Cut AAC

How to Cut an AAC File Online

1. Upload Your AAC File: Drag and drop or click "+ Add Files" to select your .aac file. Raw ADTS streams from YouTube extraction tools, AAC pulled from a TS/M2TS broadcast capture, FFmpeg dumps, and .aac exports from audio editors all work. Batch is supported — drop in a folder of episode rips and apply the same cut to all of them.
2. Set Start Time and Duration: Enter the start position and the segment length. Both fields accept seconds (e.g. 42.5) or HH:MM:SS.sss format (e.g. 00:00:42.500). Because AAC encodes audio in fixed blocks of 1024 samples, the smallest clean cut at 44.1 kHz is roughly 23 ms — XConvert rounds your start/end to the nearest frame boundary so playback stays in sync.
3. Adjust Output Format and Quality (Optional): The default keeps the output as raw AAC (ADTS) at the source bitrate, sample rate, and channel count. Switch to M4A wrapping if you need cover art and tags (AAC to M4A), drop to mono for voice, or re-encode at a lower bitrate (96-128 kbps for speech, 192-256 kbps for music). Leave the codec on "Unchanged" to avoid a re-encode and the small generation loss it carries.
4. Cut and Download: Click "Cut". Files process in your browser session and download individually or as a ZIP — no sign-up, no watermark, no upload to a third-party server.

Why Cut AAC Files?

AAC (Advanced Audio Coding) is the audio codec defined in MPEG-2 Part 7 (ISO/IEC 13818-7, standardised April 1997) and extended in MPEG-4 Part 3. A bare .aac file is the raw ADTS bitstream — frames concatenated with a small sync header on each one and nothing wrapping them. That makes .aac files the natural drop from streaming captures, TS broadcasts, and tools like FFmpeg's aac muxer, but they lack the metadata atoms that .m4a (the MPEG-4 container) provides. Cutting in-place keeps you in the raw stream so the result still plays in any AAC decoder without a container rewrap.

• Pulling a clip from a YouTube or stream rip — yt-dlp's --extract-audio --audio-format aac output is raw ADTS. Trimming the dead first 10 seconds of an intro before sharing keeps the file in its original codec without a re-encode.
• TS broadcast captures — over-the-air ATSC and DVB feeds carry AAC inside MPEG-2 transport streams. Demuxing produces a .aac ADTS file you can splice on frame boundaries for an archival clip.
• Removing silence from voice memos exported as AAC — many recorders save raw AAC by default. Strip the lead-in tap and trailing pause before sending to a transcriber or podcast producer.
• Game and app sound effects — Android and many cross-platform games ship sound assets as raw AAC for size; cutting a single SFX out of a longer recording avoids the container overhead of M4A.
• Bluetooth audio testing — AAC is the default Bluetooth codec on iPhone and supported on Android. A short, frame-accurate AAC test clip is handy for codec/latency QA.
• Mailing a short clip — a 90-second 128 kbps AAC clip is about 1.4 MB, comfortably under Gmail's 25 MB attachment cap and any messaging-app limit.

AAC (.aac) vs M4A vs MP3 — Format Comparison

Property	AAC (.aac, raw ADTS)	M4A (AAC-in-MP4)	MP3
Container	None — raw ADTS frames	MPEG-4 Part 14 (ISO/IEC 14496-14)	MPEG-1/2 Audio Layer III
Codec inside	AAC-LC / HE-AAC / HE-AAC v2	Usually AAC, sometimes ALAC (lossless)	MP3
Metadata / tags	Limited (ID3 sometimes works, not standard)	Full iTunes-style tags, cover art, chapters	ID3v1 / ID3v2
Standardised	AAC: 1997 (MPEG-2) / 1999 (MPEG-4)	MP4 container: 2003	1993
Typical use	Stream rips, broadcast TS demuxes, FFmpeg output	iTunes, Apple Music, Voice Memos, audiobooks	Universal distribution, podcasts, legacy players
Frame size	1024 samples (or 960) per AAC block	Same — AAC inside	1152 samples per MP3 frame
Lossless cut accuracy at 44.1 kHz	~23 ms (frame-aligned)	~23 ms (frame-aligned)	~26 ms (frame-aligned)
Compression efficiency vs MP3	~20% smaller at equal perceived quality	Same — AAC is the codec	Baseline
Best when	You need a portable raw stream	You want metadata, art, chapters, Apple compatibility	You need playback everywhere, including a 2008 car stereo

AAC Bitrate and Profile Quick Guide

Profile / bitrate	Typical use	1-minute size	Notes
HE-AAC v2 @ 24-48 kbps	Streaming radio, voice	~0.2-0.4 MB	Adds SBR + Parametric Stereo for low-bitrate efficiency
HE-AAC @ 64 kbps	Low-bandwidth music streams	~0.5 MB	AAC-LC + Spectral Band Replication
AAC-LC @ 96 kbps stereo	Podcasts, lectures	~0.7 MB	Light high-frequency softness
AAC-LC @ 128 kbps stereo	Default for many ripping apps, broadcast	~0.9 MB	Roughly equal in quality to a 160-192 kbps MP3
AAC-LC @ 256 kbps stereo	iTunes Plus / Apple Music delivery (since 2007)	~1.9 MB	Effectively transparent for most listeners
AAC-LC @ 320+ kbps	Archival / mastering reference	~2.3 MB	Diminishing returns above 256 kbps

Frequently Asked Questions

Will cutting reduce my AAC file's quality?

If you keep the output as AAC at the same bitrate, sample rate, and channel count as the source, the cut is performed on ADTS frame boundaries — each AAC frame is a self-contained 1024-sample block that doesn't depend on its neighbours, so frames can be sliced out without decoding. At worst you lose up to one frame (~23 ms at 44.1 kHz) of accuracy at each cut. If you re-encode to a lower bitrate or change the sample rate, that's a separate lossy step on top of the cut. Leave the codec on "Unchanged" if quality matters.

What's the difference between .aac and .m4a if they're both AAC?

.aac is the raw ADTS bitstream — frames with a small sync header and nothing else. .m4a is the same AAC audio wrapped inside an MPEG-4 Part 14 container (the same container as .mp4, just audio-only), which adds atoms for metadata, cover art, chapter markers, and gapless playback hints. iTunes, Apple Music, the iPhone Files app, and most consumer players prefer .m4a. .aac shows up when AAC is the demuxed stream from a TS/MPEG transport, when streaming tools dump raw audio, or when a developer needs a container-free file. If you want tags and album art, see AAC to M4A.

Why is my cut slightly off from where I set it?

Because AAC is a block-based codec: each frame contains exactly 1024 PCM samples (or 960 in the LD/ELD profiles), which is about 23 ms at 44.1 kHz or 21 ms at 48 kHz. Lossless cuts have to land on a frame boundary — XConvert snaps your requested start and end to the nearest frame so the output stays in sync. If you need sample-accurate cuts, re-encode the AAC to PCM via AAC to WAV, trim, and re-encode — but that introduces a generation loss.

Can I cut HE-AAC or HE-AAC v2 files the same way?

Yes, but be aware that HE-AAC (also called AAC+ or aacPlus) layers Spectral Band Replication on top of AAC-LC, and HE-AAC v2 adds Parametric Stereo on top of that. The base frames are still 1024-sample AAC blocks, so frame-aligned cutting works the same. Some legacy players that only understand AAC-LC will play HE-AAC content as half-rate mono — that's a player limitation, not a cut artefact. The output profile matches the source unless you explicitly re-encode.

Will my cut AAC play on iPhone, iPad, and Apple Music?

iPhone, iPad, and macOS natively decode AAC, since Apple adopted AAC as the iTunes default in April 2003. A raw .aac file will play in the Files app and QuickTime, but it won't carry artwork or appear nicely in Music. If you want the clip to land in the Music library with metadata, wrap it as M4A via AAC to M4A before importing. For ringtones, you also need to rename to .m4r after wrapping (Apple's ringtone container is M4A under a different extension, capped at 30 seconds).

Can I cut AAC pulled out of a TS, MTS, or MP4 video?

Yes, once it's demuxed to a .aac file. AAC audio inside MPEG-2 transport streams (broadcast captures, Blu-ray rips) and MP4/MOV video usually demuxes cleanly to an ADTS .aac stream with FFmpeg's -c:a copy. Drop that file in and trim it like any other AAC. If you have the video file and want to extract+trim the audio in one step, use Audio Cutter, which accepts video inputs and outputs the audio-only segment.

How do I make the file smaller after cutting?

A cut already shortens the duration proportionally — a 60-second clip cut to 20 seconds is roughly one-third the size at the same bitrate. To shrink further: drop the bitrate (256 kbps → 128 kbps roughly halves the file with little audible loss for casual listening), switch to mono for voice (cuts size by ~40-50%), or use HE-AAC at 64 kbps for a near-broadcast quality stream at a quarter of AAC-LC 256. For aggressive reduction without re-cutting, see compress AAC.

Can I batch-cut multiple AAC files with the same start and duration?

Yes — drop in the whole set and apply one start/duration to every file. This is the usual workflow for stripping a uniform intro (say, the first 8 seconds) off every episode of a podcast feed or removing a station ID from a stack of broadcast captures. Files download individually or as a ZIP archive. If your sources have different intro lengths, process them in smaller batches with the appropriate offsets.

Should I convert to MP3 instead of cutting AAC directly?

Only if your playback target genuinely lacks AAC support. AAC is decoded natively by every modern browser, every iPhone since 2007, every Android since 1.0, CarPlay and Android Auto, every modern smart speaker, and the AAC profile is part of the Bluetooth A2DP spec. The honest case for MP3 is a pre-2005 hardware MP3 player, an older car stereo, or a podcast host that demands MP3 ingest. In that case, cut first to preserve quality, then see AAC to MP3 — converting once at the final length avoids encoding twice.