AAC to Text
Raw ADTS streams, broadcast archives, ripped audio
Raw .aac files often come from broadcast streams, radio captures, and extracted media tracks. Drop the file and Mictoo inspects its structure before transcribing the spoken audio with Whisper large-v3.
Drop your file here
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MP3 · MP4 · WAV · M4A · OGG · WEBM · FLAC · Max 25MB · Max 30 min
How it works
- 1
Drop your file
Upload from your device or drag and drop. Any common audio or video format.
- 2
Whisper transcribes the audio
Whisper large-v3 runs on our backend with automatic punctuation and per-segment timestamps.
- 3
Edit, export, share
Review the transcript, summarize with AI, translate to 50+ languages, and export as TXT, DOCX, PDF, or SRT.
Cleaner per-line layout with timestamps. Best for reading.
Why Mictoo for AAC transcription
Raw ADTS handled natively
Most raw .aac files are ADTS-framed (Audio Data Transport Stream). We detect the sync word 0xFFF and hand the stream to Whisper.
ADIF and LATM also supported
Less common ADIF (Audio Data Interchange Format) and LATM framings also work. No manual repackaging or ffmpeg step needed.
No container required
AAC usually lives inside M4A or MP4, but sometimes the raw stream lands on your disk. Mictoo accepts either without asking.
AI summary for archive segments
Broadcast segment, radio archive clip, or streaming dump. The AI summary lets you triage archives faster.
When AAC to text is the right fit
Broadcast radio archive
Segment recorded off HLS or Icecast stream that ships as raw AAC. Transcript makes the archive searchable.
HLS livestream capture
YouTube Live, Twitch, or radio HLS stream captured as an .aac chunk sequence. Drop the file, get the text.
Ripped iPhone audio
Audio extracted from an iPhone recording or shared file that lost its M4A container and came out as raw AAC.
Streaming service export
Podcast platform or streaming app that provides raw AAC downloads. Skip the conversion and drop the file directly.
Broadcast interview
Radio-hosted interview archived as raw AAC. Transcript is the citation-ready copy for articles or shows.
FFmpeg intermediate output
You extracted the audio track with ffmpeg -c:a copy and got a .aac. Drop it here instead of re-muxing to M4A first.
Raw AAC compared with M4A
AAC is an audio codec. A file ending in .aac is often a raw framed stream, while M4A usually wraps AAC audio in an MP4 container with seeking and metadata.
ADTS is common
Raw AAC is commonly stored as ADTS frames, especially when audio has been extracted from a stream or broadcast workflow.
M4A adds a container
M4A can carry the same AAC codec with timing, indexing, and metadata supplied by an MP4-based container.
Extension is only a clue
The file structure is inspected during processing, so a misleading extension does not become transcript text.
Broadcast workflows
Raw AAC often appears after HLS capture or audio extraction. Keep the original source reference for archival context.
Frequently asked questions
What kind of AAC files does Mictoo accept?
Raw AAC in ADTS framing (most common), ADIF, and LATM framings. We detect the sync word server-side and hand the stream to Whisper. AAC inside M4A (see the M4A page) also works but is a different intake path.
What is the difference between .aac and .m4a?
.aac is typically a raw ADTS bitstream: AAC frames with tiny 7-byte headers, no container. .m4a is AAC audio wrapped in an MP4 container with metadata and seek indexing. Both use the AAC codec, but the file structure differs.
My AAC file is over 60 MB. What now?
AAC at typical broadcast bitrates (128 kbps) is around 1 MB per minute, so 60 MB is roughly a one-hour recording. If you are signed in, we auto-split up to about 3 hours. Otherwise, downsample: ffmpeg -i in.aac -b:a 64k -ac 1 out.aac.
Does raw AAC produce worse transcripts than M4A?
No. The audio stream is identical; only the container differs. Whisper resamples to 16 kHz mono internally either way. Accuracy depends on the underlying recording quality, not on whether it is ADTS-framed or MP4-wrapped.
Does Mictoo transcribe non-English AAC?
Yes. Whisper large-v3 supports 50+ languages with auto-detection. For unusual accents or short broadcast clips, set the language explicitly for cleaner first-pass results.
Can I get SRT captions for the broadcast clip?
Yes. Download SRT or VTT after transcription. Timestamps align to the original AAC stream timeline for use in video editors, accessibility overlays, or archival indexing.
Is my AAC file kept on your servers?
No. The audio streams to the transcription provider, gets processed once, and is dropped from memory. We never write it to disk. Transcripts are only stored if you sign in and save to history.
Can I translate the transcript to another language?
Yes. After transcription, pick a target language and click Translate. Translation runs on GPT-4o-mini and appears alongside the original.
What if the file has a .aac extension but is actually M4A?
We inspect the magic bytes, not the extension. If the file starts with ftyp (M4A/MP4 signature), we treat it as M4A. If it starts with ADTS sync bytes, we treat it as raw AAC. Either way, transcription works.
How long does an AAC transcription take?
A 10-minute AAC typically finishes in 15-30 seconds end to end. Larger files near the upload cap take 45-80 seconds. Upload speed is often the longer step.