Convert WTV to WebM — Free Online Tool
Convert WTV recordings from Windows Media Center into WebM files using VP9 video and Opus audio — two open, royalty-free codecs optimized for web playback and HTML5 streaming. This tool re-encodes your broadcast recordings entirely in your browser, with no server uploads, making your DVR content accessible on any modern web platform.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your WTV file here
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Free — no uploads, no signups. Your files never leave your browser.
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
WTV files typically contain H.264 or MPEG-2 video alongside AC-3 or AAC audio, wrapped in a Microsoft-proprietary container designed for Windows Media Center's DVR system. Because WebM uses VP9 video and Opus audio — neither of which is compatible with WTV's native codecs — this conversion requires a full re-encode of both streams. FFmpeg decodes the WTV video and re-encodes it using the libvpx-vp9 encoder with CRF-based quality control, while the audio is transcoded to Opus via libopus. The WTV container's broadcast metadata (channel info, program titles, timestamps) is largely dropped during this process, as WebM does not have equivalent metadata fields. The result is a self-contained WebM file natively playable in Chrome, Firefox, and Edge without any plugins.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — in this browser-based tool, this runs as a WebAssembly (FFmpeg.wasm) instance entirely within your browser, with no data sent to any server. |
-i input.wtv
|
Specifies the input file in WTV format — FFmpeg's WTV demuxer reads the Microsoft proprietary container and exposes the internal video, audio, and metadata streams for processing. |
-c:v libvpx-vp9
|
Re-encodes the video stream using the libvpx-vp9 encoder, which is required since WebM only supports VP9 (or VP8) video — the original WTV video codec (MPEG-2 or H.264) is not a valid WebM video codec. |
-c:a libopus
|
Transcodes the audio to Opus using the libopus encoder, replacing the WTV's original audio (typically AC-3 or AAC) with WebM's preferred open audio codec, which offers better quality-per-bitrate than both MP3 and AAC. |
-crf 33
|
Sets the VP9 encoder to constant quality mode with a CRF value of 33 — this is the primary quality control knob for the video output, where lower values yield higher quality. A value of 33 is suitable for web-delivery of broadcast TV content at moderate file sizes. |
-b:a 128k
|
Sets the Opus audio bitrate to 128 kilobits per second — appropriate for stereo broadcast audio, preserving dialogue and ambient sound quality from the original TV recording without unnecessary file size overhead. |
-b:v 0
|
Disables the VP9 video bitrate cap, which is required to activate pure CRF mode in libvpx-vp9. Without this flag, VP9 would treat the encoding as constrained quality rather than constant quality, potentially limiting visual fidelity on complex broadcast scenes. |
output.webm
|
Specifies the output filename with the .webm extension, signaling FFmpeg to use the WebM container — a Matroska-based format that encapsulates VP9 video and Opus audio in a structure natively supported by all major modern browsers. |
Common Use Cases
- Publishing a recorded TV segment to a website or blog using an HTML5 <video> element without requiring proprietary codec support
- Archiving Windows Media Center DVR recordings in an open, non-Microsoft-dependent format before decommissioning a Windows Vista/7/8 Media Center setup
- Sharing a recorded broadcast clip on a platform or CMS that accepts WebM uploads but not WTV files
- Reducing the file size of a lengthy TV recording for web delivery, taking advantage of VP9's superior compression compared to the original broadcast codec
- Preparing recorded sports, news, or documentary footage for embedding in a web-based video player that requires WebM/VP9 compatibility
- Converting a WTV recording for playback on a Linux or macOS system where Windows Media Center's proprietary format cannot be opened natively
Frequently Asked Questions
Yes, this is a lossy-to-lossy conversion — your WTV recording is already compressed broadcast video, and re-encoding it to VP9 introduces a second generation of compression. The default CRF value of 33 for libvpx-vp9 produces a reasonable quality-to-file-size balance for web delivery, but if you want to preserve as much of the original quality as possible, lower the CRF value (e.g., CRF 20 or lower). Keep in mind that no WebM output will exceed the quality of the original WTV source, regardless of settings.
The libvpx-vp9 encoder requires both flags to be set for pure CRF (constant quality) mode. Without '-b:v 0', VP9 defaults to constrained quality mode, where the CRF value acts as a target floor but a bitrate cap also applies. Setting '-b:v 0' removes that bitrate constraint, allowing the encoder to use as many bits as needed to hit the target quality at every frame. This is the recommended approach for archival or quality-focused encoding.
Generally no. WTV files store rich DVR metadata including program title, episode information, channel number, and broadcast timestamps in Microsoft-specific metadata fields. WebM (based on the Matroska container) supports a different set of metadata tags, and FFmpeg does not automatically map WTV broadcast metadata to WebM tags. You may find that basic fields like title are partially preserved, but channel, guide data, and recording timestamps will typically be lost in the output file.
By default, FFmpeg selects only the best audio stream (usually the first or highest-quality track) when converting to WebM. WebM does technically support multiple audio tracks, but the default command does not map all streams. To preserve multiple audio tracks, you would need to add '-map 0:v -map 0:a' flags to explicitly include all streams, and use the '-c:a:0 libopus -c:a:1 libopus' syntax to encode each track to Opus.
Change the '-crf 33' value to control quality — lower numbers produce higher quality and larger files, while higher numbers produce smaller files with more compression artifacts. For VP9, the scale runs from 0 (lossless-like) to 63 (very low quality); values between 20 and 35 are most practical for video content. For example, replacing '-crf 33' with '-crf 20' would produce noticeably sharper output at the cost of a larger file, which is worthwhile when archiving an irreplaceable broadcast recording.
The displayed command converts a single file, but you can adapt it for batch processing on Windows using a for loop: 'for %f in (*.wtv) do ffmpeg -i "%f" -c:v libvpx-vp9 -c:a libopus -crf 33 -b:a 128k -b:v 0 "%~nf.webm"'. On Linux or macOS, use: 'for f in *.wtv; do ffmpeg -i "$f" -c:v libvpx-vp9 -c:a libopus -crf 33 -b:a 128k -b:v 0 "${f%.wtv}.webm"; done'. This is especially useful for converting an entire Media Center library in one pass, since the browser-based tool handles files one at a time.
Technical Notes
WTV is a container format exclusive to Windows Vista/7/8/10 Media Center, and its internal codec depends on the broadcast source — recordings may contain MPEG-2 video (common for over-the-air DVB/ATSC) or H.264 video (common for cable and satellite), with audio in AC-3, AAC, or MPEG audio. FFmpeg's WTV demuxer handles all of these cases, but the re-encode to VP9 will take significantly longer than a simple remux due to VP9's computationally intensive compression algorithm — expect encoding times of 0.3–0.7x realtime in a browser environment. WebM's VP9 output offers excellent compression efficiency, often producing files 30–50% smaller than the original WTV at comparable visual quality. One important limitation: WTV's subtitle/caption streams (typically CEA-608/708 or DVB subtitles) may not survive the conversion, as WebM only supports WebVTT subtitles and FFmpeg does not automatically transcode broadcast captions to that format. If subtitle preservation is critical, consider passing '-c:s copy' and verifying whether FFmpeg can map the subtitle stream, or extract the captions separately before conversion.