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VFW_E_NEED_OWNER
Meaning
Windows documents VFW_E_NEED_OWNER as “This object can only be created as an aggregated object”. In practical terms, it is returned when a DirectShow object can be created only as part of COM aggregation and the caller requested a standalone instance.
Where the failure belongs
This result belongs to DirectShow filter-graph processing. The relevant condition is that a DirectShow object can be created only as part of COM aggregation and the caller requested a standalone instance.
Likely causes
- Possible cause 1: CoCreateInstance is called with no outer unknown for an aggregate-only helper.
- Possible cause 2: a filter constructs an inner object through the wrong factory path.
- Possible cause 3: aggregation rules are violated by requesting a non-IUnknown interface during creation.
Evidence to collect
- Capture 1: CLSID, requested IID and outer IUnknown pointer.
- Capture 2: the class factory call path and controlling-unknown identity.
- Capture 3: whether the owning filter uses the documented aggregate construction helper.
Diagnostic sequence
- Confirm that the observed path matches this condition: a DirectShow object can be created only as part of COM aggregation and the caller requested a standalone instance.
Correct handling and retry
- Corrective action 1: create the object through its intended owner and pass the controlling unknown.
- Corrective action 2: request IUnknown first when COM aggregation requires it.
- Corrective action 3: do not register aggregate-only implementation helpers as standalone application components.
Retry guidance. Retry only with the correct aggregation parameters; repeated standalone activation cannot succeed.
Practical scenario
A custom filter activates an internal aggregate-only helper directly from application code; constructing it inside the filter removes it.
Difference from nearby HRESULTs
CLASS_E_NOAGGREGATION rejects unsupported aggregation, while it requires aggregation that the caller omitted.
Official Microsoft references
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