Convert WMV to 3GP — Free Online Tool
Convert WMV files to 3GP format, re-encoding Microsoft's ASF-based video into a mobile-optimized container using H.264 (libx264) video and AAC audio — ideal for making Windows Media content playable on 3G-era and budget mobile devices with minimal file size.
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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 container with MPEG-4 Part 2 video (msmpeg4 or msmpeg4v2) and WMA audio (wmav2). Neither of these codecs is compatible with the 3GP container, so this conversion requires full re-encoding of both streams. The video is decoded from Microsoft's MPEG-4 variant and re-encoded using H.264 (libx264), which offers significantly better compression efficiency. The WMA audio is decoded and re-encoded to AAC, the standard audio codec for 3GP. The CRF-based quality control (CRF 23 by default) lets libx264 allocate bits dynamically, and a scale filter ensures frame dimensions are even numbers — a hard requirement for H.264 encoding that prevents common encoding failures with odd-resolution WMV source files.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — the open-source multimedia processing engine that powers this conversion. In the browser, this runs as FFmpeg.wasm compiled to WebAssembly. |
-i input.wmv
|
Specifies the input file in WMV format. FFmpeg reads the ASF container and identifies the Microsoft MPEG-4 video stream and WMA audio stream inside it for decoding. |
-c:v libx264
|
Sets the video encoder to libx264, the leading H.264 encoder. Since WMV's msmpeg4 codec is incompatible with 3GP, the video must be fully re-encoded, and H.264 is the standard high-efficiency choice for 3GP video. |
-c:a aac
|
Sets the audio encoder to AAC (Advanced Audio Coding), which is the standard audio codec for 3GP. The WMV's WMA (wmav2) audio is fully decoded and re-encoded to AAC since WMA is not supported in any 3GP player. |
-crf 23
|
Sets the Constant Rate Factor for H.264 encoding to 23, the libx264 default. This controls video quality vs. file size — the encoder allocates more bits to complex scenes and fewer to simple ones, balancing quality and keeping 3GP file sizes small enough for mobile use. |
-b:a 64k
|
Sets the AAC audio output bitrate to 64 kilobits per second, reflecting 3GP's mobile-first design where low bandwidth and compact file size are priorities. This is appropriate for speech-heavy content from WMV sources such as presentations or conferences. |
-vf scale=trunc(iw/2)*2:trunc(ih/2)*2
|
Applies a video filter that rounds the output frame dimensions down to the nearest even pixel count. This is required because H.264 (libx264) cannot encode odd-dimension video, and WMV files from older Windows tools sometimes have non-standard resolutions that would otherwise cause FFmpeg to fail with a 'width or height not divisible by 2' error. |
output.3gp
|
Specifies the output filename with the .3gp extension. FFmpeg uses this extension to select the 3GP/MP4-variant muxer, which packages the H.264 video and AAC audio into a 3GPP-compliant container optimized for mobile playback. |
Common Use Cases
- Making Windows Media Player video content from early 2000s archives playable on older Nokia, Samsung, or LG 3G handsets that never supported WMV or WMA
- Reducing the file size of WMV corporate training videos for distribution over slow mobile data connections or via MMS messaging
- Converting WMV recordings captured by older Windows-based screen recorders or webcam software into a format compatible with basic Android or Symbian media players
- Preparing WMV video content for upload to legacy mobile portals or WAP-based media services that only accept 3GP
- Archiving DRM-free WMV home videos into a smaller, widely-readable mobile format when storage on a feature phone or SD card is limited
- Converting WMV lecture recordings from Windows Media Encoder sessions into 3GP for students accessing course content on low-end mobile devices in low-bandwidth environments
Frequently Asked Questions
Yes, some quality loss is unavoidable because both the WMV source and 3GP output are lossy formats, and the conversion requires full re-encoding of both video and audio. The WMV's msmpeg4 video must be decoded and re-encoded to H.264, and the WMA audio must be decoded and re-encoded to AAC. However, H.264 at CRF 23 is generally quite efficient and the output quality is usually acceptable for mobile viewing. The bigger quality factor is the 3GP format's inherently low target audio bitrate of 64k, which may sound noticeably thinner than the original WMA audio track.
The scale filter 'scale=trunc(iw/2)*2:trunc(ih/2)*2' ensures both the width and height of the output video are divisible by 2. H.264 encoding with libx264 requires even dimensions, and WMV files sometimes have odd-pixel resolutions (especially those encoded by older Windows Movie Maker or Media Encoder tools). Without this filter, FFmpeg would throw an error and refuse to encode. The formula truncates each dimension to the nearest even number, so a 319x239 WMV becomes 318x238 — a negligible crop.
No. WMV files with Microsoft DRM (Digital Rights Management) encryption cannot be decoded or converted by FFmpeg or any standard conversion tool. The tool can only process DRM-free WMV files. DRM-protected WMV content is locked to authorized Windows Media Player instances and the encrypted stream cannot be decoded without the original license key. If you receive an error or get a blank output, DRM protection is a likely cause.
FFmpeg will by default select the first (or best-ranked) audio stream from the WMV file and encode only that to AAC in the 3GP output. Any additional audio tracks, such as alternate language dubs sometimes embedded in WMV files with multiple audio streams, will be silently dropped. If you need a specific non-default audio track, you would need to add '-map 0:a:1' (or the relevant stream index) to the FFmpeg command before the output filename to select it explicitly.
Video quality is controlled by the CRF value set with '-crf 23'. CRF stands for Constant Rate Factor — lower values produce higher quality and larger files, while higher values produce smaller files with more compression artifacts. For mobile 3GP content where file size matters, try '-crf 28' or '-crf 30'. For better quality closer to the WMV source, try '-crf 18'. Audio bitrate is set with '-b:a 64k'; reducing it to '-b:a 32k' or '-b:a 48k' will shrink the file further, though speech intelligibility may suffer below 48k.
Yes. On Linux or macOS, you can run a shell loop: 'for f in *.wmv; 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%.wmv}.3gp"; done'. On Windows Command Prompt, use: 'for %f in (*.wmv) 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 particularly useful for the desktop FFmpeg command since the browser tool processes one file at a time.
Technical Notes
WMV's ASF container uses Microsoft-proprietary codec identifiers (msmpeg4, msmpeg4v2) that are entirely incompatible with the 3GP container specification, which was designed by 3GPP for mobile multimedia delivery and mandates H.263, MPEG-4 Part 2, or H.264 for video and AMR or AAC for audio. This means there is no possibility of stream copying (remuxing) any part of a WMV file into 3GP — both video and audio streams require full decode-and-reencode cycles, making this a computationally intensive conversion. The default audio bitrate of 64k AAC in the output is intentionally conservative, reflecting 3GP's original design goal of minimizing bandwidth and storage on 3G handsets; the original WMV's WMA audio at 128k will sound noticeably compressed at this rate, particularly for music. WMV metadata fields (title, author, copyright, description) stored in ASF header objects are not preserved in the 3GP output, as the metadata structures between ASF and 3GP/MP4 differ and FFmpeg does not automatically map them. WMV files encoded with Variable Bit Rate WMA audio ('wmav2 VBR') may cause minor audio sync issues in the re-encoded AAC stream; if this occurs, adding '-async 1' to the command can help. The 3GP format does not support subtitles or chapters, so any metadata of that kind embedded in the WMV source is discarded.