M4A to SRT Converter
Convert M4A audio files to accurate SRT subtitles. iPhone recordings, GarageBand exports, Mac audio — transcribed locally in your browser.
Drop your audio or video file here
MP3, WAV, M4A, MP4, MOV, WebM · Any size
Click any word to correct it
M4A is Apple's default audio format — but many subtitle tools don't support it natively.
iPhone voice memos, GarageBand recordings, and Mac audio exports all use M4A. Many online tools require conversion to MP3 first. AudioSRT accepts M4A directly and transcribes it locally — no conversion, no upload, no extra steps.
Who is this for?
- iPhone users transcribing voice memos and recordings
- Mac users converting audio captured in QuickTime or Voice Memos
- GarageBand creators exporting podcast episodes as M4A
- Apple ecosystem creators and content producers
From M4A file to finished SRT in minutes.
Upload M4A
Drop your M4A file directly. No MP3 conversion needed.
AI Transcribes Locally
Whisper AI runs in your browser. Your recording never leaves your device.
Edit Subtitles
Fix text, split lines, and adjust timing in AudioSRT's editor.
Export SRT
Download your SRT, VTT, or Premiere Pro JSON.
Native M4A support — no conversion required.
iPhone Voice Memos
Voice memos from iPhone export as M4A. Drop them directly into AudioSRT — no conversion step.
GarageBand Exports
GarageBand podcast and audio projects export as M4A. AudioSRT accepts them natively.
No Upload
M4A files transcribed in the browser. Your Apple recordings stay on your device.
SRT, VTT & More
Export SRT, WebVTT, plain text, or Premiere Pro JSON from any M4A transcription.
Why AudioSRT
Convert M4A to MP3 first
Drop M4A directly, no conversion
Upload iPhone recordings to cloud
Transcribe locally, stay private
Tools that reject Apple formats
Native M4A and AAC support
Complete guide: Converting M4A audio to SRT subtitles
M4A (MPEG-4 Audio) is Apple's default audio format — used by iPhone Voice Memos, GarageBand, QuickTime Player, and the Mac's native audio export tools. AudioSRT converts M4A files to SRT directly, without requiring any intermediate conversion step.
What is M4A?
M4A is an audio-only MPEG-4 container, typically encoding audio with AAC (Advanced Audio Coding). AAC is the successor to MP3 — it achieves better audio quality at the same bitrate, or equivalent quality at lower bitrate. Apple adopted AAC as its default codec for iTunes in 2003, and it has been the standard format for Apple audio ever since.
M4A files and MP3 files are often equivalent in practice for transcription purposes — both are lossy compressed audio. The main differences are the container format (MP4 vs MPEG) and codec (AAC vs MP3). AudioSRT supports both natively; no conversion is needed.
iPhone Voice Memo to SRT workflow
iPhone Voice Memos app records and saves audio as M4A. To convert an iPhone voice memo to SRT:
- Export from iPhone. Open Voice Memos, tap the recording, tap the three-dot menu, and select Share. AirDrop it to your Mac, or share to Files and transfer via USB.
- Drop into AudioSRT. Drag the .m4a file into AudioSRT. Transcription begins immediately in your browser.
- Edit the transcript. Fix any errors, especially proper nouns, names, and technical terms that Whisper AI may have mis-transcribed.
- Export SRT. Download your subtitle file in whatever format you need.
Voice Memos records at 44.1kHz AAC, typically at 128kbps or higher depending on your iOS settings. This is sufficient quality for accurate transcription of clear speech.
GarageBand podcast to SRT workflow
GarageBand is widely used for podcast production on Mac and iPad. After editing your podcast episode in GarageBand, export as M4A:
- In GarageBand (Mac): File → Share → Export Song to Disk. Choose AAC (M4A) format, Quality: High.
- In GarageBand (iPad): Tap the wrench icon → Song → Share Song → M4A.
- Drop the exported M4A into AudioSRT. For long podcast episodes (45–90 minutes), transcription may take a few minutes depending on your device.
- Export your episode transcript. Use plain text export for show notes, SRT for video versions, or VTT for web players.
M4A vs MP3: which is better for transcription?
At equivalent bitrates, M4A (AAC) audio is slightly better quality than MP3. A 128kbps M4A file will sound clearer and have fewer compression artifacts than a 128kbps MP3. For transcription, this means slightly better accuracy at low bitrates. In practice, for recordings at 128kbps or higher, the difference is small enough that it rarely matters.
If you have both M4A and MP3 versions of the same content, use whichever is higher bitrate. If they're the same bitrate, the M4A will give marginally better results. Either way, don't re-encode from one format to the other — that always degrades quality.
Mac QuickTime recordings
QuickTime Player on Mac can record audio from your microphone and saves as M4A. These files work identically to iPhone voice memos in AudioSRT. For screen recordings with audio, QuickTime saves as MOV — use AudioSRT's video upload to handle those.
Tips for recording better M4A on iPhone
The accuracy of M4A transcription is heavily influenced by recording quality. For iPhone recordings:
- Use the top microphone for voice memos. iPhone has multiple microphones; the top mic is optimized for close speech recording.
- Record in a quiet environment. iPhone mics are sensitive — they pick up fan noise, traffic, and room echo. These all reduce transcription accuracy.
- Hold the iPhone steady. Handling noise (taps, shuffles) introduces audio artifacts that confuse Whisper AI.
- Speak clearly at normal pace. Very fast speech reduces accuracy. Whisper AI performs best at a natural conversational pace.
Frequently asked questions
Can I convert iPhone voice memos directly?
Yes. Export the voice memo from the iPhone Voice Memos app via Share → AirDrop or Files. The exported .m4a file can be dropped directly into AudioSRT — no conversion to MP3 is needed.
Does AudioSRT support M4A from GarageBand?
Yes. GarageBand exports M4A (AAC) files on both Mac and iPad. Drop the exported file directly into AudioSRT.
Do I need to convert M4A to MP3 before transcribing?
No. AudioSRT accepts M4A files natively. Converting to MP3 first would degrade quality — don't do it.
What is the difference between M4A and AAC?
AAC is the audio codec; M4A is the file container. An M4A file contains AAC-encoded audio. They're often used interchangeably — renaming .m4a to .aac (or vice versa) is safe on most systems.
Can I convert M4A files purchased from iTunes?
iTunes purchases are DRM-protected M4P files, not standard M4A. DRM-protected files cannot be transcribed by AudioSRT or any other tool. Files you recorded yourself or downloaded from non-DRM sources work normally.
Is there a file size limit for M4A?
No. AudioSRT processes files locally with no size limit. Long podcast episodes and extended recordings work the same as short clips.
Can I transcribe M4A from a Mac screen recording?
QuickTime screen recordings save as MOV, not M4A. Use AudioSRT's video upload to process MOV files from QuickTime screen recordings.