Does converting M4A to AAC lose quality?

No. M4A is just a container for AAC audio. The FFmpeg command generated here uses -c:a copy (stream copy), which extracts the AAC bitstream without any re-encoding. The output .aac file is bit-for-bit identical to the audio data inside your M4A file.

What is the difference between M4A and AAC?

AAC is the audio codec (the compressed data). M4A is an MPEG-4 container format (.m4a extension) that wraps an AAC stream along with optional metadata (artist, album art, etc.). A raw .aac file contains only the audio bitstream with no container — useful when another tool or container needs direct AAC input.

What is the FFmpeg command for M4A to AAC?

The command is: ffmpeg -i input.m4a -c:a copy output.aac. The -c:a copy flag tells FFmpeg to copy the audio stream as-is, skipping re-encoding. This is the fastest and highest-quality approach since AAC is already the codec inside M4A.

Is my M4A file uploaded anywhere?

No. The metadata inspector uses the Web Audio API entirely in your browser. Your file is read into browser memory only and is never transmitted to any server. Refreshing the page clears all data.

Will the raw AAC file keep metadata tags?

Raw AAC files (.aac) have limited metadata support compared to M4A containers. Most players read the basic stream properties but may not display artist or album tags. If metadata preservation is important, consider keeping the M4A format or remuxing to another container like .m4a or .mp4 that supports ID3 / iTunes tags.

Can I convert multiple M4A files at once?

Yes, using a shell loop. On Linux/macOS: for f in *.m4a; do ffmpeg -i "$f" -c:a copy "${f%.m4a}.aac"; done. On Windows PowerShell: Get-ChildItem *.m4a | ForEach-Object { ffmpeg -i $_.FullName -c:a copy ($_.BaseName + ".aac") }

Why is the stream-copy command so fast?

Because no decoding or encoding takes place. FFmpeg reads the AAC packets from the M4A container and writes them directly to the output file. Processing speed is limited only by disk I/O, not CPU. A 100 MB M4A typically finishes in under a second on any modern machine.

M4A to AAC Audio Converter

Drop an M4A file to inspect its metadata, then copy the FFmpeg command that extracts the raw AAC stream without re-encoding — perfect quality, instantly.

Inspect M4A Metadata

Drop an M4A file to read its properties. Nothing is uploaded.

Drop M4A file here or click to browse M4A, AAC, MP3, WAV, OGG accepted

FFmpeg Command Generator

M4A already contains AAC audio. The command below uses -c:a copy (stream copy) — no re-encoding, no quality loss, nearly instant.

Single File

ffmpeg -i input.m4a -c:a copy output.aac

Batch Convert (Linux / macOS)

for f in *.m4a; do ffmpeg -i "$f" -c:a copy "${f%.m4a}.aac"; done

Batch Convert (Windows PowerShell)

Get-ChildItem *.m4a | ForEach-Object { ffmpeg -i $_.FullName -c:a copy ($_.BaseName + ".aac") }

Install FFmpeg free at ffmpeg.org. Replace input.m4a with your actual filename.

Drop an M4A file on the left to inspect its metadata

No file is uploaded — everything runs in your browser

M4A vs. Raw AAC — At a Glance

Property	M4A	Raw AAC (.aac)
Container	MPEG-4 (.m4a)	None (raw bitstream)
Audio Codec	AAC (same)	AAC (same)
Metadata (tags)	Full iTunes tags	Limited / none
File Size	Slightly larger	Slightly smaller
Seekable	Yes	Depends on player
Best For	General playback, Apple devices	Direct muxing into video, broadcast

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Summary

Drop an M4A file to inspect its metadata, then copy the FFmpeg command that extracts the raw AAC stream without re-encoding — perfect quality, instantly.

How it works

Drop an M4A file onto the inspector panel (or click to browse).
The Web Audio API reads the file's sample rate, duration, and channel count locally — nothing is sent to a server.
Copy the generated FFmpeg stream-copy command.
Run the command in your terminal to extract the raw AAC file.
Verify the output .aac file plays correctly before deleting the original M4A.

Use cases

Extract raw AAC audio from iTunes purchases or Apple Music downloads for use in AAC-native players.
Prepare AAC streams for direct injection into MP4 video containers without re-encoding.
Strip the M4A wrapper for devices or software that require a raw .aac file.
Losslessly remux AAC audio for use in broadcast or streaming workflows.
Batch-extract AAC from a large M4A library with a one-line shell loop.
Check an M4A file's sample rate and channel count before any processing step.
Verify that an M4A file contains a standard AAC stream before container remux.
Generate a ready-to-paste FFmpeg stream-copy command without memorizing its flags.

Frequently Asked Questions

Last updated: 2026-09-22 · Reviewed by Nham Vu