MyMediaTools

Convert 3GPP to MP4 — Free Online Tool

Convert 3GPP (.3gp) files to MP4 using H.264 video and AAC audio — the same codecs used in modern streaming platforms. This tool re-encodes your mobile-optimized 3G video into a universally compatible MP4 container with web-ready faststart metadata, making it playable on virtually any device, browser, or editing platform.

FFmpeg Command

Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg

Free — no uploads, no signups. Your files never leave your browser.

Estimated output:

Conversion Complete!

Download

How It Works

3GPP files use H.264 video and AAC audio internally, which are also the default codecs for MP4 — so at first glance this might seem like a simple container swap. However, because 3GPP files are optimized for constrained mobile environments (low bitrate, small resolution, limited header structure), this tool re-encodes both streams using FFmpeg's libx264 and AAC encoders at higher quality targets (CRF 23, 128k audio bitrate) to produce a cleaner, more compatible output. The -movflags +faststart flag also relocates the MP4 index (moov atom) to the beginning of the file, which is essential for web streaming and browser playback — a feature 3GPP files lack by design.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg binary — the open-source multimedia processing engine that handles all decoding, encoding, and container remuxing. In this browser-based tool, FFmpeg runs via WebAssembly (FFmpeg.wasm) without any server involvement.
-i input.3gp Specifies the input file as a 3GPP container (.3gp). FFmpeg will detect the internal codecs automatically — typically H.264 video and AAC or AMR audio — and select appropriate decoders before passing the streams to the encoders.
-c:v libx264 Re-encodes the video stream using the libx264 encoder, producing H.264 video at the default Main Profile rather than the constrained Baseline Profile common in 3GPP files. This ensures broad compatibility with browsers, smart TVs, and editing software.
-c:a aac Encodes the audio stream as AAC using FFmpeg's native AAC encoder. This transcodes whatever audio codec the 3GPP source contained — whether AAC or AMR — into a clean AAC track at the specified bitrate, which is the standard audio format for MP4 files.
-crf 23 Sets the Constant Rate Factor for the libx264 encoder to 23, which is the default quality level balancing file size and visual fidelity. For low-resolution 3GPP source material, CRF 23 is typically sufficient to preserve all visible detail without bloating the output file.
-b:a 128k Sets the audio bitrate to 128 kilobits per second for the AAC output track. This is a significant upgrade over the typical 3GPP audio bitrate of 32k–64k, resulting in noticeably cleaner and fuller sound in the MP4 output.
-movflags +faststart Moves the MP4 moov atom (the file's metadata index) from the end of the file to the beginning after encoding completes. Since 3GPP files always write this index last, this flag is essential to make the output MP4 suitable for web streaming and progressive playback in browsers.
output.mp4 Defines the output filename and, by extension, the container format. The .mp4 extension instructs FFmpeg to write an MPEG-4 Part 14 container, which supports the H.264 video and AAC audio streams produced by this conversion.

Common Use Cases

  • Uploading old video clips recorded on a 3G-era Nokia or early Android phone to YouTube, Instagram, or Vimeo, which reject or poorly handle 3GPP files
  • Importing mobile footage into video editing software like Adobe Premiere Pro or DaVinci Resolve, which may not natively support 3GPP containers
  • Archiving legacy mobile video from early-2000s feature phones into a future-proof MP4 format before the files become unreadable on modern systems
  • Preparing 3GPP video captured by IoT devices or dashcams for playback on smart TVs, media players like VLC, or Plex media servers
  • Converting MMS video attachments saved as .3gp files so they can be shared via messaging apps or email clients that require standard MP4 format
  • Increasing the audio bitrate from the typical 3GPP default (often 32k–64k) to a fuller 128k AAC for better sound quality before sharing a video publicly

Frequently Asked Questions

Not significantly — 3GPP files are typically recorded at very low resolutions and bitrates to suit 3G network constraints, and re-encoding cannot recover detail that was never captured. The conversion uses CRF 23, which preserves the existing visual quality without adding further compression artifacts. The most noticeable improvement is usually in audio, where the bitrate is raised from the typical 3GPP default of 32k–64k up to 128k AAC, producing noticeably cleaner sound.
3GPP files are heavily compressed for mobile network transmission, often using very low bitrates that sacrifice quality for small file size. When converting to MP4 with a standard CRF 23 setting and 128k audio, the encoder targets a higher quality level than the original 3GPP was encoded at, which results in a larger file. If file size is a concern, you can increase the CRF value (e.g., 28) or reduce the audio bitrate when running the FFmpeg command locally.
3GPP files do not support subtitle tracks or chapter markers, so there is nothing to carry over during this conversion. MP4, by contrast, fully supports both features. If you need to add subtitles or chapters to your output file, you would need to do so as a separate step after conversion using a tool like MKVToolNix or Handbrake.
Yes. AMR (Adaptive Multi-Rate) is a common audio codec in older 3GPP files recorded on feature phones, and while it's not listed as a default codec, FFmpeg can decode AMR and transcode it to AAC during this conversion. The output AAC audio at 128k will actually sound significantly better than the original AMR track, which typically operates at 4.75–12.2 kbps. If the tool encounters an AMR stream, FFmpeg handles the transcoding automatically.
The -movflags +faststart flag moves the MP4 file's metadata index (called the moov atom) from the end of the file to the beginning. 3GPP files store this index at the end by design, which is fine for downloaded playback but means a browser or streaming player must download the entire file before it can start playing. With +faststart applied to the MP4, playback can begin almost immediately, making it suitable for web embedding and online sharing.
For files over 1GB, copy the displayed FFmpeg command and run it locally on your desktop. To adjust video quality, change the -crf value: lower numbers like 18 produce higher quality at larger file sizes, while higher numbers like 28 produce smaller files with more compression. To adjust audio quality, change the -b:a value — options like 96k reduce file size, while 192k or 256k produce richer audio. For example: ffmpeg -i input.3gp -c:v libx264 -c:a aac -crf 18 -b:a 192k -movflags +faststart output.mp4

Technical Notes

3GPP (3GP) is a simplified derivative of the MPEG-4 Part 12 container, deliberately constrained to suit early mobile hardware and 3G bandwidth limits. It shares codec lineage with MP4 — both commonly carry H.264 video and AAC audio — but 3GPP imposes tighter restrictions on profiles, levels, and bitrates. This means that while a naive stream copy (-c copy) might appear to work, the resulting MP4 could fail on strict decoders due to 3GPP-specific H.264 profile constraints (often Baseline Profile, Level 1.3 or lower). Re-encoding with libx264 at the default Main Profile resolves these compatibility issues. Additionally, 3GPP files frequently carry only a single audio track at very low bitrates, contain no chapter data, and omit extended metadata fields that MP4 supports (like iTunes-style tags). This conversion does not fabricate missing metadata, so fields like title, artist, and description will not appear in the output unless they were present in the source. The -movflags +faststart post-processing step is particularly important here because 3GPP files always write the moov atom last, and without this flag the MP4 output would inherit that structure, breaking progressive web playback.

Related Tools

Convert 3GPP to MTS Convert 3GPP to MXF Convert 3GPP to M2TS Convert VOB to MP4 Convert MKV to MP4 Compress 3GPP Extract Audio 3GPP to MP3 Trim Video or Audio 3GPP