What does HRESULT 0xC00D1B9B (NS_E_NUM_LANGUAGE_MISMATCH) mean?

NS_E_NUM_LANGUAGE_MISMATCH

Where the Encoder produces this result

0xC00D1B9B (NS_E_NUM_LANGUAGE_MISMATCH) identifies the same source index exposes different language counts across audiences. This is an Encoder validation error; a later “cannot start encoding” dialog can hide the original HRESULT.

A Windows Media Encoder profile declares content types and one or more audiences. Each audience maps source indexes to audio, video, script or file streams and must remain structurally consistent with the other audiences in a multiple-bit-rate profile.

What has already succeeded

Individual fields may be syntactically valid while the complete profile is inconsistent across audiences or does not match the source group. For example, one audience drops a secondary audio language but retains the shared source index. Reproduce the condition at the Encoder object that returned the HRESULT rather than treating it as a general codec or operating-system failure.

A controlled diagnostic sequence

1. Record 0xC00D1B9B, 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 index, language list and count for each audience.
3. Verify the profile, audience and stream topology precondition without changing the source, profile and output sink at the same time.
4. Run one controlled comparison that changes only the identified precondition: use the same number of language alternatives for that source index in all audiences.

Nearby HRESULTs that mean something else

Corrective action at the right layer

Do not repair a profile by deleting arbitrary audiences; export the .prx profile first and compare the same source index across every audience.

Technical references

• Adding an audience to an encoder profile.
• IWMEncAudienceObj.TotalBitrate.
• Retrieving the profile assigned to a source group.
• Detecting profile compatibility.