Fix NS_E_WMG_RATEUNAVAILABLE 0XC00D104A

Windows Media Player throws this when you try to change playback speed and the codec or player can't handle it. Start with the quick fix, then move up.

Quick Fix (30 seconds) — Switch to a Different Speed

Before you touch anything else, try this. Click the Now Playing button (bottom-right, looks like a monitor) or press Alt+1 to get out of the library view. Then right-click the video, go to Enhancements > Play Speed Settings. Drag the slider to a different speed — say 1.2x or 0.8x — and play. Sometimes WMP just trips over a specific speed value, and moving it slightly gets it working again.

If that still errors, change the speed before hitting play, not during. WMP 12 is finicky about changing speed mid-stream on certain files. Stop the file, set the speed, then press play.

That's the simplest fix. If it doesn't work, you've got a codec problem, and that's the next step.

Moderate Fix (5 minutes) — Replace the Codec

The culprit here is almost always an outdated or missing codec. WMP relies on DirectShow filters to decode video, and if the filter doesn't support rate changes (especially for ASF/WMV files), you get 0XC00D104A the second you touch the speed slider.

Don't bother with codec packs — they cause more problems than they solve. Here's what you actually do:

Press Win+R, type appwiz.cpl, hit Enter.
Look for any codec packs like K-Lite, CCCP, or ffdshow. If you see one, uninstall it. Yes, seriously. They're usually the reason your codecs are broken in the first place.
Reboot, then install K-Lite Codec Pack Basic — the Basic version is enough. Make sure you pick the Standard install type and let it register its filters with Windows.

If you're on Windows 10 or 11, you should also check the Media Feature Pack. If you're running an N edition of Windows, that pack is missing and WMP doesn't have the right codecs at all. Go to Settings > Apps > Optional Features and add Media Feature Pack. That fixes a huge chunk of WMP errors on N editions.

Test the speed change again. If it still fails, we go deeper.

Advanced Fix (15+ minutes) — Re-register the Codecs and Check the File

Sometimes the codec registration gets corrupted. Re-registering the Windows Media components can clear that up. Run an admin Command Prompt and type:

regsvr32 wmvdmoe2.dll
regsvr32 wmvcore.dll
regsvr32 wmp.dll

You'll get a success message for each. Reboot and test.

If you're still hitting the error, the problem might be the file itself. WMP can't change speed on certain container formats — like a WMV file with a variable bitrate that wasn't encoded properly, or an AVI with an odd resolution. Check the file's properties: right-click > Properties > Details. Look at the video codec. If it says WMV3 or VC-1, you should be fine. If it says MJPEG or DV Video, that's your problem — those codecs don't support rate changes at all in WMP.

For files like that, the real fix is to transcode the file to a modern format like MP4 (H.264). Use HandBrake — it's free, and the default settings work fine:

Download and install HandBrake.
Open the problem file.
Pick the Fast 1080p30 preset (or whatever matches your resolution).
Hit Start Encode. It takes a few minutes depending on file length.

Once it's converted, open the MP4 in WMP and try the speed change again. It'll work — H.264 handles rate changes smoothly because the DirectShow filter for it (Microsoft's built-in one) supports it.

One more thing: if you're playing a DVD or a live stream, speed changes are never going to work. The error might pop up for those, but it's not really an error — it's WMP telling you it can't do that. Use a different player for that stuff.

Bottom line: 90% of the time this error is a codec issue, not a WMP issue. Fix the codec, fix the problem. Skip the registry hacks and the “reinstall Windows” advice you'll see elsewhere — that's overkill.