What is an AC3 file?
AC3 stands for Dolby Digital. It was created by Dolby Laboratories and first released in 1991. AC3 carries surround sound for DVDs and broadcast TV, up to six channels. Converting it to a stereo format mixes those channels down.
| Type | audio |
|---|---|
| Compression | Lossy |
| Usually contains | Dolby Digital, up to 5.1 channels |
| In a browser | most browsers do not play it; Safari on Apple devices does |
| Common uses | DVD and Blu-ray soundtracks and TV broadcasts |
| MIME type | audio/ac3 |
Which format should you convert AC3 to?
- AC3 to MP3 to play on any device, car stereo or website.
- AC3 to WAV to edit in an audio editor or burn to CD.
AC3 is already lossy, so converting it to a lossless format makes the file bigger without improving it; pick a lossless target only if a program requires one.
How to open an AC3 file
Whether an AC3 file opens with a double click depends on the device. Here is what works on each, without buying software:
| Windows | Films and TV and Media Player open the common formats; VLC opens almost any audio file, AC3 included. |
|---|---|
| Mac | QuickTime Player opens formats Apple supports; VLC or IINA open the rest. |
| iPhone and iPad | The Files app plays formats Apple supports. For others, a player such as VLC for iOS, or converting the file here, is the easiest route. |
| Android | Most gallery and music apps play the common formats; VLC for Android plays almost everything. |
| Web browser | Most browsers do not play AC3; Safari on Apple devices does. |
Want the technical details? See what a .ac3 file is, with its MIME type, file signature and a viewer.
AC3 compared with other audio formats
How AC3 stacks up against the formats people most often convert it to or from:
| Format | Compression | Usually contains | Released | Best for |
|---|---|---|---|---|
| AC3 | Lossy | Dolby Digital, up to 5.1 channels | 1991 | DVD and Blu-ray soundtracks and TV broadcasts |
| MP3 | Lossy | MP3 audio, typically 128 to 320 kbps | 1993 | music libraries, podcasts and anything that has to play everywhere |
| WAV | Lossless | uncompressed PCM, usually 16-bit at 44.1 or 48 kHz | 1991 | recording, editing, sound effects and CD audio |
| M4A | Either | AAC, or ALAC for lossless files | 2001 | iTunes purchases, iPhone voice memos and Apple Music downloads |
| FLAC | Lossless | FLAC lossless audio, up to 32-bit and 655 kHz | 2001 | CD rips, hi-res music stores and audio archives |
How to use the AC3 converter
- Choose the format you want in the Convert to menu.
- Drop your AC3 files on the box, or press Choose AC3 files. Several files can go in at once.
- Adjust the settings if you need to; the defaults suit most people.
- Press Convert and save each file with its Download button. Nothing is uploaded at any point.
Tips for converting AC3 files without losing quality
AC3 is lossy, so some detail was already discarded when the file was made. Converting it cannot bring that back. Converting to a lossless format preserves what is left exactly but makes the file larger; converting to another lossy format adds a small extra loss, which is invisible at sensible settings.
- Keep a lossless master. If you have WAV, FLAC, AIFF or ALAC, keep it, and make lossy copies such as MP3 or AAC from it when you need them.
- Avoid converting one lossy format into another more than once. Each MP3, AAC or OGG encode throws away a little more, and the losses add up.
- Match the bitrate to the content: 192 kbps and up for music, 96 to 128 kbps for podcasts, 64 kbps for voice notes.
- Stick to 44.1 kHz for music and 48 kHz for audio that goes with video; resampling between them is harmless but pointless.
Convert AC3 files from the command line
Everything this page does can also be done in a terminal. The most common AC3 conversion, to AAC, looks like this with ffmpeg:
ffmpeg -i input.ac3 -vn -c:a aac -b:a 192k -f adts output.aacChange the output extension to pick another format. The converter above runs the same ffmpeg engine inside your browser, so you get the result without installing anything.
AC3 converter FAQ
What is an AC3 file?
AC3 stands for Dolby Digital, an audio format created by Dolby Laboratories in 1991. AC3 carries surround sound for DVDs and broadcast TV, up to six channels. Converting it to a stereo format mixes those channels down.
How do I open an AC3 file?
Most browsers do not play AC3; Safari on Apple devices does. If the program you need will not open it, convert it to a more widely supported format above.
What is the most common AC3 conversion?
AC3 to AAC is the conversion people search for most. The audio is decoded and written as AAC at 192 kbps in an ADTS stream.
Does converting AC3 files here upload them?
No. Every conversion on this page runs inside your browser, so your AC3 files never leave your device.
Is the AC3 converter free?
Yes. There is no sign-up and no watermark, and no limit on how many AC3 files you convert. The site is supported by advertising.
Can I convert AC3 files on iPhone or Android?
Yes. Open this page in Safari on iPhone and iPad, or in Chrome on Android, choose your AC3 files and download the results to your Downloads folder.
Can I convert several AC3 files at once?
Yes. Drop as many as you like; they are converted one after another, each with its own download button.