To convert an MP3 to text on Android, import the file into a transcription app. In Retexta: tap New task, open More templates, choose Transcript only, tap Import audio and pick the MP3. Retexta converts the file on your phone into a speech format, uploads it and returns the text. M4A and WAV files work the same way. If you want a summary, notes or an email instead of the raw transcript, pick that goal instead of Transcript only.
| File | What Retexta does with it (app code) |
|---|---|
| MP3 (.mp3) | Decoded with Android's built-in decoder, then transcribed |
| M4A (.m4a, AAC) | Decoded with Android's built-in decoder, then transcribed |
| WAV (.wav), 16-bit PCM | Converted by Retexta's own code, then transcribed |
| Other WAV (8-bit, 24-bit, float) | Handed to Android's decoder; 24-bit and float are not on Android's list, see below |
| Video files (.mp4 with video) | Not shown: the picker lists audio files only |
Convert an MP3 to text on Android, step by step
Retexta is a cloud voice to text and AI writing app for Android.
- Put the MP3 on your phone or in a cloud drive that shows up in Android's file picker (for example Google Drive).
- Open Retexta and tap New task.
- Under What do you want to do?, choose the result you want:
- Transcript only (under More templates): the plain transcript, no AI rewrite.
- Summarize a meeting: a summary with decisions and action items.
- Take notes (under More templates): structured notes, a task list or a short summary.
- Translate (under More templates): the content in another language.
- Under Add your input, tap Import audio. Android's file picker opens and shows audio files only.
- Select the MP3.
- Retexta converts the audio to 16 kHz mono on your phone, uploads it and transcribes it on its servers. Long files are split into parts of up to 5 minutes before upload, at pauses where the app finds them.
- Read the result. Retexta marks AI results with "AI-generated. Check important details."
Import audio is part of Retexta Pro, and so is every goal except Transcript only. Retexta is free to try: new users get a few free Pro results to view in the app. Copying, sharing, exporting and screenshots of results need Retexta Pro or credits, and so does everything after the free results, Transcript only included.
M4A to text
M4A is the usual format of many phone recorders and of audio saved from some messaging apps. It holds AAC audio in an MPEG-4 container, and Android lists AAC in .m4a among the formats its decoders support. In Retexta you import an M4A file exactly like an MP3: New task, a goal, Import audio, pick the file.
WAV file to text
WAV files are uncompressed and large, but they are the easiest case. When a WAV file holds 16-bit PCM audio (the most common kind), Retexta converts it with its own code: it mixes the channels to mono and resamples to 16 kHz, without Android's decoders. Other WAV variants go to Android's decoder. Android's list of supported formats names only 8-bit and 16-bit linear PCM for WAV, so a 24-bit or 32-bit float WAV from a studio recorder may fail. Export such files as 16-bit WAV or as MP3 first.
Which audio formats Retexta imports
Retexta accepts every file Android labels as audio and hands it to Android's own decoders (MediaExtractor and MediaCodec), except 16-bit PCM WAV, which it reads itself. What decodes therefore follows Android's list of supported media formats. We read the app code on September 25, 2026; we have not tested these formats on a phone.
| Format | Android decoder support (Android Developers) | Tested with Retexta on a device |
|---|---|---|
| MP3 (.mp3) | Yes | Not tested by us |
| AAC in M4A (.m4a), 3GP (.3gp), ADTS (.aac) | Yes | Not tested by us |
| WAV, 16-bit PCM | Read by Retexta's own code | Not tested by us |
| WAV, 8-bit PCM | Yes | Not tested by us |
| FLAC (.flac) | Android 3.1 and later | Not tested by us |
| Ogg Vorbis (.ogg) | Yes | Not tested by us |
| Opus in Ogg (.ogg) | Android 5.0 and later | Not tested by us |
| AMR (.amr, .3gp) | Yes | Not tested by us |
Retexta needs Android 7.0 or later, so all of the Android version notes above are met. Files ending in .opus usually hold Opus audio in an Ogg container, but Android's list names only the .ogg ending, so treat .opus files as untested.
When a file fails
If Retexta shows "Couldn't convert this audio file for transcription.", the phone could not decode the file. Convert it to MP3 or 16-bit WAV with an audio converter and import it again. If it shows "We couldn't pick up any speech in this recording.", the file is probably silent or very quiet.
What affects the result
- The recording, not the format. A clear MP3 transcribes better than a noisy WAV. Distance to the microphone, background noise and people talking over each other matter much more than the file type. Our guide on improving speech to text accuracy has practical tips.
- Stereo becomes mono. Retexta mixes all channels into one before transcription. If two speakers were recorded on separate channels, that separation is not kept.
- The language. Retexta detects the spoken language automatically; you do not pick it. Written results are available in 50+ languages.
- Speaker names and timestamps. Retexta's transcript is plain text without speaker labels or timestamps.
Free and online MP3 to text options
- Online converters ask you to upload the file to a website. Before you upload a private recording, check who runs the site and what it does with uploads.
- Your phone's recorder app may transcribe, but usually only recordings made in that app. See how to transcribe a voice memo on Android.
- Retexta is free to try with a few free Pro results. Importing files needs Retexta Pro.
What to do with the text next
Recorded an interview? Read how to transcribe an interview. Working with episodes? See how to transcribe a podcast. For voice notes from WhatsApp, read how to convert a WhatsApp voice message to text. More about the app: Retexta, voice to text for Android.
Sources
Checked by FLAME Apps on September 25, 2026.
- Android Developers, Supported media formats (last updated May 22, 2025): audio decoders and containers, WAV bit depths, Android versions.
- Retexta app code (Android, version 2026.1.23, minimum Android 7.0): import picker for
audio/*(RecordScreen.kt), conversion to 16 kHz mono (AudioNormalizer.kt), splitting into parts of up to 5 minutes (CloudAudioChunker.kt), automatic language detection and language list (TranscriptionLanguageCatalog.kt), error messages (app strings). - Retexta: plan names as shown in the app and on its Google Play listing.
