Free online ALAC to AC3 converter

DVD authoring tools, AV receivers, televisions, and video editors may require Dolby Digital AC3 instead of Apple Lossless files. Converting the track creates a compatible, lossy AC3 stream with a suitable channel layout, sample rate, and bitrate.

What the ALAC format is

ALAC (Apple Lossless Audio Codec) compresses audio without changing the original PCM samples. It is used mainly in Apple Music, iTunes, QuickTime, GarageBand, Logic Pro, and other Apple-compatible software, usually inside .m4a files and sometimes .caf files.

Because ALAC is lossless, it is suitable for archiving and editing: decoding it does not discard audio information. Its lossless compression does not help when a device or authoring program specifically requires Dolby Digital AC3.

What the AC3 format is

AC3, also called Dolby Digital, is a lossy audio codec developed by Dolby Laboratories for DVDs, broadcast, video files, older AV receivers, home-theater systems, and authoring workflows. It supports mono, stereo, and multichannel layouts, including 5.1 surround sound.

AC3 is useful when a playback or authoring system has a required Dolby Digital input or when a separate .ac3 stream is needed. Encoding discards audio information, so AC3 should not replace the original ALAC archive. At comparable perceived quality, newer codecs can be more size-efficient, but AC3 remains common in legacy and disc-based workflows.

How to convert ALAC to AC3

Using FFmpeg

FFmpeg decodes ALAC and encodes AC3 on Windows, macOS, and Linux. Install a current FFmpeg build, open a terminal in the folder containing the source file, and run:

ffmpeg -i input.m4a -vn -c:a ac3 -ar 48000 -b:a 448k output.ac3

This command reads input.m4a, ignores any video stream with -vn, resamples the audio to 48 kHz, encodes it as AC3 at 448 kbps, and writes a separate raw AC3 stream. Replace the filenames with the actual paths; quote paths containing spaces, for example "My audio.m4a".

Choose the bitrate to match the target:

• 192 kbps is commonly suitable for stereo.
• 384 or 448 kbps is commonly used for 5.1-channel video and DVD workflows.
• 640 kbps is the highest commonly supported AC3 bitrate, but a particular disc or device specification may impose a lower limit; DVD workflows commonly use no more than 448 kbps.

Use 48 kHz for DVD and most video projects. To inspect the source before encoding, run:

ffprobe -v error -select_streams a:0 -show_entries stream=codec_name,sample_rate,channels,channel_layout -of default=noprint_wrappers=1 input.m4a

If the file contains multiple audio streams, select the required one explicitly:

ffmpeg -i input.m4a -map 0:a:0 -vn -c:a ac3 -ar 48000 -b:a 448k output.ac3

For a video file that needs AC3 inside the video rather than as a separate .ac3 stream, place it in a compatible container:

ffmpeg -i video.mkv -map 0:v:0 -map 0:a:0 -c:v copy -c:a ac3 -ar 48000 -b:a 448k output.mkv

Do not use -c:a copy when converting: stream copying preserves the source ALAC bitstream instead of encoding AC3.

Using 101convert.com

On 101convert.com, open the audio converter, upload the file containing the ALAC track, choose AC3 as the output format, start the conversion, and download the resulting file. This option requires no software installation. If the converter exposes bitrate or sample-rate settings, select values accepted by the target device or authoring specification.

Quality and compatibility limits

ALAC-to-AC3 conversion is lossy. Converting the result back to ALAC cannot restore information removed during AC3 encoding, so retain the original ALAC file and use AC3 only as a delivery or playback copy.

Preserve the source channel layout unless the target requires stereo. Downmixing 5.1 to stereo changes the mix and can affect dialogue, effects, and channel balance; test the result on the intended equipment. Confirm that the receiving program accepts the chosen AC3 bitrate, sample rate, channel count, and either a separate .ac3 file or the selected video container.