What does HRESULT 0xC00D1B72 (NS_E_NO_ACTIVE_SOURCEGROUP) mean?

NS_E_NO_ACTIVE_SOURCEGROUP

How to interpret the code in a real encoding session

0xC00D1B72 is named NS_E_NO_ACTIVE_SOURCEGROUP. Its practical scope is an operation that requires SourceGroupCollection.Active when no group is selected, which belongs to encoder state-machine sequencing rather than to every part of Windows Media playback or Windows itself.

Mechanism and point of failure

WMEncoder exposes configuration, preparation, running, paused, stopped and archival states. Properties that alter graph topology are normally set before Start, while statistics and some control operations are meaningful only after a session reaches the matching state.

The same method can be valid in one encoder state and rejected in another without any file, codec or network defect. A typical reproduction is: the last active group is deleted during configuration cleanup. This makes the first result from the Encoder more valuable than a later generic message.

Minimal experiment

1. Record 0xC00D1B72, 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-group count, Active value, prepared flags and the most recent group-removal or activation call.
3. Verify the encoder state-machine sequencing precondition without changing the source, profile and output sink at the same time.
4. Run one controlled comparison that changes only the identified precondition: select and prepare an existing source group before starting or switching.

Do not collapse these results together

What to change—and what to leave alone

Do not hide the ordering problem behind unconditional retries; log the transition sequence and make the operation occur at the documented lifecycle point.

Authoritative documentation

• WMEncoder.Start.
• Preparing a source group for encoding.
• WMEncoder.Flush.
• Saving a Windows Media Encoder configuration.