AAC to MP3 via CLI

Encode AAC to MP3 with ffmpeg and libmp3lame.

Packages to install

Only ffmpeg is required. libmp3lame encodes MP3 at a constant bitrate.

ffmpeg

sudo apt-get update
sudo apt-get install -y ffmpeg

How to run the command

ffmpeg -i input.aac -vn -c:a libmp3lame -b:a 192k output.mp3. -vn drops extra streams so the result is audio-only.

ffmpeg -y -i input.aac -vn -c:a libmp3lame -b:a 192k output.mp3

Dockerfile example

Build a minimal Ubuntu image with the required packages and run the conversion inside the container.

FROM ubuntu:24.04

RUN apt-get update && \
    apt-get install -y --no-install-recommends \
        ffmpeg && \
    rm -rf /var/lib/apt/lists/*

WORKDIR /work

docker build -t aac-to-mp3 .
docker run --rm -v "$PWD:/work" -w /work aac-to-mp3 \
  ffmpeg -y -i input.aac -vn -c:a libmp3lame -b:a 192k output.mp3

Example commands

Run these locally after installing the packages, or inside the container from the Dockerfile.

ffmpeg -y -i input.aac -vn -c:a libmp3lame -b:a 192k output.mp3

ffmpeg -y -i track.aac -vn -c:a libmp3lame -b:a 192k -ar 44100 -ac 2 track.mp3