Convert WMV to 3G2 — Free Online Tool
Convert WMV files to 3G2 format, transcoding Microsoft's proprietary ASF-wrapped MPEG-4 video into a CDMA-optimized mobile container using H.264 and AAC. This is ideal for making legacy Windows Media content playable on older 3GPP2-compatible mobile devices and low-bandwidth networks.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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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
WMV files use Microsoft's proprietary ASF (Advanced Systems Format) container with video encoded in MS-MPEG4 variants (msmpeg4 or msmpeg4v2) and audio in WMA (wmav2). Neither of these codecs is compatible with the 3G2 container, so this conversion requires full re-encoding of both streams. The video is decoded from MS-MPEG4 and re-encoded to H.264 (libx264) using a CRF of 23, which targets a visually consistent quality level rather than a fixed bitrate — appropriate for the variable content typical in WMV files. The audio is decoded from WMA and re-encoded to AAC at 128k, the standard codec for 3G2. The output is wrapped in the 3GPP2 container with the +faststart flag, which repositions the MP4/3G2 moov atom to the beginning of the file for progressive streaming over CDMA networks. Expect a modest file size reduction in most cases, since H.264 is significantly more efficient than MS-MPEG4 at equivalent perceptual quality.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool. This is the same engine that powers the in-browser conversion via FFmpeg.wasm (WebAssembly), so the output of the browser tool and the desktop command will be functionally identical. |
-i input.wmv
|
Specifies the input WMV file. FFmpeg will detect the ASF container and identify the video stream (MS-MPEG4 variant) and audio stream (typically WMA/wmav2) automatically before decoding them for re-encoding. |
-c:v libx264
|
Sets the video encoder to libx264, which encodes the decoded MS-MPEG4 video frames from the WMV into H.264. H.264 is the standard video codec for the 3G2 container and delivers significantly better compression efficiency than the source MS-MPEG4 codec. |
-c:a aac
|
Sets the audio encoder to AAC, transcoding the WMA (wmav2) audio from the WMV source into AAC. AAC is the default and most compatible audio codec for the 3G2 container and is well-suited for the low-bitrate mobile streaming scenarios 3G2 was designed for. |
-crf 23
|
Sets the Constant Rate Factor for H.264 encoding to 23, the libx264 default. This produces a visually balanced quality level for typical WMV content — lower values (e.g., 18) increase quality and file size, while higher values (e.g., 28–35) reduce file size at the cost of more visible compression artifacts in the 3G2 output. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second. This is a standard quality level for mobile audio in 3G2 files, providing clear speech and music while keeping file sizes appropriate for CDMA network delivery. |
-movflags +faststart
|
Moves the 3G2 container's moov atom (metadata index) to the beginning of the output file after encoding completes. This enables progressive streaming over CDMA networks — the core use case for 3G2 — so playback can begin before the entire file is downloaded. |
output.3g2
|
Specifies the output filename and tells FFmpeg to use the 3G2 container format based on the file extension. The resulting file will be a 3GPP2-compliant container holding H.264 video and AAC audio, compatible with CDMA mobile devices and 3G2-aware players. |
Common Use Cases
- Making archived Windows Media Video content from the early 2000s accessible on legacy CDMA mobile devices that only support 3GPP2 playback
- Converting corporate training videos originally distributed as WMV files into a mobile-friendly 3G2 format for field staff using older handsets on CDMA networks
- Repurposing Windows Media Player-targeted content for distribution through CDMA carrier video portals that require the 3G2 container
- Reducing the effective bitrate of high-bitrate WMV recordings by leveraging H.264's superior compression efficiency in the 3G2 output for low-bandwidth delivery
- Batch-converting a library of WMV screen recordings or webinars into 3G2 for archiving in a mobile-compatible format with better codec longevity than MS-MPEG4
- Preparing WMV video content for devices and embedded systems in CDMA regions where 3G2 remains a supported playback format
Frequently Asked Questions
Yes — this is a lossy-to-lossy conversion, meaning both the input WMV (MS-MPEG4 video, WMA audio) and the output 3G2 (H.264 video, AAC audio) use lossy compression. Each decode-encode cycle introduces some generation loss. However, because H.264 (libx264) is a far more efficient codec than MS-MPEG4, the output at CRF 23 will often look comparable to or better than the original at equivalent or even smaller file sizes. You can lower the CRF value (e.g., to 18) in the FFmpeg command to reduce compression and preserve more quality at the cost of a larger file.
MS-MPEG4 (the codec used in WMV files) is an older, less efficient codec than H.264 used in the 3G2 output. H.264 achieves similar perceptual quality at roughly half the bitrate of MS-MPEG4 in many scenarios. Additionally, the ASF container used by WMV sometimes includes Windows Media DRM metadata, index chunks, and streaming overhead that the leaner 3G2 container does not carry. The combination of a more efficient video codec and a simpler container typically results in a smaller output file.
No — 3G2 does not support DRM, embedded subtitles, or multiple audio tracks. WMV files can carry Windows Media DRM, closed captions, and alternate audio streams via the ASF container, but none of these will survive the conversion to 3G2. Only the primary video and first audio track will be carried over. If your WMV file contains DRM protection, the conversion will fail unless the file is already unlocked and playable on your system.
CRF (Constant Rate Factor) controls the quality-to-file-size tradeoff for H.264 encoding. The default value of 23 is a balanced middle ground. Lower values (e.g., 18) produce higher quality and larger files, while higher values (e.g., 28–35) produce smaller files with more visible compression artifacts. For WMV sources that already show compression artifacts from MS-MPEG4 encoding, setting CRF lower than 23 won't recover lost detail — it just avoids adding further degradation. For high-motion WMV content like sports or gaming footage, a CRF of 18–20 is recommended.
Yes. On Linux or macOS, you can use a shell loop: `for f in *.wmv; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "${f%.wmv}.3g2"; done`. On Windows Command Prompt, use: `for %f in (*.wmv) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "%~nf.3g2"`. The browser-based tool processes one file at a time, so the FFmpeg command is particularly useful for bulk conversions of large libraries.
The +faststart flag causes FFmpeg to rewrite the 3G2 file after encoding so that the moov atom (the container's metadata and index block) is placed at the beginning of the file rather than the end. This is critical for streaming over CDMA networks, which is the primary use case for 3G2 — a player or network server can begin transmitting the video immediately without needing to download the entire file first. Without this flag, the file would still play locally but would not stream progressively.
Technical Notes
The WMV-to-3G2 conversion is a full transcode of both video and audio streams — there is no opportunity for stream copying (remuxing) because MS-MPEG4 is not a valid video codec in the 3G2/MP4 family of containers, and WMA audio is similarly incompatible. The ASF container used by WMV stores streams in a fundamentally different structure than the ISO Base Media File Format that underlies 3G2, so the entire file must be demuxed, decoded, re-encoded, and remuxed. One notable limitation of 3G2 relative to WMV is that it supports only a single audio track — if the source WMV contains multiple audio streams (e.g., multi-language tracks), only the default or first audio stream will be included. Chapter markers and embedded subtitle data present in the WMV will be silently dropped. The 3G2 format was designed for constrained CDMA network delivery, so very high bitrate WMV sources (e.g., 6000k–8000k) will be compressed significantly by the CRF-based H.264 encoder; the output quality will still be good, but the file is intended for mobile playback rather than broadcast archiving. For long-term archiving purposes, a format like MP4 or MKV with H.264 would be more appropriate than 3G2.