Transcribe MP4 Audio to Text on iPhone
MP4 is the universal video container. Meeting recordings, phone clips, downloads, exports from every platform — if a video file exists, it's probably an MP4. The audio track inside it is often speech you need as text, and the gap between "the file is on my phone" and "the words are in my notes" is where transcription tools make their money.
iOS doesn't help: nothing built into the iPhone turns an imported video file into text. Web converters force you to upload the file to a third-party site, often pay per minute, and the file leaves your phone to get there. Desktop tools exist, but the file is on the phone, and the whole point of the workflow is to stay there.
Audio Notes AI imports MP4 directly. The app covers mp4, mov, m4v, avi, and mkv, extracts the audio track on-device, and transcribes server-side with Whisper. Two honest notes: uploads cap at about 50 MB, and compressed codecs are fine, because extraction outputs AAC M4A — a 2025 study on Whisper large-v3 found 128–192 kbps is the accuracy sweet spot, with higher bitrates adding nothing. To transcribe video to text on iPhone, the steps are below.
How to Transcribe MP4 to Text on iPhone
The flow is the file-first one from the video-to-text guide: get the file, import it, read the result.
1. Get the MP4 onto your iPhone
AirDrop it from a computer, download it from the platform that produced it, export your own clip from Photos, or save it from Safari — everything lands in Files, which is the staging area. A file that arrived as an email attachment saves to Files the same way; the source doesn't matter, only the destination. Your own recording is the easiest case: the app records in m4a, and any video you capture with the camera exports from Photos the same way. If you're still at the capture stage, our voice-to-text guide covers keeping the audio clean in the first place, because transcription quality tracks recording quality.
2. Import it, and the audio is extracted automatically
Choose the file in the Files picker inside Audio Notes AI, or use the iOS share sheet — the share extension accepts movie files from Files, Safari, and any app that shares. The app converts the audio track to M4A on your device with AVAssetExportSession — the same pipeline it uses for in-app recordings — then uploads only the audio for server-side transcription by openai/whisper-large-v3-turbo, with large-v3 as fallback. The server never sees the video frames. Transcription needs internet, runs on iPhone only, and rejects files over 90 minutes. The language picker has 100 entries — 99 Whisper languages plus Cantonese — if you'd rather set it explicitly; auto-detect is usually right, but a strongly accented file benefits from an explicit choice.
3. Translate, summarize, and export the transcript
The transcript stays in the source language and is searchable and copyable. When the detected language differs from your preferred language, it's automatically translated and summarized into your preferred language — no toggle, it's built in. Transcripts of MP4s live in the same notes library as every other recording, so search spans your whole archive, not just today's file, and the text stays editable — correct a name once and the note is fixed. Export a PDF, or share an encrypted link (AES-256-GCM, key in the URL hash, 24-hour expiry) with whoever needs the notes. Video exports from other platforms import identically: webinar and YouTube files are both MP4 at heart, and Apple's own MOV format rides the same pipeline. For files near the upload limit, exporting the audio alone from a video editor before importing keeps everything well inside the caps.
| Method | What you get | Limits | Best for |
|---|---|---|---|
| QuickTime / Photos | Playback of the MP4 | No transcription at all; the text never appears | Watching the video |
| Web converters | Upload-and-wait transcript | File leaves your phone; per-minute pricing — AI transcription runs about $0.10–0.50/min and human $1–3/min as of 2026 | One-off files on a desktop browser |
| Desktop transcription tools | Transcript on a Mac or PC | Not on iPhone; the file must travel to the computer first | Computer-centric workflows |
| Audio Notes AI | Whisper transcript, summary, translation, PDF export, encrypted share links | iOS only; 50 MB upload cap; 90-minute per-recording cap; no speaker attribution | Files already on the phone |
| Manual typing | Your own notes | Slow, error-prone, effectively impossible for long files | Two-minute clips |
FAQ
What video formats can I import?
mp4, mov, m4v, avi, and mkv — one extension list covers them all, and every one gets the same on-device audio extraction and server-side Whisper transcription. Audio-only files import directly too: m4a, mp3, wav, caf, aac, aiff, and mp4a. Apple's own MOV format is documented separately in our MOV transcription guide.
How does the audio get extracted?
On your device, before anything is uploaded. The app reads the video's audio track with AVAssetExportSession and saves it as an M4A, then uploads only the audio for server-side transcription. Extraction is local, transcription is cloud — the server never sees the video frames, which also keeps uploads small: compressed audio for a 90-minute file runs about 10–15 MB.
Is there a file size limit?
Uploads cap at 50 MB, and recordings at 90 minutes each. In practice the duration limit binds first: compressed audio for a 90-minute file is well under 50 MB. Bitrate research on Whisper large-v3 shows 128–192 kbps is the accuracy sweet spot anyway, so a heavily compressed MP4 loses nothing in accuracy while a 320 kbps master gains nothing.
Can I transcribe an MP4 in another language?
Yes. Whisper auto-detects the language from 99 supported languages plus Cantonese — 60+ at solid quality — and the transcript stays in the source language. When it differs from your preferred language, translation and summary happen automatically, which makes foreign-language videos readable without a second tool. The full pipeline is covered in our any-language guide, and chat voice notes follow the voice-message workflow.
Is it free?
The free tier is 60 minutes of lifetime transcription — a one-time allowance, not a monthly one. Pro is $5.99/month for 10,000 minutes per month, with the 90-minute per-recording cap. That covers a serious MP4 backlog — a course library, an archive of old meetings — without counting minutes.
Audio Notes AI imports video files — mp4, mov, m4v, avi, and mkv — extracts the audio, and transcribes it server-side with Whisper (large-v3-turbo, large-v3 fallback) in 60+ languages. Every account includes 60 minutes of lifetime transcription for free; Pro ($5.99/month) unlocks 10,000 minutes per month with a 90-minute cap per recording. Transcripts are translated and summarized automatically into your preferred language, and shared notes are encrypted with AES-256 on your iPhone before upload.
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Download Audio Notes AI free on the App Store — 60 minutes of lifetime transcription included.
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