Convert WMV to WTV — Free Online Tool
Convert WMV files to WTV format using H.264 video encoding and AAC audio, transforming Microsoft's legacy streaming format into Windows Media Center's broadcast recording container. This is especially useful for archiving WMV content alongside recorded TV metadata in a DVR-compatible format.
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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, typically storing video with the MPEG-4 Part 2-based msmpeg4 codec and audio with the WMA v2 (wmav2) codec. Since WTV does not support either of these codecs natively, this conversion requires a full re-encode of both streams. The video is decoded from msmpeg4 and re-encoded into H.264 (libx264) using a Constant Rate Factor of 23, which produces a visually balanced quality-to-filesize ratio. The audio is simultaneously decoded from wmav2 and transcoded into AAC at 128k bitrate, which is the WTV format's preferred audio codec for compatibility with Windows Media Center playback. The output is wrapped in the WTV container, which supports broadcast-style metadata embedding and multiple audio tracks — features the source WMV container did not leverage.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, which handles all decoding, re-encoding, and container packaging for this conversion. In the browser-based version of this tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm) without any server upload. |
-i input.wmv
|
Specifies the input WMV file, which is an ASF-container file carrying Microsoft's msmpeg4 video and typically wmav2 audio. FFmpeg reads and decodes both streams before re-encoding them for the WTV output. |
-c:v libx264
|
Sets the video encoder to libx264, re-encoding the video from WMV's msmpeg4 codec into H.264. This is required because the WTV container does not support the msmpeg4 codec used in WMV files. |
-c:a aac
|
Transcodes the audio from WMA v2 (wmav2), the default WMV audio codec, into AAC — the preferred audio codec for WTV files and the standard for Windows Media Center compatibility. |
-crf 23
|
Sets the Constant Rate Factor for H.264 encoding to 23, the default quality level. This is a perceptual quality target where lower values (e.g., 18) yield larger, higher-quality files and higher values (e.g., 28) produce smaller files with more compression artifacts. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second, providing a good balance of audio quality and file size for the WTV output. This is sufficient for most spoken-word and standard video content originally recorded in WMV. |
output.wtv
|
Specifies the output filename and triggers FFmpeg to use the WTV container format based on the .wtv file extension. FFmpeg wraps the H.264 video and AAC audio into the WTV structure used by Windows Vista and later Media Center editions for DVR recordings. |
Common Use Cases
- Archiving old WMV video recordings or home movies into Windows Media Center's WTV format so they appear alongside recorded TV content in a unified library
- Converting corporate training videos stored in WMV format into WTV so they can be managed and played back within a Windows Media Center DVR setup
- Migrating Windows Media Player content libraries into a WTV-based archive that supports richer metadata embedding for better catalog organization
- Re-packaging WMV broadcast clips or news segments into WTV format to leverage its DVR metadata fields for date, channel, and program tagging
- Converting WMV files received from older Windows-based capture cards into WTV, which is the native recording format for Windows Vista and later Media Center editions
- Testing H.264-encoded WTV output quality against an original WMV source to evaluate codec efficiency before committing to a large-scale archival conversion
Frequently Asked Questions
Yes, some quality loss is inevitable because both the video and audio must be fully re-encoded. The original WMV stores video using Microsoft's msmpeg4 codec, which must be decoded and then re-encoded into H.264 — a generational transcode that introduces compression artifacts. Using CRF 23 (the default) produces good visual quality for most content, but if you want higher fidelity, lower the CRF value to 18 or below in the FFmpeg command. The audio also undergoes lossy transcoding from WMA v2 to AAC.
The WTV container was designed around broadcast television recordings, and Windows Media Center uses H.264 and AAC as its primary codec pairing for compatibility with digital broadcast standards. Microsoft's msmpeg4 codec used in WMV files is not a supported video codec in the WTV container specification, so re-encoding to H.264 via libx264 is required. This also means the resulting WTV file is often more efficiently compressed than the original WMV, depending on source quality.
WMV files stored in the ASF container can carry some basic metadata, but they do not include broadcast-specific fields like channel name, program title, or air date. WTV supports these DVR metadata fields natively, but they cannot be populated automatically from a WMV source during conversion. You would need to add that metadata separately using a tool like MCEBuddy or by editing the WTV file's metadata fields manually after conversion.
WTV supports subtitle tracks, unlike the WMV/ASF format which does not. However, since the source WMV file cannot contain subtitles, there are no subtitle streams to carry over during this conversion. If you have a separate subtitle file (such as an SRT), you could incorporate it into the FFmpeg command by adding '-i subtitles.srt' and a subtitle codec flag, though WTV subtitle support through FFmpeg has limited compatibility and should be tested carefully.
Video quality is controlled by the '-crf' flag, which uses H.264's Constant Rate Factor scale. The default value of 23 is a good general-purpose setting. Lower values like 18 produce higher quality at larger file sizes, while higher values like 28 reduce file size with more visible compression. For archival purposes, a CRF of 18 is often recommended. To change it, replace '23' in the command with your desired value: for example, 'ffmpeg -i input.wmv -c:v libx264 -c:a aac -crf 18 -b:a 128k output.wtv'.
Yes, on Windows you can use a simple batch script to loop over all WMV files in a folder: 'for %f in (*.wmv) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "%~nf.wtv"'. On Linux or macOS, use: 'for f in *.wmv; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.wmv}.wtv"; done'. This is particularly useful for large collections exceeding 1GB where browser-based processing is impractical.
Technical Notes
The WMV format uses Microsoft's ASF container with the msmpeg4 video codec (an early, non-standard adaptation of MPEG-4 Part 2) and WMA v2 audio. Neither codec is compatible with the WTV container, making this a mandatory full transcode of both streams — not a remux. The libx264 encoder's CRF mode adapts bitrate dynamically to maintain consistent perceptual quality, which generally produces better results than the fixed bitrate mode used by WMV's msmpeg4 codec. One important limitation: WMV files with DRM (Digital Rights Management) protection cannot be converted by FFmpeg or any browser-based tool, as the content is encrypted. If your WMV source was produced by a screen capture tool or consumer camcorder using the older msmpeg4v2 variant, expect slightly different artifact patterns in the H.264 output due to the codec's non-standard quantization tables. The WTV container does not support chapter markers, so none will be present in the output regardless of source content. Multiple audio tracks from the source WMV can technically be preserved by adding '-map 0:a' flags, but most WMV files contain only a single audio stream. File sizes will vary significantly depending on source content complexity — static or low-motion WMV content will compress particularly well under H.264 CRF encoding.