MyMediaTools

Convert MP4 to WMA — Free Online Tool

Convert MP4 video files to WMA audio using the wmav2 codec, extracting just the audio track from your video container into a Windows Media Audio file. This is ideal for creating WMA audio from video content while maintaining compatibility with Microsoft's media ecosystem, including Windows Media Player and legacy Windows devices.

FFmpeg Command

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Estimated output:

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How It Works

During this conversion, FFmpeg extracts only the audio stream from the MP4 container and discards the video, subtitle, and chapter data entirely — since WMA is a pure audio format and cannot carry any of these. The extracted audio, which may have originally been encoded as AAC or MP3 inside the MP4, is then re-encoded (transcoded) into the wmav2 codec — Microsoft's second-generation Windows Media Audio codec. This is a lossy-to-lossy transcode: even if the source audio was already compressed as AAC at 128k, it must be decoded back to raw PCM and then re-encoded as wmav2 at 128k, which introduces a small generation of additional compression artifacts. The resulting file uses the ASF (Advanced Systems Format) container, which WMA files are built upon, and is compatible with Windows Media Player, Xbox consoles, and a wide range of Windows-centric hardware and software.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg program, the open-source multimedia processing engine that powers this conversion both in the browser via WebAssembly and on your local desktop command line.
-i input.mp4 Specifies the input file — in this case an MP4 container that may contain video, audio, subtitles, and chapters. FFmpeg will read all available streams from this file and select the appropriate ones based on the output format.
-c:a wmav2 Sets the audio codec to wmav2, Microsoft's second-generation Windows Media Audio encoder. Since WMA is audio-only, all video and subtitle streams from the MP4 are automatically discarded, and the audio is re-encoded from its original format (typically AAC) into wmav2.
-b:a 128k Sets the audio bitrate to 128 kilobits per second for the wmav2 output stream. This is a balanced default that produces reasonable audio quality for music and speech while keeping file sizes moderate; increase to 192k or 256k for higher fidelity at the cost of larger files.
output.wma Specifies the output filename with the .wma extension, which tells FFmpeg to use the ASF container format with Windows Media Audio encoding. The .wma extension is the standard convention for audio-only ASF files and ensures compatibility with Windows Media Player and WMA-compatible devices.

Common Use Cases

  • Preparing audio content for distribution on platforms or devices that specifically require WMA format, such as older Windows Phone devices or legacy Zune media players
  • Extracting and converting the audio commentary track from an MP4 lecture or presentation video into a WMA file for playback in corporate Windows Media Player deployments
  • Converting MP4 podcast recordings or interviews to WMA for clients or listeners who use Windows-centric media software that preferentially handles WMA files
  • Creating WMA audio files from MP4 video content for use in Windows-based digital signage or kiosk systems that are configured to play Windows Media Audio
  • Archiving audio from MP4 home videos into WMA format to match an existing WMA-based music or audio library organized within Windows Media Player
  • Stripping audio from MP4 screen recordings or software demos into WMA format for use in Windows-compatible e-learning authoring tools that require WMA input

Frequently Asked Questions

Yes, some quality loss is unavoidable. The audio inside most MP4 files is already lossy-compressed (typically as AAC), so converting to WMA means decoding that AAC audio to raw PCM and then re-encoding it as wmav2 — a second round of lossy compression. This generational loss is generally subtle at 128k or higher bitrates, but audible differences may appear at 64k or 96k. If audio fidelity is critical, use the highest bitrate available (256k or 320k) to minimize the impact of the second encoding pass.
Basic metadata such as title, artist, album, and track number is typically carried over by FFmpeg during the conversion, since both the MP4 container and the ASF/WMA container support standard tag fields. However, MP4-specific metadata like chapter markers, embedded thumbnail artwork, and multiple audio track labels will be lost because the WMA format does not support those structures. You should verify the tags in Windows Media Player after conversion if metadata accuracy is important.
All of them are permanently dropped. WMA is a pure audio-only format built on the ASF container, which cannot store video streams, subtitle tracks, or chapter markers. FFmpeg automatically omits these streams when targeting a WMA output — only the first audio track from the MP4 is extracted and transcoded. If your MP4 has multiple audio tracks, only the default (first) one will be included in the WMA file.
wmav1 is Microsoft's original Windows Media Audio codec, while wmav2 is an improved second-generation version that generally offers better audio quality at the same bitrate through more efficient compression. This tool defaults to wmav2 because it is more widely supported across modern Windows software and hardware, and it delivers noticeably better results compared to wmav1 — especially in the 64k–128k bitrate range. There is no practical reason to choose wmav1 unless you are targeting a very specific legacy system that cannot handle wmav2.
Modify the value after the -b:a flag in the command. For example, to encode at 192k instead of the default 128k, change the command to: ffmpeg -i input.mp4 -c:a wmav2 -b:a 192k output.wma. The WMA format supports bitrates from 64k up to 320k — higher values produce larger files with better audio quality, while lower values produce smaller files with more compression artifacts. For music or high-fidelity audio, 192k or 256k is recommended; for voice or speech, 96k or 128k is usually sufficient.
Yes, on the command line you can use a simple loop to process multiple files. On Linux or macOS, run: for f in *.mp4; do ffmpeg -i "$f" -c:a wmav2 -b:a 128k "${f%.mp4}.wma"; done. On Windows Command Prompt, use: for %f in (*.mp4) do ffmpeg -i "%f" -c:a wmav2 -b:a 128k "%~nf.wma". This processes each MP4 in the current folder and outputs a matching WMA file. The browser-based tool on this page handles files one at a time, so the FFmpeg command is especially useful when you need to batch process a large collection.

Technical Notes

The WMA format is built on Microsoft's ASF (Advanced Systems Format) container, which is distinct from common open containers like MP4 or MKV. When FFmpeg writes a WMA file, it is technically producing an ASF container with a wmav2 audio stream — the .wma extension is simply the conventional name for audio-only ASF files. One important limitation is that WMA supports only a single audio track, so if your source MP4 contains multiple audio tracks (e.g., English and French dubs), only the first/default track will be encoded. WMA also lacks support for gapless playback metadata, which can matter for album-length music conversions. The wmav2 codec encodes in CBR (Constant Bitrate) mode by default when using -b:a, which is appropriate for streaming scenarios. DRM (Digital Rights Management) can technically be applied to WMA files through the ASF container, but FFmpeg does not add or replicate any DRM — the output file will be DRM-free regardless of the source. File size will typically be similar to the audio portion of the original MP4 at equivalent bitrates, since both AAC and wmav2 achieve comparable compression efficiency in the 128k–192k range.

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