What happens when you convert AC3 to AAC
- The audio is decoded and written as AAC at 192 kbps in an ADTS stream.
- Going from one lossy format to another adds a small generation loss. Choose a bitrate at least as high as the source to keep it inaudible.
- Surround channels are kept where the target supports them and mixed to stereo where it does not.
How to convert AC3 to AAC online
- Press "Choose AC3 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: the bitrate controls quality and size. The defaults suit most people.
- Press "Convert to AAC". The first audio or video conversion downloads the converter engine, about 32 MB, which your browser then keeps for next time.
- Save each AAC with its download button. Close the tab and every trace of the files is gone from memory.
Why convert AC3 to AAC?
AC3 files usually come from DVD and Blu-ray soundtracks and TV broadcasts. People convert them to AAC because raw AAC streams are what some broadcasters, podcast tools and hardware players ask for.
In short, AC3 is good at what it was made for, and AAC is the more practical choice when the file has to play on another device or app. Most browsers do not play AC3; Safari on Apple devices does, while AAC plays in all current browsers and on Apple and Android devices.
How to convert AC3 to AAC on Windows, Mac, iPhone and Android
On Windows
Open this page in Chrome, Edge or Firefox, drag your AC3 files in from File Explorer, and press Convert. Each AAC is saved to your Downloads folder. If you prefer a desktop program, VLC can also convert AC3 to AAC: choose Media, then Convert / Save.
On a Mac
Safari, Chrome and Firefox all work. Drag the AC3 files from Finder onto the drop zone and the AAC files land in Downloads.
On iPhone and iPad
Open the page in Safari and tap Choose AC3 files. You can pick from Photos or from the Files app. The converted AAC appears in Files, in the Downloads folder.
On Android
Open the page in Chrome, tap Choose AC3 files and pick them from Files or your gallery. The AAC 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 AC3 to AAC
AAC is a lossy format, so the bitrate decides both the sound quality and the file size. Size grows in a straight line with bitrate: double the bitrate and the file doubles.
| Bitrate | Size per minute | Good for |
|---|---|---|
| 320 kbps | about 2.4 MB | the highest quality, for music you will keep |
| 256 kbps | about 1.9 MB | excellent music quality |
| 192 kbps | about 1.4 MB | the default: transparent for most listeners |
| 128 kbps | about 1.0 MB | good for music on the go and for podcasts |
| 96 kbps | about 0.7 MB | speech and audiobooks |
| 64 kbps | about 0.5 MB | voice notes and spoken word only |
The AC3 was already compressed, so pick a bitrate at least as high as the original. Going higher does not add quality back, it only makes the file bigger.
AC3 vs AAC: the differences
| AC3 | AAC | |
|---|---|---|
| Full name | Dolby Digital | Advanced Audio Coding |
| Type | audio | audio |
| Created by | Dolby Laboratories | the Moving Picture Experts Group |
| First released | 1991 | 1997 |
| Compression | Lossy | Lossy |
| Usually contains | Dolby Digital, up to 5.1 channels | AAC audio in a raw ADTS stream |
| In a browser | most browsers do not play it; Safari on Apple devices does | plays in all current browsers and on Apple and Android devices |
| Common uses | DVD and Blu-ray soundtracks and TV broadcasts | iTunes and Apple Music, YouTube audio and streaming |
| MIME type | audio/ac3 | audio/aac |
About AC3 and AAC files
What is an AC3 file?
AC3 carries surround sound for DVDs and broadcast TV, up to six channels. Converting it to a stereo format mixes those channels down.
What is an AAC file?
AAC was designed as the successor to MP3 and sounds better at the same bitrate, especially below 128 kbps. A bare .aac file is a raw stream with no chapters or cover art; the same audio in a container is usually called M4A.
AC3 to AAC 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.
- Song titles are missing. Tags such as title and artist are copied when AAC can store them, but cover art is not carried over.
Convert AC3 to AAC 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 AAC with the same kind of settings:
ffmpeg -i input.ac3 -vn -c:a aac -b:a 192k -f adts output.aacReplace input.ac3 with the name of your file. For a whole folder of AC3 files, run the command in a loop, or drop them all on the converter above, which processes them one after another.
AC3 to AAC converter FAQ
Will I lose quality converting AC3 to AAC?
A little. Both formats are lossy, so re-encoding compounds the loss slightly. Keep the default bitrate or higher and the difference is rarely noticeable.
Why is the AAC a different size from the AC3?
It depends on the settings. At the defaults, the AAC usually comes out close in size to the AC3; lower the bitrate for a smaller file.
Are my AC3 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 AC3 files to AAC 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 AAC file?
AAC plays in all current browsers and on Apple and Android devices. AAC is common for iTunes and Apple Music, YouTube audio and streaming.
Is this AC3 to AAC 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 AC3 to AAC on my phone?
Yes. The converter works in Safari on iPhone and iPad and in Chrome on Android. Converted files are saved to the Downloads folder.