Convert AC3 to WMA — Free Online Tool
Convert AC3 (Dolby Digital) audio files to WMA format using the wmav2 codec, directly in your browser — no uploads required. This is useful for moving surround-sound or broadcast audio into Microsoft's ecosystem for use in Windows Media Player, older Windows devices, or DRM-enabled distribution workflows.
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FFmpeg Command
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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
AC3 is a lossy Dolby Digital codec commonly encoding 5.1 surround sound at bitrates up to 640kbps. WMA (Windows Media Audio) is a separate lossy codec developed by Microsoft, and there is no shared codec between these two formats — so this conversion is a full transcode, not a remux. FFmpeg decodes the AC3 audio stream to raw PCM, then re-encodes it using the wmav2 codec into a WMA container. Because WMA is inherently a stereo-oriented format and does not support discrete 5.1 channel output in the same way AC3 does, any multichannel audio in the source file will be downmixed to stereo during encoding. This is a generation loss scenario: decoding lossy AC3 and re-encoding to lossy WMA introduces cumulative quality degradation, so the output will not match the fidelity of the original AC3 source.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg executable, the open-source multimedia processing engine that handles all decoding and encoding in this conversion pipeline. |
-i input.ac3
|
Specifies the input file — in this case, an AC3 Dolby Digital audio file. FFmpeg will detect the AC3 codec automatically and decode it to raw PCM audio for re-encoding. |
-c:a wmav2
|
Sets the audio encoder to wmav2 (Windows Media Audio version 2), Microsoft's standard WMA codec. This is the default and preferred WMA codec for modern compatibility, producing better quality than the older wmav1 at equivalent bitrates. |
-b:a 128k
|
Sets the target audio bitrate for the WMA output to 128kbps. This is the standard default for stereo WMA audio; since the AC3 source is being downmixed from potentially multichannel to stereo, 128kbps provides reasonable quality for most listening use cases. |
output.wma
|
Specifies the output filename with the .wma extension, which tells FFmpeg to wrap the wmav2-encoded audio in the ASF (Advanced Systems Format) container — the standard container for WMA files used by Windows Media Player and compatible software. |
Common Use Cases
- Preparing Dolby Digital audio ripped from a DVD or broadcast recording for playback on legacy Windows devices or software that only supports WMA natively.
- Converting AC3 audio tracks from TV recordings into WMA for use in older Windows Media Center or Windows Media Player libraries.
- Reformatting AC3 broadcast audio content for distribution through platforms or DRM systems that require WMA as the delivery format.
- Downmixing a 5.1 Dolby Digital surround audio file to stereo WMA for use in a Windows-centric multimedia project or presentation.
- Archiving or sharing Dolby Digital audio in a format compatible with Microsoft Surface tablets or older Windows Phone devices that lacked AC3 decoder support.
- Batch converting a library of AC3 audio files extracted from video into WMA for ingestion into a Windows-based digital asset management system.
Frequently Asked Questions
Almost certainly yes. AC3 is designed to carry discrete 5.1 (and even 7.1) surround channels, which is one of its primary strengths in DVD and broadcast use. The wmav2 codec used for standard WMA output is a stereo codec, so FFmpeg will downmix your multichannel AC3 audio to two-channel stereo during transcoding. If preserving surround sound is critical, WMA is not the right target format — consider formats like AAC or keeping the AC3 source.
Yes, this conversion involves two stages of lossy compression, which is inherently a quality-degrading process. FFmpeg first decodes the AC3 audio to uncompressed PCM (no loss at that step), but then re-encodes it using the wmav2 codec at 128kbps by default. Since the original AC3 was already lossy, encoding the decoded output again as WMA compounds the artifacts. The audible impact depends on the source bitrate and content, but you will generally not achieve AC3-level fidelity in the WMA output.
The 128kbps default reflects WMA's typical use as a stereo streaming or playback codec rather than a high-fidelity archival format. Because the conversion also downmixes surround audio to stereo, a lower bitrate can be acceptable for stereo output. However, if your source AC3 was at 192kbps, 256kbps, or higher and you want the best possible WMA output quality, you should manually set the bitrate to 192kbps or 256kbps in the FFmpeg command using the -b:a flag.
You can adjust the output bitrate by modifying the -b:a flag in the command. For example, to encode at 192kbps instead of the default 128kbps, run: ffmpeg -i input.ac3 -c:a wmav2 -b:a 192k output.wma. Supported WMA bitrates include 64k, 96k, 128k, 160k, 192k, 256k, and 320k. Higher values will produce better audio fidelity at the cost of a larger file size. Note that increasing the bitrate beyond the quality ceiling of your source AC3 file will not recover any quality lost in the original encoding.
Yes, you can substitute -c:a wmav1 in the FFmpeg command if you need compatibility with very old Windows Media Player versions or legacy hardware that predates WMA version 2. In practice, wmav2 is the better choice for virtually all modern use cases — it produces superior audio quality at the same bitrate and is supported by all devices that support WMA at all. wmav1 is mainly relevant if you are targeting devices from the late 1990s or very early 2000s.
AC3 files typically carry very minimal metadata — they are a raw audio codec container without robust tagging support, unlike formats such as MP3 or FLAC. WMA, by contrast, supports rich metadata tags including title, artist, album, and genre. FFmpeg will attempt to copy any metadata present in the AC3 source to the WMA output, but since AC3 files rarely contain tags in practice, your WMA output will likely need metadata added separately after conversion using a tag editor.
Technical Notes
The wmav2 codec (Windows Media Audio version 2) used in this conversion is a Microsoft-proprietary lossy codec optimized for stereo audio at medium bitrates, making it well-suited for streaming and Windows ecosystem playback but a poor fit for high-fidelity multichannel audio. Because AC3 supports Dolby Digital's full surround encoding (typically 5.1 at 192–640kbps), and wmav2 does not natively carry discrete multichannel tracks in standard WMA containers, FFmpeg performs an automatic downmix using its default channel layout mapping when the source is multichannel. Users processing broadcast or DVD-sourced AC3 files should be aware that the spatial audio information encoded in those files — rear surrounds, LFE channel — will be folded into two channels and that spatial information is unrecoverable. WMA also natively supports DRM (Digital Rights Management) via the ASF container structure, but FFmpeg cannot apply Microsoft's DRM encryption, so outputs will be unprotected WMA. File sizes at the default 128kbps WMA setting will typically be smaller than a comparable AC3 file encoded at 192kbps or above, reflecting both the lower bitrate and the reduction from multichannel to stereo. For batch processing of multiple AC3 files on the command line, the FFmpeg wildcard pattern or a shell loop such as for f in *.ac3; do ffmpeg -i "$f" -c:a wmav2 -b:a 128k "${f%.ac3}.wma"; done is an efficient approach for files over 1GB that exceed browser-based processing.