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Supports: 3G2, 3GP, 3GPP, ASF, AV1, AVCHD +31 more
AAC (Advanced Audio Coding) is the audio codec that powers YouTube, Apple Music, Spotify, and the iTunes Store. Standardized in ISO/IEC 13818-7 (MPEG-2 Part 7, 1997) and extended in ISO/IEC 14496-3 (MPEG-4 Part 3, 1999), it delivers audibly transparent stereo at ~128 kbps VBR — a bitrate where MP3 still shows artifacts. Extracting just the AAC track from a video is much smaller than keeping the whole file and lets the audio play natively on phones, car stereos, and smart speakers.
<audio> element supports AAC across Chrome, Firefox, Safari, and Edge, and AAC is the recommended codec for HLS streaming. Smaller files load faster and use less mobile data.| Property | AAC | MP3 | M4A |
|---|---|---|---|
| What it is | Audio codec | Codec + container (one file format) | Container holding AAC (or ALAC) |
| Standard | ISO/IEC 13818-7 (1997), 14496-3 (1999) | ISO/IEC 11172-3 (1993) | MPEG-4 Part 14 (.mp4 family) |
| Typical bitrate (transparent stereo) | ~128 kbps VBR | ~192-256 kbps | ~128 kbps VBR (uses AAC) |
| Compression efficiency | Higher — roughly 15–20% smaller than MP3 at equal quality | Baseline | Same as AAC (same codec) |
| Native on Apple devices | Yes | Yes | Yes (preferred) |
| Plays in older car stereos / USB sticks | Mostly yes (post-2005) | Universal (post-1998) | Often no — many reject .m4a |
| Chapter markers / cover art | Limited (raw .aac is just frames) | Limited (ID3) | Full (MP4 atoms) |
| Used by | YouTube, Spotify, iTunes, HLS | Legacy music libraries, podcasts | iTunes, Apple Music, audiobooks |
| Use case | Bitrate | Notes |
|---|---|---|
| Voice / podcast (mono) | 64 kbps | Speech remains clear; halves file vs stereo |
| Voice / podcast (stereo) | 96 kbps | Good for interviews with ambient sound |
| Music (transparent) | 128 kbps VBR | Wikipedia / MPEG cite this as transparent for stereo |
| Music (audiophile) | 192-256 kbps | iTunes Store ships at 256 kbps AAC |
| Archival / mastering | 320 kbps or higher | Diminishing returns above 256; consider lossless instead |
If the source already uses AAC (most MP4s do), pick a bitrate at or above the source's bitrate to avoid a second lossy pass. Our default of 128 kbps is transparent for typical stereo material, but if you know the source is 256 kbps AAC, choose 256 kbps so you're effectively re-wrapping rather than re-encoding to a lower quality.
The codec inside the file is identical — AAC frames. The difference is the wrapper. A .aac file is a raw ADTS stream (just AAC frames with sync headers); a .m4a file is an MP4 container that holds the same AAC plus metadata atoms for title, artist, album art, and chapter markers. Apple devices prefer .m4a; older Android car stereos sometimes prefer .aac. If you want M4A specifically, use Convert Video to M4A.
Yes. Open the Trim group, set a start time and a duration. For example, start 00:01:30 and duration 60 to extract a 1-minute clip starting 90 seconds into the video. This runs as part of the conversion — you don't need a separate trim step.
Three usual culprits: (1) you picked a high bitrate like 256 or 320 kbps without realizing, (2) the source is multi-channel (5.1 surround) and AAC is preserving all channels — switch Audio Channel to stereo or mono to shrink it, or (3) the duration is longer than you remember. As a sanity check: 128 kbps stereo = ~1 MB per minute.
Quality Preset (Very High / High / Medium) uses VBR internally and is the most efficient — bits are spent on complex passages and saved on silence. Constant Bitrate is more predictable for streaming and easier to reason about ("256 kbps for 60 minutes = 115 MB"). For local playback, pick a Quality Preset; for HLS streaming or strict size budgets, pick Constant Bitrate.
AAC plays everywhere modern. Android has supported AAC playback since 1.0 (2008), Windows since Windows 7, and major Linux distributions ship FFmpeg-based players that decode AAC. The "Apple-only" reputation comes from .m4a files (which sometimes confuse non-Apple software) — the codec itself is universal. Chrome, Firefox, Safari, and Edge all support AAC in HTML5 audio.
Yes. The tool accepts 30+ video formats including MP4, MOV, MKV, AVI, WebM, FLV, MTS, M2TS, AVCHD, WMV, VOB, 3GP, MPEG, OGV, and more. The audio track gets re-encoded to AAC regardless of the input container.
If your target device or workflow is Apple-centric, AAC is better — same perceived quality at roughly 15–20% smaller size. If you need maximum compatibility with old car stereos, USB sticks, and 2000s-era devices, MP3 wins on universal support. For modern phones, web players, and streaming, AAC is the right choice. See Convert Video to MP3 for the MP3 path.
Our tool always runs the audio through an encoder pass, which is the right behavior when you're changing bitrate, channels, or sample rate. If you want a bit-perfect copy of the original AAC track and the source already uses AAC, FFmpeg's -c:a copy flag is the way to do that locally. For everything else (different bitrate, trim, channel change), re-encoding is required.