Convert 3G2 to 3GP — Free Online Tool
Convert 3G2 files (the CDMA-era mobile format from 3GPP2) to 3GP (the GSM/WCDMA-standard mobile container) using H.264 video and AAC audio, optimized for low-bandwidth playback. Both formats share similar codec support, but 3GP's stricter mobile-streaming constraints make this conversion useful for cross-network device compatibility.
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FFmpeg Command
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Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
Despite their similar appearances, 3G2 and 3GP are distinct container specifications from competing mobile standards bodies. During this conversion, the video stream is re-encoded using the libx264 H.264 encoder (rather than simply remuxed) to ensure compliance with 3GP's mobile playback constraints, including the mandatory scale filter that forces frame dimensions to even numbers — a hard requirement for H.264 in mobile containers. The audio is encoded with AAC at 64k bitrate, reflecting 3GP's low-bandwidth design philosophy. The output is a leaner 3GP file tuned for devices and networks that expect the 3GPP standard rather than the 3GPP2 (CDMA) variant.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, the open-source multimedia framework that handles all decoding, encoding, and container remuxing in this conversion pipeline. |
-i input.3g2
|
Specifies the input file in the 3G2 container format — the CDMA-targeted mobile video format from the 3GPP2 standard that will be decoded and repackaged into 3GP. |
-c:v libx264
|
Re-encodes the video stream using the libx264 H.264 encoder, producing a video track that meets 3GP's mobile playback requirements and is broadly compatible with devices expecting the 3GPP standard. |
-c:a aac
|
Encodes the audio stream using AAC (Advanced Audio Codec), which is the standard audio codec for 3GP files and ensures compatibility with mobile players expecting this format. |
-crf 23
|
Sets the H.264 Constant Rate Factor to 23, the default quality level that balances file size and visual quality — appropriate for the small-screen, low-bandwidth context 3GP is designed for. |
-b:a 64k
|
Sets the AAC audio bitrate to 64 kilobits per second, matching 3GP's low-bandwidth audio convention and keeping the output file size small enough for MMS or constrained mobile storage. |
-vf scale=trunc(iw/2)*2:trunc(ih/2)*2
|
Applies a video filter that rounds the width and height down to the nearest even number — a mandatory step for H.264 encoding in the 3GP container, which cannot accommodate odd pixel dimensions. |
output.3gp
|
Specifies the output filename and the .3gp extension, which tells FFmpeg to write the result into the 3GP container format defined by the 3GPP mobile standard. |
Common Use Cases
- Making video clips recorded on an older CDMA phone (e.g., Verizon or Sprint devices from the 2000s–2010s) playable on GSM-based phones and feature phones that only recognize 3GP
- Preparing archival 3G2 footage for upload to legacy media platforms or embedded systems that explicitly require the 3GP container format
- Reducing file size of 3G2 clips for MMS messaging on networks with strict payload limits, since 3GP's lower default audio bitrate (64k vs 128k) produces smaller files
- Batch-converting a collection of 3G2 mobile videos for playback on older Android or Symbian devices whose media players support 3GP but not 3G2
- Standardizing a mixed library of CDMA and GSM phone recordings into a single 3GP format for consistent playback in a retro mobile media archive
- Enabling 3G2 videos shot on CDMA networks to be shared via platforms or apps targeting international GSM markets where 3GP is the expected format
Frequently Asked Questions
Yes, some quality loss is expected because this conversion re-encodes the video rather than copying it. Both 3G2 and 3GP are lossy formats, and re-encoding with libx264 at CRF 23 introduces a second generation of compression. However, since both formats are designed for small screens and low bandwidth, the practical difference at typical 3G2 source quality levels is usually minimal and often imperceptible on mobile-sized displays.
The scale filter `scale=trunc(iw/2)*2:trunc(ih/2)*2` ensures the output video dimensions are even numbers, which is a hard requirement for H.264 encoding in the 3GP container. If your source 3G2 file happens to have odd pixel dimensions (uncommon but possible on certain CDMA devices), omitting this filter will cause FFmpeg to throw an error and fail. It's safe to leave in for all conversions since it has no effect when dimensions are already even.
3G2 was developed by 3GPP2 for CDMA networks (used by carriers like Verizon and Sprint in the US), while 3GP was developed by 3GPP for GSM/WCDMA networks (used by most international carriers). They share many codec options including H.264 and AAC, but differ in container structure and the network ecosystems they target. Devices and platforms built around one standard may not reliably play files from the other, which is why explicit conversion is sometimes necessary.
Adjust the `-crf` value to control video quality. Lower CRF values produce better quality at larger file sizes — for example, `-crf 18` is near-visually lossless for mobile content, while `-crf 35` produces a much smaller file with noticeable quality reduction. For 3GP files intended for low-bandwidth streaming or MMS, values between 28–35 keep file sizes manageable. The default CRF of 23 is a balanced starting point for general use.
Yes — replace `-b:a 64k` in the command with a lower value like `-b:a 32k` or `-b:a 48k` to reduce audio file size further. The default 64k AAC bitrate is already quite conservative and appropriate for voice-heavy mobile video, but dropping to 32k can meaningfully reduce file size for MMS or constrained storage scenarios, with speech remaining intelligible. Increasing beyond 64k (e.g., `-b:a 96k`) will improve audio quality but produces a larger file that may be less suited for true 3GP mobile use cases.
Yes. On Linux or macOS you can run: `for f in *.3g2; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 64k -vf scale=trunc(iw/2)*2:trunc(ih/2)*2 "${f%.3g2}.3gp"; done`. On Windows Command Prompt, use: `for %f in (*.3g2) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 64k -vf scale=trunc(iw/2)*2:trunc(ih/2)*2 "%~nf.3gp"`. This is especially useful for converting a library of archived CDMA phone recordings in one pass.
Technical Notes
Both 3G2 and 3GP support H.264 (libx264) and AAC as their primary codecs, so the codec choice itself is not a significant compatibility hurdle. The key differences lie in the container metadata and the structural defaults each format imposes. Notably, 3G2 uses a default AAC audio bitrate of 128k in this tool's configuration while 3GP defaults to 64k — reflecting the more aggressive bandwidth constraints of the 3GPP specification. Neither format supports subtitles, chapters, or multiple audio tracks, so no metadata of those types will be present to lose. The `-movflags +faststart` flag used for 3G2 output is intentionally absent in the 3GP output command; instead, the scale filter takes precedence as the format-critical flag for 3GP. Because 3G2 source files from CDMA-era devices were often recorded at very low resolutions (e.g., 176×144 QCIF or 320×240), the re-encoding step does not upscale content — the output 3GP will match the source resolution, just repackaged and re-encoded within the 3GP container structure.