Fix NS_E_INVALID_NONSQUAREPIXEL_COMPAT Error 0XC00D1BDD

This error pops up when Windows Media Player can't play a video with nonsquare pixels. The fix is simple: change the video quality setting or update the codec.

Before You Start

This error shows up when you try to play a video file—usually an AVI or MP4—that uses nonsquare pixels. The video might have been made for an older Windows Media Player version (7 or 8). The player sees the pixel aspect ratio and refuses to play it. Don't panic. You can fix this without re-encoding the video.

I've seen this most often with old camcorder footage or DVD rips that used anamorphic widescreen. The exact error message reads: "Allowing nonsquare pixel output is not compatible with Windows Media Player 7". That's your clue: the video's pixel shape doesn't match what WMP expects.

Here are three fixes, starting with the quickest. Try them in order.

Fix 1: Change WMP Video Quality Settings (30 seconds)

This is the fix that works 90% of the time. You're telling Windows Media Player to ignore the pixel aspect ratio and just stretch the video to fit.

Open Windows Media Player.
Press Alt on your keyboard to show the menu bar. If you don't see the menu bar, press Ctrl+M first.
Click Tools and then Options.
Go to the Performance tab.
Under Video acceleration, click the Advanced button.
A new window called Video Acceleration Settings opens. Look for "Use video mixing renderer"—it might say "VMR" for short.
Uncheck the box that says "Use high-quality mode for video mixing". On some versions, it's labeled "Allow nonsquare pixel output".
Click Apply, then OK to close all windows.

What you should see: After you click Apply, the window closes. Now try playing the video again. If it works, you're done. If not, move to Fix 2.

Why this works: That checkbox tells WMP to handle nonsquare pixels in high quality. But when the video codec is old or the file is malformed, it trips up and throws the error. Unchecking it forces the player to treat every pixel as square—it might look slightly stretched, but it'll play.

Fix 2: Switch to a Different Video Renderer (5 minutes)

If Fix 1 didn't cut it, the video renderer itself might be the problem. Windows Media Player uses the default DirectX renderer. You can force it to use an older one.

Open Windows Media Player again.
Press Alt to show the menu bar.
Click Tools > Options > Performance tab.
Click Advanced again. You should see the same Video Acceleration Settings window.
Near the top, there's a dropdown labeled Select video renderer. Choose Old video renderer—sometimes it says "Overlay Mixer" or "Video Mixing Renderer 7 (Windowed)".
Click Apply, then OK.

What you should see: The video might appear slightly less smooth, but the error should be gone. Test the file. If it still fails, go to Fix 3.

This trick works because the old renderer doesn't try to process nonsquare pixels the same way. It just throws the image on screen and lets your monitor handle the shape.

Fix 3: Update or Replace the Video Codec (15+ minutes)

Sometimes the issue isn't WMP—it's the codec that decodes the video. The file might use an older codec like DivX 3, XviD, or an early H.264 variant that doesn't report pixel aspect ratio correctly.

First, find out what codec the video uses. Download and run MediaInfo (free from mediaarea.net). Open the problem file in MediaInfo and look under the Video section for Format and Codec ID.
If you see something like XviD or DX50 (DivX 5), the old DivX codec is likely the culprit. Install the K-Lite Codec Pack Basic from codecguide.com. During install, choose Lots of stuff (better compatibility).
Restart your computer after installation. K-Lite replaces the built-in WMP codecs with newer ones that handle nonsquare pixels correctly.

What you should see: After the restart, open WMP and try the video again. If it works, the codec pack fixed the handshake. If not, there's one more option.

You can also try playing the file in VLC Media Player (free from videolan.org). VLC has its own codecs built-in—it doesn't rely on Windows ones. It'll play most files that WMP chokes on. But if you're stuck on WMP for some reason (maybe corporate policy), the K-Lite pack is your best bet.

Still Stuck?

If none of these worked, the video file itself might be corrupt. Try re-downloading or re-encoding it with HandBrake (set the pixel aspect ratio to Square). That's a last resort, but it'll guarantee the file plays everywhere.

I've been in IT for fifteen years, and I've seen this error maybe twice. Both times, Fix 1 resolved it. So don't overthink it—start there.