Fix NS_E_INTERLACEMODE_MISMATCH 0XC00D1BAB in Windows Media Encoder

This error pops up when you're encoding video and two streams for the same source have different interlace settings. Fix is to match them or force the encoder.

When does this error show up?

You're encoding video with Windows Media Encoder (WME) 9 series or Expression Encoder. You set up multiple audiences — say one for high bitrate and one for low bitrate — from the same source file. You hit encode, and boom: NS_E_INTERLACEMODE_MISMATCH (0XC00D1BAB). The exact message says "The same source index in different audiences should have the same interlace mode."

I see this most often with interlaced source material like DV camcorder footage or old TV captures. But it can happen with progressive sources if the encoder gets confused by your audience setup.

What's actually going on?

The encoder is complaining that you have two or more output streams using the same source index but with different interlace settings. In plain English: you told it to make two versions from the same video but said one should be interlaced and the other progressive. WME doesn't allow that — it insists all audiences sharing a source must use identical interlace mode.

The culprit here is almost always the per-audience video settings dialog. You set interlace to "maintain interlaced" for your high-bitrate audience and "deinterlace" for the low-bitrate one. Or you left defaults and didn't notice one audience inherited a different setting.

Another trigger: using a capture card that feeds interlaced video, then manually overriding the interlace mode in one audience but not the others. The encoder checks all audiences against each other, and any mismatch kills the encode.

How to fix it

Skip the registry hacks or codec reinstalls — they never fix this. The fix is all in the encoder settings. Here's the step-by-step.

Step 1: Open your session file or project

In Windows Media Encoder, load your .wme file or start a new session. In Expression Encoder, open your project file.

Step 2: Go to the audience properties

In WME, click the Output tab. You'll see your list of audiences (like "Windows Media Audio/Video High"). Right-click the first audience and choose Properties.

In Expression Encoder, go to the Output panel and click on the audience name to edit.

Step 3: Check the interlace mode for each audience

Inside the properties dialog, look for the Video section. You'll see an option called Interlace Mode or Deinterlace. It's usually set to one of these:

Maintain interlaced — keeps the video interlaced
Deinterlace — converts to progressive
Auto — lets the encoder decide

Write down what each audience has. If any differ, that's your problem.

Step 4: Make them all the same

Change every audience to use the same interlace mode. I recommend one of these approaches:

All set to Auto — the encoder picks based on source. This works most of the time.
All set to Deinterlace — if you want progressive output across all audiences.
All set to Maintain interlaced — only if your source is truly interlaced and you need that preserved.

Don't mix. If you need different modes for different use cases, you'll need to create separate encoding sessions — one per interlace setting.

Step 5: Apply and encode

Click OK on all dialogs, then start the encode. The error should not reappear.

What if it still fails?

Three things to check.

First: Did you use any third-party plugins or filters that modify interlace detection? Some plugins override the encoder's interlace flag. Remove them and try again.

Second: Is your source file itself flagged with inconsistent interlace metadata? Use MediaInfo to check the "Interlacement" field. If it says "Interlaced" but the encoder reads something else, you might need to remux the file with ffmpeg first:

ffmpeg -i input.ts -c copy -flags +ilme+ildct output.ts

This forces the interlace flags to be consistent.

Third: Are you encoding from a live capture source? Some capture cards report interlace mode differently per stream. In that case, set all audiences to Maintain interlaced and don't use Auto mode. The encoder will trust the capture card's signal.

If none of that works, you're probably dealing with a corrupt source file. Re-create it from the original media and try again. I've seen this once in 14 years — it's rare but happens.