Trim 3G2 — Free Online Tool
Trim a 3G2 video or audio file to an exact start and end point, outputting a new 3G2 file optimized for CDMA mobile networks. The trim is performed using stream copy (no re-encoding), preserving the original libx264 video and AAC audio streams while keeping file sizes small for mobile delivery.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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Settings
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
This tool uses FFmpeg's stream copy mode (-c copy) to extract a segment of your 3G2 file without re-encoding any data. The 3G2 container, built on the MPEG-4 Part 12 base format for 3GPP2/CDMA networks, stores H.264 (libx264) video and AAC audio in a structure similar to MP4. Because the codec streams are copied byte-for-byte rather than decoded and re-encoded, the trim is fast and causes zero additional quality loss. The output retains the original bitrate and codec parameters, and the -movflags +faststart flag reorganizes the moov atom to the front of the file, which is critical for 3G2 files intended for progressive streaming over mobile networks.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary. In this browser tool, FFmpeg runs via WebAssembly (ffmpeg.wasm) entirely in your browser — no file data is sent to any server. |
-i input.3g2
|
Specifies the input file in 3G2 format. FFmpeg reads the 3GPP2 container and identifies the embedded H.264 video and AAC audio streams for processing. |
-ss 00:00:00
|
Sets the trim start time to the beginning of the file (0 seconds). Change this timestamp to seek to a later keyframe in the H.264 stream — for example, -ss 00:00:30 to start at 30 seconds. |
-to 00:00:10
|
Sets the trim end time to 10 seconds into the 3G2 file. Everything between -ss and -to is included in the output; everything outside that range is discarded without re-encoding. |
-c copy
|
Copies both the H.264 video stream and the AAC audio stream from the input 3G2 file byte-for-byte, skipping any decode/encode step. This makes the trim lossless in quality and extremely fast. |
output.3g2
|
Defines the output filename and container format. The .3g2 extension tells FFmpeg to wrap the copied streams in a new 3GPP2 container, complete with the -movflags +faststart optimization for mobile streaming playback. |
Common Use Cases
- Cut a long 3G2 video recorded on an older CDMA phone (e.g., Verizon or Sprint era devices) down to just the relevant clip before sharing.
- Extract a short segment from a 3G2 multimedia message (MMS video) to repurpose for a different mobile-compatible presentation.
- Remove silent or corrupted frames from the beginning or end of a 3G2 file received via a CDMA carrier before archiving.
- Trim a 3G2 ringtone or short video clip to fit within a carrier's MMS size limit without re-encoding and degrading quality.
- Isolate a specific scene from a 3G2 video captured by legacy mobile hardware for use in a video editing project that requires the original codec settings.
- Prepare a trimmed 3G2 clip for playback on an embedded mobile device or set-top box that only supports the 3GPP2 container format.
Frequently Asked Questions
No. The -c copy flag instructs FFmpeg to copy the H.264 video and AAC audio streams exactly as they are stored in the original 3G2 file, without decoding or re-encoding a single frame. The only caveat is that the trim point may not land exactly on a keyframe — FFmpeg will seek to the nearest keyframe at or before the specified start time, so the first fraction of a second may be silently adjusted.
3G2 files using H.264 video can only be cut cleanly at keyframes (I-frames). When you specify a start time with -ss, FFmpeg seeks to the nearest preceding keyframe to avoid creating a broken stream. If your source 3G2 has infrequent keyframes — common in low-bitrate mobile video — the actual cut point may differ by up to a second or two from your intended time. Re-encoding with a forced keyframe interval would allow frame-accurate cuts.
Yes. The output keeps the same libx264 video codec and AAC audio codec as the input, and the 3G2 container structure is preserved. The -movflags +faststart flag moves the moov atom to the front of the file, which improves compatibility with streaming players and mobile devices that begin playback before the full file is downloaded. The resulting file should play on any device that supported the original.
Modify the -ss and -to values in the command. The format is HH:MM:SS or HH:MM:SS.mmm for millisecond precision. For example, to trim from 30 seconds to 1 minute 15 seconds, use -ss 00:00:30 -to 00:01:15. Alternatively, replace -to with -t to specify a duration rather than an end timestamp — for example, -t 00:00:45 would trim 45 seconds starting from the -ss point.
The single command shown trims one file at a time, but you can wrap it in a shell loop for batch processing. On Linux or macOS, use: for f in *.3g2; do ffmpeg -i "$f" -ss 00:00:00 -to 00:00:10 -c copy "trimmed_$f"; done. On Windows Command Prompt, use a for loop: for %f in (*.3g2) do ffmpeg -i "%f" -ss 00:00:00 -to 00:00:10 -c copy "trimmed_%f". This is particularly useful for processing large batches of 3G2 clips from legacy CDMA devices.
Most metadata stored in the 3G2 moov atom — such as duration, creation time, and codec parameters — is automatically updated by FFmpeg to reflect the trimmed clip. The -movflags +faststart flag ensures the moov atom is placed at the beginning of the output file, which is essential for 3G2 files served over HTTP progressive download on mobile networks. However, any custom 3GPP2-specific metadata tags embedded in the original file may or may not be carried over depending on FFmpeg's container handling for that specific field.
Technical Notes
The 3G2 container is a close relative of MP4 (both derive from MPEG-4 Part 12/ISO Base Media File Format), but it includes 3GPP2-specific boxes tailored for CDMA network delivery, such as reduced overhead for low-bitrate transmission. When trimming 3G2 with -c copy, FFmpeg handles the container remux correctly, updating the sample tables (stts, ctts, stss) in the moov atom to reflect the new clip boundaries. The default codecs — libx264 for video and AAC for audio — are both supported natively in the 3G2 container per 3GPP2 C.S0050 specifications. One known limitation: because 3G2 does not support chapters or multiple audio tracks, no data of those types can be lost or mishandled during the trim. Subtitle streams are also unsupported, so any external subtitle file would need to be handled separately. For files over 1GB, the desktop FFmpeg command displayed on this page is recommended, as the WebAssembly environment imposes memory constraints for very large mobile video archives.