How to Fix “To Play This Video You Need a New Codec” Error?

On Windows 10/11, messages such as “To play this video, you need a new codec” usually appear when a media app cannot decode the video or audio stream stored inside the file. A filename extension such as .mp4, .mov, .avi, or .mkv only tells you the container type; it does not guarantee that the codec inside is supported by the app.

That is also why the old Photos Video Editor or Photos Legacy could show “You need an extension to use this file” or “We can't read this file” when importing certain clips. HEVC/H.265 is a common example: the container may look familiar, but the app can still need an additional HEVC decoder before it can play or edit the video.

The three fixes below cover both playback errors and similar video-import problems caused by unsupported codecs or missing Windows media extensions.

If you do not know which codec or extension is missing, or you need the same file to work in both a player and a video editor, the simplest solution is often to transcode the video to a widely supported codec. Simply renaming the filename extension does not change the codec inside. To this end, the easy-to-use Windows batch video converter - WonderFox HD Video Converter Factory Pro - can convert problematic files to more compatible formats and codecs with 500+ predefined presets.

DownloadDownload the versatile toolkit and follow the steps below. For broad Windows compatibility, MP4 with H.264 video and AAC audio is a practical default when you are unsure what to choose.

Step 1. Launch HD Video Converter Factory Pro and open “Converter” option.

Step 2. Drag and drop the video files that trigger a codec, extension, playback, or import error.

Step 3. Click the “Format Profile” image on the right side to open the full preset list. Navigate to the “Video” category and choose a format supported by your target app.

👉 If you just want a safe, widely compatible choice for playback or editing on Windows, select an MP4 profile using H.264 video and AAC audio.

Optional. Open “Parameter Settings” window to change video bit rate, encoder, resolution, frame rate, etc. at will.

Step 4. Choose a destination path and press the “Run” button to start the conversion.

This can resolve “To play this video, you need a new codec”, “You need a new codec to play this item”, and codec-related “You need an extension to use this file” errors.

Also Read: 0xc004f011 Error | Plex Conversion Failed Error | Clipchamp Not Working

If the error points to a specific codec or Windows media extension, installing the required component can be the most direct fix. Microsoft lists several additional codec packages for Media Player on Windows 10/11:

• MPEG-2 Video Extension

• HEVC Video Extensions

• VP9 Video Extensions

• AV1 Video Extension

• Web Media Extensions

For an HEVC/H.265 video, the HEVC extension is the relevant one. The HEIF Image Extension is for HEIF/HEIC images, so you do not need it just to play an ordinary HEVC video. Also, Store availability or pricing can vary, so it is better to check the current Microsoft Store listing instead of relying on an old fixed price.

If you use a Windows 10/11 N edition, install the Media Feature Pack from Settings > Apps > Optional features first, because N editions do not include the full set of Windows media technologies by default.

Extra note for Windows 11: Starting with Windows 11 version 24H2, AC-3 (Dolby Digital) is no longer included by default on new installations. Some manufacturers preinstall it, and systems upgraded from earlier Windows versions may retain it. If a video opens but its AC-3 audio does not play, the missing audio decoder may be the real problem.

About K-Lite Codec Pack: K-Lite is still useful for players that use DirectShow, and the Standard package includes MPC-HC. However, the modern Media Player in Windows 10/11 uses Media Foundation rather than K-Lite's DirectShow codecs. So, if your goal is to add support directly to the modern Media Player, use the official Microsoft codec extensions above. If you install K-Lite, it is often more practical to play the file with the included MPC-HC.

For a playback-only problem, trying another media player can be faster than changing Windows itself. VLC, PotPlayer, MPC-HC, KMPlayer, and Kodi include broader decoding support than many built-in apps.

For video editing, Microsoft now recommends Clipchamp as the official Windows editor. It accepts many common container formats and automatically converts some files before editing, but unsupported codecs can still cause import errors. For example, Clipchamp currently does not support AV1-encoded video.

If another player or editor still cannot open the file, go back to Solution 1 and transcode it to a more compatible format first.

Q: Why do I need a codec to watch videos?

A: A codec tells software how to decode the compressed video or audio stream inside a media file. A familiar filename extension does not guarantee that the codec inside is supported, which is why one MP4 may play normally while another MP4 triggers a codec error.

Q: What does “You need an extension to use this file” mean?

A: In the old Photos Video Editor or Photos Legacy, this message often meant that Windows could see the file but did not have the decoder needed for the codec inside it. Installing the correct media extension, using another app, or transcoding the video can solve the problem. The current Photos app no longer includes the previous Video Editor; Microsoft recommends Clipchamp for Windows video editing.

Q: Can I play HEVC videos without downloading a new codec?

A: Yes, if you use a media player with built-in HEVC decoding support. Otherwise, you can install HEVC support for Windows or transcode the video to H.264 or another codec your app already supports.

Q: Is there a universal codec that can play every video?

A: No single codec handles every format. Some third-party players bundle a broad range of decoders, while Windows apps may rely on built-in Media Foundation support plus optional Microsoft Store extensions. When compatibility matters across many devices and apps, converting the file to a widely supported codec is often the most predictable solution.

That's all. Whether Windows says “To play this video, you need a new codec”, “You need a new codec to play this item”, or “You need an extension to use this file”, the real issue is usually codec compatibility rather than the filename extension itself. You can transcode the video, install the required Windows media extension, or switch to a player or editor with broader format support. These same steps can also help with many other unsupported video format errors. Thanks for reading!