What does HRESULT 0xC00D1BE9 (NS_E_MARKIN_UNSUPPORTED) mean?

NS_E_MARKIN_UNSUPPORTED

Diagnostic meaning beyond the standard text

For NS_E_MARKIN_UNSUPPORTED (0xC00D1BE9), the actionable event is MarkIn or MarkOut clipping is requested for a source type that does not support seeking to marks.

Why the session can reach this point

Windows Media Encoder builds a timeline for every selected source before samples enter the codec. Mark-in, mark-out, repeat and time-compression settings are therefore validated against the source duration and against each other before encoding begins.

A file that opens and reports a duration can still fail here because timeline validation happens after source discovery but before the first encoded sample. One concrete way to reach the condition is that a live device or custom streaming source receives file-style clip offsets.

Decision path

1. Record 0xC00D1BE9, the Encoder version and the exact API call or property access that returned it.
2. Export the current .wme or .prx configuration, then capture source type/scheme, seekability and configured MarkIn/MarkOut.
3. Verify the source timeline and clipping precondition without changing the source, profile and output sink at the same time.
4. Run one controlled comparison that changes only the identified precondition: remove marks or use a seekable source implementation.

Codes with similar symptoms but different owners

Safe recovery

Remove marks or use a seekable source implementation.

Do not re-encode or trim the only copy of the input while diagnosing the timeline; preserve the original duration and timestamps so the invalid interval can be reproduced.

Source material

• IWMEncSource.MarkOut.
• IWMEncSource.Repeat.
• Preparing a source group for encoding.
• Two-pass encoding.