Convert MP4 to WTV — Free Online Tool
Convert MP4 video files to WTV (Windows Television) format for playback and archiving in Windows Media Center. This tool re-encodes your MP4 using H.264 video and AAC audio — the native codec pairing for WTV — making your recordings compatible with Windows Vista/7/8 Media Center DVR libraries.
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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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Settings
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
MP4 and WTV both support H.264 video and AAC audio, but they are structurally very different containers. MP4 is a general-purpose ISO-standard container with features like chapter markers, fast-start web streaming flags, and multiple subtitle tracks. WTV is a proprietary Microsoft broadcast recording wrapper designed to carry DVR metadata, broadcast scheduling information, and TV program data. Because FFmpeg cannot simply remux the streams without rewriting container-level structures, this conversion performs a full re-encode: the video is compressed with libx264 at CRF 23 and the audio is encoded to AAC at 128k bitrate. Chapter metadata from the MP4 will be dropped since WTV does not support chapters, but subtitle tracks and multiple audio tracks can be preserved. The resulting WTV file is structured in a way that Windows Media Center can index, browse, and play it as though it were a recorded broadcast.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program. In this browser tool, FFmpeg runs as a WebAssembly (wasm) binary entirely within your browser — no file is sent to a server. The same command works identically in a desktop FFmpeg installation for processing files larger than 1GB. |
-i input.mp4
|
Specifies the input file — your source MP4. FFmpeg reads the MP4 container and demuxes its video, audio, and any subtitle streams for processing into the WTV output. |
-c:v libx264
|
Sets the video encoder to libx264, which produces H.264-compressed video. H.264 is the default and most compatible video codec for WTV files in Windows Media Center, and it is natively supported by both the source MP4 and the target WTV container. |
-c:a aac
|
Sets the audio encoder to AAC (Advanced Audio Coding), the default audio codec for WTV. AAC is a good match for WTV's Media Center environment, offering better sound quality than MP3 at equivalent bitrates and broad compatibility with Windows Media Center playback. |
-crf 23
|
Sets the H.264 Constant Rate Factor to 23, which is FFmpeg's default quality level for libx264. In this MP4-to-WTV re-encode, CRF 23 produces a balanced trade-off between file size and visual quality; lower values (e.g., 18) yield higher quality at larger file sizes. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second. For typical recorded TV content — speech, music, and general broadcast audio — 128k AAC provides acceptable fidelity. Raise this to 192k or 256k in the command if your source MP4 has high-quality stereo or surround audio you want to preserve more faithfully. |
output.wtv
|
Specifies the output filename and, critically, the '.wtv' file extension, which tells FFmpeg to mux the encoded streams into the WTV container format. Windows Media Center identifies WTV files by this extension for library indexing and DVR integration. |
Common Use Cases
- Importing MP4 home videos or downloaded content into a Windows Media Center library so they appear alongside recorded TV shows with proper thumbnail browsing
- Archiving MP4 recordings of over-the-air broadcasts back into WTV format after editing out commercials in a third-party video editor
- Converting MP4 files from a dashcam or security camera for playback on a Windows Vista or Windows 7 Home Premium Media Center PC connected to a living-room TV
- Preparing MP4 video content for a legacy Windows Media Center HTPC (Home Theater PC) setup where the WTV format is the expected input for the DVR library
- Re-wrapping an MP4 produced by a screen recorder or capture card into WTV so it integrates with Windows Media Center's recorded TV management and metadata tools
- Converting MP4 episodes of digitized VHS tapes to WTV for storage in a Windows Media Center collection alongside other broadcast recordings
Frequently Asked Questions
WTV does support subtitle tracks, and FFmpeg can carry subtitle streams into the WTV container. However, the default command shown here does not explicitly map subtitle streams, so you may need to add '-map 0' to your FFmpeg command to include all streams, including subtitles. Chapter markers from your MP4 will be permanently lost, as WTV has no support for chapters.
WTV is a broadcast-oriented container format with a less compact structure than MP4, and it does not support the '-movflags +faststart' optimization that MP4 uses. Additionally, because this is a full re-encode rather than a remux, the encoding parameters (CRF 23 for video, 128k for audio) may result in a different bitrate than your original MP4 depending on how it was originally compressed. If your source MP4 was encoded at a very efficient bitrate, re-encoding can sometimes produce a larger output file.
Windows Media Center was removed from Windows 10 and is not available on Windows 11. WTV files can still be opened in Windows 10 using third-party players like VLC or MPC-HC, but native Media Center DVR library integration is only available on Windows Vista, 7, and 8. If you need broad modern compatibility, MP4 is likely a better long-term format choice.
Yes, this is a lossy re-encode. The video is re-compressed with H.264 at CRF 23 and the audio is re-encoded to AAC at 128k, regardless of the quality of the source MP4. If your original MP4 was encoded at a higher quality setting, some generation loss will occur. To minimize quality loss, you can lower the CRF value (closer to 0 means higher quality but larger files) in the FFmpeg command before running it locally.
To improve video quality, lower the '-crf' value in the command — for example, '-crf 18' produces noticeably higher quality than the default '-crf 23', at the cost of a larger file. To increase audio fidelity, raise the '-b:a' value to '192k' or '256k'. For example: 'ffmpeg -i input.mp4 -c:v libx264 -c:a aac -crf 18 -b:a 192k output.wtv'. These changes are especially practical when running the command locally on files larger than 1GB.
Yes. On Windows, you can use a for loop in Command Prompt: 'for %f in (*.mp4) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "%~nf.wtv"'. On macOS or Linux, use: 'for f in *.mp4; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.mp4}.wtv"; done'. The browser-based tool processes one file at a time, so the command-line approach is far more practical for batch jobs.
Technical Notes
WTV is a proprietary Microsoft container format introduced with Windows Vista Media Center, internally based on Microsoft's Advanced Systems Format (ASF) technology — the same family as WMV/WMA — extended to carry broadcast DVR metadata such as program guide data, channel information, and recording timestamps. Despite this ASF heritage, FFmpeg supports WTV encoding using standard codecs: libx264 for video and AAC or MP3 for audio. Notably, the MJPEG video codec is also supported in WTV for motion-JPEG workflows, though H.264 is the default and most practical choice. The WTV container does not support the ISO Base Media File Format features that make MP4 versatile for web use, such as fast-start atom reordering, chapter atoms, or TTML/WebVTT subtitle formats. Metadata embedding in WTV is supported at the broadcast-recording level (title, channel, description), but application-layer metadata like iTunes-style tags from your MP4 may not map cleanly. For files over 1GB — common with long recordings — the displayed FFmpeg command is especially valuable for running the conversion locally, as desktop FFmpeg has no file size ceiling and will outperform browser-based processing for large inputs.