MyMediaTools

Convert WTV to MP4 — Free Online Tool

Convert WTV recordings from Windows Media Center into MP4 files using H.264 video and AAC audio — formats that play on virtually any modern device or platform. WTV files are tied to the Windows ecosystem, and this tool breaks them free by re-encoding the broadcast capture into a universally compatible MP4 container with web-optimized faststart metadata.

FFmpeg Command

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Estimated output:

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How It Works

WTV files store recorded broadcast TV content using MPEG-2 or VC-1 video with AC-3 or MP2 audio, wrapped in a Microsoft-proprietary container. This conversion fully re-encodes the video stream using the H.264 (libx264) codec at CRF 23, which provides an excellent balance between file size and visual quality for typical broadcast source material. The audio is transcoded from AC-3 or MP2 to AAC at 128k bitrate. The output MP4 container adds the -movflags +faststart flag, which relocates the moov atom to the beginning of the file — essential for progressive playback and streaming. Because this is a full transcode (not a remux), it takes more processing time but ensures maximum compatibility across devices that cannot read WTV or its native codecs.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg program. When run via this browser tool, it executes inside a WebAssembly (FFmpeg.wasm) sandbox — no data leaves your machine. The same command can be pasted into a terminal on any desktop with FFmpeg installed to process files over 1GB.
-i input.wtv Specifies the input WTV file recorded by Windows Media Center. FFmpeg will automatically detect and demux the internal broadcast streams — whether MPEG-2 or VC-1 video, and AC-3, MP2, or other audio — from the Microsoft-proprietary WTV container.
-c:v libx264 Re-encodes the video stream using the H.264 codec (libx264). This is necessary because WTV's native MPEG-2 or VC-1 video is not natively supported in MP4 containers and requires transcoding to H.264, which is universally supported across devices, browsers, and platforms.
-c:a aac Transcodes the audio from the WTV file's native broadcast audio (typically AC-3 or MP2) to AAC, which is the standard audio codec for MP4 files and is supported natively on iOS, Android, browsers, and all major media players.
-crf 23 Sets the Constant Rate Factor for H.264 encoding to 23, which is the libx264 default and delivers good visual quality for broadcast TV source material. Lower values (e.g., 18) produce better quality at larger file sizes; higher values (e.g., 28) reduce file size with some visible quality loss.
-b:a 128k Sets the AAC audio bitrate to 128 kilobits per second. This is appropriate for stereo TV audio, though if the original WTV recording contains AC-3 5.1 surround sound, you may want to increase this to 192k or 256k to better preserve the multichannel mix after transcoding.
-movflags +faststart Moves the MP4 moov atom to the start of the output file after encoding completes. This is essential for web playback and streaming, allowing the video to begin playing before the full file is downloaded — particularly valuable for large WTV recordings that may run to several gigabytes after conversion.
output.mp4 Defines the output file as an MP4 container. FFmpeg infers the container format from the .mp4 extension and packages the re-encoded H.264 video and AAC audio into this widely compatible MPEG-4 Part 14 wrapper.

Common Use Cases

  • Transferring recorded TV shows from a Windows Media Center PC to an iPhone, iPad, or Android device for offline viewing
  • Uploading a recorded broadcast or live TV capture to YouTube, Vimeo, or another video platform that does not accept WTV files
  • Archiving old Windows Media Center recordings before decommissioning a Windows 7 or Windows Vista machine where the WTV format will no longer be accessible
  • Importing a recorded TV segment into a video editor like DaVinci Resolve, Adobe Premiere, or Final Cut Pro, which may not natively support WTV or its embedded VC-1/MPEG-2 streams
  • Sharing a recorded sports event, news segment, or documentary with someone who does not have Windows Media Center software installed
  • Playing back a WTV recording on a smart TV, media player (Plex, Kodi, VLC), or game console that requires standard H.264/MP4 input

Frequently Asked Questions

Yes, there is some quality loss because this is a full transcode — the original broadcast video (typically MPEG-2 or VC-1) is decoded and re-encoded to H.264. However, at the default CRF 23 setting, the quality loss is minimal and generally imperceptible for standard-definition or high-definition broadcast content. If you want higher fidelity, lower the CRF value (e.g., CRF 18) in the FFmpeg command, which increases quality at the cost of a larger file size.
WTV files store rich broadcast metadata including program title, channel, episode description, and air date using Microsoft's proprietary metadata schema. Standard FFmpeg conversion to MP4 may not carry over all of this metadata, as MP4 uses different metadata containers (iTunes-style atoms). Basic stream metadata may be preserved, but DVR-specific fields like channel name and broadcast schedule data will likely be lost. If metadata preservation is critical, consider using tools like MCEBuddy or dvbcut as a preprocessing step before converting.
The default FFmpeg command maps the first audio track only. WTV files recorded from broadcast TV often contain Secondary Audio Program (SAP) tracks for alternate languages or descriptive audio. To include all audio tracks in the output MP4, you can modify the command to add '-map 0:v -map 0:a' before the output filename, which explicitly maps all video and audio streams from the input. MP4 supports multiple audio tracks, so this is a valid approach.
WTV files often contain high-bitrate MPEG-2 video as originally broadcast, which can be quite large. Re-encoding to H.264 at CRF 23 typically produces significantly smaller files because H.264 achieves much better compression than MPEG-2 at equivalent quality. However, if the original WTV used VC-1 at a lower bitrate than what CRF 23 produces for that content, the MP4 could end up larger. Adjusting the CRF value (higher = smaller file, lower = larger file) lets you control this tradeoff directly.
Yes. On Windows, you can run a batch loop in Command Prompt: 'for %f in (*.wtv) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "%~nf.mp4"'. On Linux or macOS, use: 'for f in *.wtv; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "${f%.wtv}.mp4"; done'. This is especially useful when archiving an entire Windows Media Center library in one pass.
The -movflags +faststart flag moves the MP4 file's moov atom (the index that describes where all media data is located) from the end of the file to the beginning. Without it, a video player or browser must download the entire file before it can start playing. With faststart, the file can begin playing almost immediately during a progressive download or stream. For archival-only use where you will always play from local storage, it is optional — but it is recommended as a best practice for any MP4 you might share or upload.

Technical Notes

WTV (Windows Television) is a container format exclusive to Windows Vista/7/8 Media Center, and its internal codec landscape is heterogeneous depending on the broadcast source: recordings from over-the-air ATSC typically contain MPEG-2 video with AC-3 or MP2 audio, while ClearQAM cable recordings may use VC-1 video. FFmpeg can demux and decode both of these stream types, making it capable of handling the full range of WTV recordings. The output H.264 video at CRF 23 is well-suited for broadcast source material, which rarely benefits from CRF values below 18 due to the inherent compression artifacts already present in the broadcast signal itself. The AAC audio at 128k is a substantial downgrade from AC-3 surround sound if the original recording contains 5.1 audio — users who want to preserve surround sound should change -c:a to 'aac' with -b:a 192k or higher, or use -c:a copy if the source audio is already AAC-compatible. The -movflags +faststart flag is particularly important here because WTV files are large and the resulting MP4 may be used in streaming or sharing contexts. Subtitle tracks embedded in WTV (typically DVB or ATSC closed captions) are not automatically mapped by the default command; adding '-c:s mov_text' and '-map 0:s?' can attempt to include them, though caption format conversion from broadcast formats to MP4's mov_text subtitle format may have compatibility limitations.

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