Free online WTV to ASF converter

Windows Media Center recordings use WTV, while some older Windows video software and devices expect ASF or WMV-compatible media. Converting the recording is also useful when an editor cannot open the WTV container or when you need a more widely supported file for playback and archiving.

What the WTV format is

WTV is the Windows Recorded TV Show container used primarily by Windows Media Center in Windows Vista and Windows 7. It stores broadcast or cable television recordings together with video, audio, program metadata, captions, and electronic program guide information.

Depending on the broadcast and Windows Media Center configuration, a WTV file can contain MPEG-2, H.264, AC-3, AAC, or other streams. Some recordings are copy-protected; encrypted WTV files generally cannot be converted unless the protection is supported and the user has the required playback rights.

What the ASF format is

ASF, or Advanced Systems Format, is a Microsoft container designed for streaming, network delivery, seeking, and synchronized audio and video. Files commonly use the .asf extension, although WMV video and WMA audio are also commonly carried in ASF-based files.

ASF is useful with older Windows Media software, applications that specifically request an ASF container, and systems built around WMV or WMA codecs. The container itself does not determine file size; size depends mainly on the selected video and audio codecs, resolution, frame rate, and bitrates.

How to actually convert WTV to ASF

FFmpeg is the most flexible desktop option because it can read unprotected WTV recordings and write ASF files with WMV/WMA streams. Install a current FFmpeg build, place the WTV file in an accessible folder, and run:

ffmpeg -i input.wtv -c:v wmv2 -q:v 3 -c:a wmav2 -b:a 160k output.asf

This command decodes the WTV streams and creates an ASF file using the WMV2 video codec and WMA2 audio codec. Replace input.wtv and output.asf with the actual filenames; quote each path if it contains spaces:

ffmpeg -i "Recorded show.wtv" -c:v wmv2 -q:v 3 -c:a wmav2 -b:a 160k "Recorded show.asf"

For a smaller output, specify a lower video bitrate, for example:

ffmpeg -i input.wtv -c:v wmv2 -b:v 1800k -c:a wmav2 -b:a 128k output.asf

For a faster attempt without re-encoding, test stream copying first:

ffmpeg -i input.wtv -c copy output.asf

Stream copying works only when every source codec and stream feature is accepted by the ASF muxer and the target player. If FFmpeg reports an unsupported codec, incompatible stream, or playback produces no picture or sound, use the WMV2/WMA2 transcoding command instead.

For a no-installation option, use the free converter on 101convert.com, upload the unprotected WTV file, select ASF as the output format, start the conversion, and download the resulting file. Large recordings may take longer to upload and process, and protected recordings may still be rejected.

Quality, compatibility, and limitations

• Transcoding changes the video and audio and can reduce quality. The -q:v 3 setting favors quality over size; use a bitrate setting when a predictable file size is required.
• WTV recordings are often interlaced television video. Do not deinterlace automatically if the target device handles interlaced content correctly. If progressive output is required, add a filter such as -vf yadif, which increases processing time and changes the picture.
• ASF has weaker support for modern codecs and advanced WTV features than newer containers. Captions, EPG metadata, chapter information, multiple audio tracks, and recording-specific metadata may not survive conversion.
• Use a current media player to verify the output, then test it in the specific legacy application or device that requires ASF. A file with an .asf extension is not necessarily compatible if it contains codecs that the target system cannot decode.