# 3GP subtitle generator: 110+ languages

Generate subtitles from your local 3GP soundtrack in 110+ languages. Check the audio and a free preview, then export SRT, VTT or ASS. Your video stays on your device.

## 3GP subtitle facts

Item | Result or policy

--- | ---

Tested audio | amr_nb

Detected container | mov,mp4,m4a,3gp,3g2,mj2

Subtitle targets | 110+ (118 currently listed)

Output | SRT / VTT / ASS

Video upload | No; only extracted audio is uploaded

Account duration limit | 8 hours; guest limit 3 hours

Full task price | USD $1/hour, rounded up to a cent

## Small mobile recordings can still need careful listening

3GP files are associated with mobile recording and sharing workflows, including older phones. A small file may contain a meaningful conversation even when the picture is low resolution. Subtitle generation primarily depends on the audio, so picture quality alone should not determine whether the recording is worth inspecting.

Choose a complete copy from your device or archive. Keep the original intact, especially if it is the only copy of a personal recording. SubLunio extracts a processing soundtrack locally and does not rewrite the source. You remain responsible for obtaining any participant permissions needed to process and use the recorded conversation.

## Narrowband speech has information limits

Some 3GP recordings use AMR narrowband audio. It can preserve understandable speech in a compact file, but it does not contain the same frequency detail as a modern high-quality microphone recording. Converting it to a larger or higher-rate file cannot recreate information that was never recorded.

The transcription MP3 uses a consistent 16 kHz mono format, while the actual source quality remains relevant. Listen for clipped syllables, wind noise and a distant speaker before judging a translation. When a name is unclear in the recording itself, automatic recognition should not be treated as reliable evidence of the intended spelling.

## Distinguish missing speech from a language-setting problem

Older mobile clips can be very short, contain long silence or capture only one side of a call. Inspect the duration and selected audio track. If the words are not present in that stream, choosing another target language will not produce a meaningful translation of them.

For a clip shorter than the preview window, the available preview is bounded by the recording’s actual remaining duration. Review the whole audible exchange when possible. A short, clear sentence and a noisy fragment can have very different outcomes even when their files use the same container and codec.

## Our 3GP fixture exercises AMR-NB conversion

The reproducible fixture pairs MPEG-4 video with 8 kHz AMR-NB audio inside a 3GP container. Two original test tones appear at defined positions, and Chromium and Firefox preserve those positions after decoding and MP3 conversion. The result verifies this narrowband audio path without claiming that upsampling improves the original recording.

Other mobile codec combinations need their own inspection. The synthetic fixture also says nothing about a real speaker’s accent or background noise. Use the preview to decide whether the available sound supports useful subtitles, and keep uncertain names or important statements on your list for manual review.

## Choose a language, then evaluate a preview

Select the file above, choose its speaking track and pick the language you want to read. SubLunio offers 110+ subtitle target languages. Source speech recognition has a separate supported list and defaults to Auto; setting the interface language does not limit your target choice. A brief listen can prevent a commentary or alternate dub from becoming the source of an otherwise well-timed translation.

The free web preview starts at the first subtitle and covers up to 5 continuous minutes. Compare the text with a clear line and a more difficult passage. You can start without an account, then sign in to retain the same valid task and continue with the audio already uploaded. A concise glossary can guide recurring names or specialist terms.

## Continue and save a portable subtitle

Full generation is priced at USD $1 per hour of the entire video, rounded up to a cent. The preview portion is included in that full duration. Use account credit or pay for the task; card payments have a $1.00 minimum and unused credit remains available. The price is based on duration rather than the original video file size.

Download SRT, VTT or ASS, choosing translated, original or bilingual text. Keep the subtitle beside the exact source edition and test dialogue at several points. The video stays local throughout extraction; server audio is temporary. Save your own subtitle copy and process only material you have the necessary rights to use. Automatic results still need review for names, meaning and timing.

Actual 3GP extraction check: amr_nb audio → MP3. Synthetic tones; this does not measure transcription quality.

[Media test report](https://sublunio.com/static/media-evidence/chromium-extraction.json)

## Does converting AMR-NB into a 16 kHz MP3 restore missing detail?

No. The conversion standardizes the processing format but cannot recreate information absent from the original narrowband recording.

## Can a tiny 3GP still contain useful dialogue?

Yes. File size and picture resolution do not alone determine whether the recorded speech is understandable.

## How much preview is available for a 3GP shorter than 5 minutes?

The preview is bounded by the actual remaining duration after the first subtitle.

## Which mobile speech codec is verified in the 3GP fixture?

The published test uses 8 kHz AMR-NB audio.

## Keep exploring

- [Compare supported video formats](https://sublunio.com/formats)

- [Choose an audio track](https://sublunio.com/guides/video-audio-tracks)

- [Process several files](https://sublunio.com/batch-subtitle-generator)

Source page: https://sublunio.com/3gp-subtitle-generator

Last updated: 2026-10-08