Convert 3G2 to FLAC — Free Online Tool
Extract and convert the audio track from a 3G2 mobile video file into a FLAC lossless audio file. Since 3G2 files typically contain AAC audio encoded at low bitrates for CDMA network transmission, this tool decodes that compressed audio and re-encodes it into FLAC — preserving every detail that survived the original AAC encoding without introducing any further quality loss.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your 3G2 file here
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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
3G2 files store audio using AAC (Advanced Audio Codec) compressed at low bitrates, optimized for transmission over 3GPP2/CDMA mobile networks — not for audio fidelity. During this conversion, FFmpeg demuxes the 3G2 container, discards the video stream entirely, and decodes the AAC audio to raw PCM. That raw audio is then re-encoded using the FLAC codec, which compresses it losslessly. The output FLAC file is bit-for-bit identical in audio content to what AAC produced — meaning no additional quality is lost beyond what AAC already discarded. FLAC then adds its own lossless compression layer, so the file is smaller than uncompressed PCM but perfectly reconstructible. The video track is automatically dropped because FLAC is a pure audio container.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool. In this browser-based tool, the same command runs via FFmpeg.wasm compiled to WebAssembly, so the behavior is identical to running it on your local desktop. |
-i input.3g2
|
Specifies the input file — a 3G2 container holding video (typically H.264) and audio (typically AAC-LC) encoded for CDMA mobile network delivery. FFmpeg reads both streams but will only use the audio for this conversion. |
-c:a flac
|
Sets the audio codec to FLAC (Free Lossless Audio Codec). This decodes the AAC audio from the 3G2 file to raw PCM and re-encodes it losslessly using FLAC, ensuring no additional quality degradation beyond what the original AAC encoding already introduced. |
-compression_level 5
|
Sets FLAC's compression level to 5, which is the default. This controls only encoding speed and file size — not audio quality, which is always lossless. At level 5, the output strikes a balance between compact file size and reasonable encoding time, suitable for the short-duration audio typically found in 3G2 mobile clips. |
output.flac
|
Defines the output file as a FLAC audio file. The .flac extension tells FFmpeg to use the FLAC muxer. The video stream from the 3G2 input is automatically omitted because the FLAC container is audio-only. |
Common Use Cases
- Archiving audio from old 3G2 video clips recorded on early CDMA phones (e.g., Verizon or Sprint-era devices) in a lossless format for long-term preservation
- Extracting a phone recording or voicemail saved as a 3G2 file into FLAC for use in audio editing software like Audacity or Adobe Audition without any additional encoding degradation
- Converting 3G2 audio recordings of interviews, lectures, or field notes into FLAC so they can be stored in a lossless archive alongside higher-quality recordings
- Pulling the audio from a 3G2 multimedia message (MMS attachment) into a format compatible with music players and audio libraries that support FLAC but not 3G2
- Preparing a 3G2 audio track for waveform analysis or forensic audio work, where FLAC's lossless nature ensures the analysis reflects the original AAC decode with no further artifacts
- Migrating a collection of legacy 3G2 mobile video files to audio-only FLAC as part of a digital media cleanup, reducing storage footprint while preserving maximum audio fidelity
Frequently Asked Questions
No — FLAC is lossless, but it cannot recover audio detail that AAC already discarded during the original 3G2 encoding. What FLAC guarantees is that no additional quality loss occurs during this conversion. The output FLAC file is a perfect lossless copy of the decoded AAC audio, so if your 3G2 file sounds thin or compressed, the FLAC will sound exactly the same way — just without any further degradation.
3G2 files use AAC audio compressed at very low bitrates (often 64–128 kbps) specifically to minimize file size for mobile transmission over CDMA networks. FLAC compression is lossless, which means it retains all audio data that AAC decoded — this results in a significantly larger file than the lossy AAC source. Additionally, the video stream is stripped out, but FLAC's audio data alone is inherently larger than a tightly compressed AAC stream. This is expected behavior and not a sign of an error.
FLAC supports rich metadata through Vorbis comment tags, but 3G2 files store metadata in a different format (MPEG-4 atoms). FFmpeg will attempt to map compatible metadata fields such as title, artist, and date during the conversion, but 3G2 files — especially those generated by mobile phones — rarely contain meaningful metadata beyond basic container information. You should verify and manually add tags in the output FLAC file using a tag editor if accurate metadata is important to you.
The -compression_level flag in FLAC controls the trade-off between encoding speed and output file size — it has no effect on audio quality, which remains lossless at every level. Level 5 is the default and offers a good balance: reasonable encoding speed with solid compression. Setting it to 8 produces the smallest possible FLAC file but takes significantly longer to encode, while level 0 encodes almost instantly with minimal compression. For most 3G2 source files, which are short mobile clips, the default level 5 is ideal.
The displayed command processes a single file, but you can batch convert using a shell loop. On Linux or macOS, run: for f in *.3g2; do ffmpeg -i "$f" -c:a flac -compression_level 5 "${f%.3g2}.flac"; done. On Windows Command Prompt: for %f in (*.3g2) do ffmpeg -i "%f" -c:a flac -compression_level 5 "%~nf.flac". This is especially useful when migrating a large archive of legacy mobile video files to FLAC.
The video stream is automatically discarded. Since FLAC is a pure audio container, it cannot store video data, so FFmpeg extracts only the audio track from the 3G2 file. No explicit flag is needed to drop the video — FFmpeg detects that the output format supports only audio and maps accordingly. If you need to keep the video, you would need to convert to a different output format such as MKV or MP4 instead.
Technical Notes
3G2 (3GPP2) is a variant of the MPEG-4 Part 12 container, closely related to MP4 and MOV, but specifically tailored for CDMA-based mobile devices from carriers like Verizon and Sprint. Its audio streams are almost universally AAC-LC at low bitrates — commonly 64 kbps or lower — because bandwidth conservation over CDMA networks was the primary design goal. When decoding AAC for re-encoding to FLAC, FFmpeg uses its native AAC decoder, which produces accurate PCM output. FLAC then compresses this PCM losslessly using its linear prediction algorithm. One important limitation: because the 3G2 source audio was already lossy, the FLAC output is technically 'lossless AAC decode' rather than a true high-fidelity lossless recording. The FLAC container supports replay gain, cue sheets, and seektable chunks — features that 3G2 does not offer — so the output file will be more compatible with audiophile software and archival workflows. Chapters and subtitle streams, which 3G2 and FLAC both omit, are not a concern for this conversion pair. There are no special container flags required for FLAC output, unlike MP4 or 3G2 which need -movflags +faststart for streaming optimization.