmpeg inside your browser. If you would rather use the ffmpeg command line on your own computer, this command produces an equivalent MP4 with the same kind of settings:
ffmpeg -i input.aifc -c:v libx264 -crf 23 -preset veryfast -c:a aac -b:a 128k -movflags +faststart output.mp4Replace input.aifc with the name of your file. For a whole folder of AIFC files, run the command in a loop, or drop them all on the converter above, which processes them one after another.
AIFC to MP4 converter FAQ
Will I lose quality converting AIFC to MP4?
A little. Both formats are lossy, so re-encoding compounds the loss slightly. Keep the default quality or higher and the difference is rarely noticeable.
Why is the MP4 a different size from the AIFC?
Without a picture, the MP4 is about the size of the audio. Adding a black video track adds a little, because a still black frame compresses to almost nothing.
Are my AIFC files uploaded anywhere?
No. The conversion runs inside this browser tab using ffmpeg compiled to WebAssembly, so your files stay on your device. You can disconnect from the internet after the page and converter engine have loaded and it still works.
Can I convert several AIFC files to MP4 at once?
Yes. Select or drop as many files as you like; they are converted one after another and each gets its own download button.
How do I open an MP4 file?
MP4 plays in every browser, phone and smart TV. MP4 is common for phone videos, YouTube uploads, social media and streaming.
Is this AIFC to MP4 converter free?
Yes. There is no sign-up, no watermark and no limit on how many files you convert. The site is paid for by advertising, and because conversions run on your device there is no server cost per file.
Can I convert AIFC to MP4 on my phone?
Yes. The converter works in Safari on iPhone and iPad and in Chrome on Android. Long HD videos convert more slowly on a phone than on a computer.