How do I extract the audio from my MP4 file as AAC?
+
Upload the MP4 file and the converter demuxes the audio stream, then transcodes it to AAC. There is no second video pass — the visual track is discarded immediately so extraction is much faster than a full re-encode.
What audio bitrate does the extracted AAC use?
+
Default bitrate for lossy AAC is 192 kbps, which is transparent for music. You can override to 320 kbps (audiophile) or 96-128 kbps (voice / podcast / smaller file). The bitrate dropdown is exposed in the advanced options before you click convert.
Will I lose audio quality going from MP4 to AAC?
+
If AAC is lossless (WAV, FLAC), every sample is preserved exactly. If AAC is lossy (MP3, AAC, OGG, Opus), the AAC codec recompresses the source audio — at 192 kbps the result is transparent for almost all content. Going lossy → lossless never recovers detail already discarded.
Does the AAC audio keep the original sample rate?
+
By default yes — 48 kHz audio in your MP4 stays 48 kHz in the AAC output. For CD-burning or legacy player compatibility you can downsample to 44.1 kHz via the sample-rate dropdown; the resampler is high-quality SoX-grade.
Can I extract audio from multiple MP4 files to AAC in one batch?
+
Yes — drop a folder of MP4 files and we extract audio in parallel. Premium users get more parallel workers; on a 50-file batch this is the difference between a couple of minutes and ten-plus minutes.
Will the AAC be tagged with title / artist / album metadata?
+
If the MP4 carries chapter or stream metadata, we copy title / artist / album fields into the AAC container. If not, the AAC comes out untagged — use a tag editor (Mp3tag, Picard) post-export for richer tagging.
How long does extracting AAC audio from a 1-hour MP4 take?
+
Audio demux + encode is fast — typically 5 to 15% of the source duration. A 1-hour MP4 → AAC finishes in roughly 3 to 9 minutes on the standard pipeline; Premium parallelism cuts this further for batch jobs.
Can I extract just a section of the MP4 audio as AAC?
+
Not in this tool directly — extract the full audio as AAC, then use /audio-trim/ or /audio-cutter/ to clip the section. The two-step path is usually faster than a combined operation and gives you precise waveform-level control.
Is my MP4 file private during the audio extraction?
+
Yes — same privacy model as every conversion: isolated workers, no human review, automatic deletion within minutes of completion. The detailed retention window is on /privacy/.
Why does the AAC file have silent gaps where the MP4 had sound?
+
Almost always a wrong-stream selection: MP4 had multiple audio tracks and the demuxer picked an empty or auxiliary stream. Use the advanced "audio stream" picker to select stream 0, 1, 2 explicitly, or target a AAC container that supports multi-track output (FLAC, OGG).
Can I keep AAC as stereo, mono, or 5.1 surround?
+
Channel layout is preserved from MP4 by default — a 5.1 MP4 produces a 5.1 AAC if the AAC codec supports it (AAC, FLAC, OGG, Opus). The downmix option forces stereo or mono — useful for podcast workflows where surround tracks waste bitrate.
Will the extracted AAC play on iPhone, car stereo, and Sonos?
+
MP3 plays everywhere with zero compatibility risk. AAC plays on Apple, most Android, and Sonos. OGG / Opus needs a recent player on iOS. The advanced device-preset dropdown picks the AAC codec most likely to play on your target hardware.