MyMediaTools

Convert MOV to 3G2 — Free Online Tool

Convert MOV files to 3G2 format, re-encoding video with H.264 and audio with AAC to produce a compact, mobile-compatible container built for CDMA networks. This is a full transcode — not a remux — since 3G2's mobile-focused constraints require stripping out MOV-specific features like multiple audio tracks, chapter markers, and transparency.

FFmpeg Command

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

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Estimated output:

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How It Works

MOV is a flexible Apple container that can carry a wide range of codecs and rich metadata, including chapter markers, multiple audio tracks, and even transparency channels. 3G2, by contrast, is a tightly constrained mobile container developed for the 3GPP2 CDMA standard, supporting only H.264 or MJPEG for video and AAC or MP3 for audio. Because many MOV files already use H.264 video and AAC audio (the same codecs 3G2 accepts), it might seem like a simple remux — but a true remux is not possible here because the container structures differ significantly and 3G2 enforces mobile-specific bitrate and stream restrictions. The conversion therefore re-encodes both the video stream using libx264 at CRF 23 and the audio at 128k AAC, discarding any secondary audio tracks, subtitles, chapter data, and transparency layers that 3G2 cannot carry. The -movflags +faststart flag reorganizes the MP4-family metadata so the file can begin playing before it has fully downloaded, which is critical for mobile streaming over slower CDMA connections.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg binary. In this browser tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm) — no data leaves your machine.
-i input.mov Specifies the input QuickTime MOV file. FFmpeg reads the container and demuxes its video, audio, and any metadata streams for processing.
-c:v libx264 Re-encodes the video stream using the H.264 encoder (libx264), one of only two video codecs the 3G2 container supports. This is required regardless of what codec the source MOV used.
-c:a aac Re-encodes the audio stream to AAC, the default and most compatible audio codec for 3G2. Only the first audio track from the MOV is carried over, since 3G2 does not support multiple audio streams.
-crf 23 Sets the Constant Rate Factor for H.264 encoding to 23, a balanced default that delivers good visual quality at moderate file sizes suitable for mobile delivery. Lower values increase quality and file size; higher values (e.g., 28–35) reduce both for bandwidth-constrained CDMA streaming.
-b:a 128k Sets the AAC audio bitrate to 128 kilobits per second, a standard mobile audio quality level that balances clarity and file size. For voice-only content, 64k or 96k can be used to reduce the output size further.
-movflags +faststart Moves the MOOV atom (the file's index metadata) to the beginning of the 3G2 file. This is critical for mobile streaming over CDMA networks, as it allows the video to begin playing before the entire file has downloaded.
output.3g2 Specifies the output filename with the .3g2 extension, which tells FFmpeg to write a 3GPP2-compliant container. The file is written locally to your device — nothing is uploaded to a server.

Common Use Cases

  • Distributing a short promotional video to users on older CDMA feature phones or early smartphones that only support 3GPP2 playback
  • Archiving camcorder or iPhone MOV footage in a format compatible with legacy mobile multimedia messaging (MMS) systems that require 3G2 attachments
  • Preparing video content for CDMA carrier video portals or mobile broadcast platforms that mandate 3G2 container compliance
  • Reducing file size of a MOV clip for transmission over low-bandwidth CDMA data connections where MOV's overhead is impractical
  • Testing mobile video playback compatibility by converting a high-fidelity MOV master to the constrained 3G2 profile before publishing to a mobile content distribution network
  • Stripping complex MOV metadata — multiple audio tracks, chapters, transparency — down to a single clean video+audio stream for simple mobile delivery

Frequently Asked Questions

No — 3G2 does not support multiple audio tracks, chapter markers, or subtitle streams, so all of these are dropped during conversion. Only the first (default) audio track is carried into the output 3G2 file. If preserving chapters or alternate language tracks matters for your project, 3G2 is not the right target format; consider MP4 or MKV instead.
Yes, but the FFmpeg command handles it automatically by re-encoding to H.264 (libx264), which is one of only two video codecs 3G2 supports. ProRes and HEVC are not valid inside a 3G2 container, so a full video re-encode is mandatory regardless of the source codec. Expect longer processing times for large or high-resolution ProRes MOV files.
MOV can carry video with an alpha channel — for example, clips encoded with Apple ProRes 4444 used in compositing workflows. The 3G2 container and its supported codecs (H.264 and MJPEG) do not support transparency, so the alpha channel is permanently discarded during this conversion. The output will have a solid background, typically black, where transparent areas existed.
In most cases the 3G2 file will be noticeably smaller than the source MOV, especially if the MOV used a high-bitrate codec like ProRes or uncompressed video. The conversion targets CRF 23 with H.264 and 128k AAC — both are efficient lossy settings tuned for mobile delivery. However, if your MOV was already a compressed H.264 file at a similar or lower bitrate, the re-encode may produce a file of comparable size with a slight quality reduction due to generation loss.
Increase the CRF value in the command — for example, change -crf 23 to -crf 28 or -crf 35. Higher CRF numbers mean lower bitrate and smaller files at the cost of visual quality. For mobile CDMA streaming where bandwidth is very limited, values between 28 and 35 are common. You can also lower the audio bitrate from -b:a 128k to -b:a 96k or -b:a 64k to save additional space, which is often acceptable for voice-heavy content.
Yes — on the command line you can loop over files using a shell one-liner. On Linux or macOS: `for f in *.mov; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "${f%.mov}.3g2"; done`. On Windows Command Prompt: `for %f in (*.mov) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "%~nf.3g2"`. This browser tool processes one file at a time, but the displayed command is ideal for desktop batch jobs, especially for MOV files over 1GB.

Technical Notes

3G2 is structurally related to MP4 and MOV — all three descend from the MPEG-4 Part 12 ISO base media file format — but 3G2 enforces a much narrower codec profile designed for CDMA mobile constraints. The libx264 encoder used here targets the H.264 Baseline or Main profile by default, which maximizes compatibility with older CDMA handsets that may not support High profile features. The -movflags +faststart flag moves the MOOV atom to the beginning of the file, enabling progressive download playback over slow mobile connections — essential for the 3G2 use case. One important quality consideration: if the source MOV already contains H.264 video and AAC audio (as iPhone-recorded MOV files typically do), this conversion is still a full re-encode rather than a stream copy, introducing a generation of quality loss. There is no way to avoid this because the container rewrite requires re-muxing through 3G2's constrained structure. For archival purposes, always keep the original MOV. Additionally, 3G2 has no support for HDR metadata, color space signaling beyond basic Rec.601/Rec.709, or variable frame rate streams — all of which are silently normalized or dropped during conversion.

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