What does HRESULT 0x8004021B (VFW_E_NOT_OVERLAY_CONNECTION) mean?

VFW_E_NOT_OVERLAY_CONNECTION

Meaning

Windows documents VFW_E_NOT_OVERLAY_CONNECTION as “Current pin connection is not using the IOverlay transport”. In practical terms, it is returned when the current DirectShow pin connection does not use the IOverlay transport required by the requested overlay operation.

Evidence to collect

• Capture 1: connected peer and negotiated transport interfaces.
• Capture 2: pin media type and renderer CLSID.
• Capture 3: graph-building decision that selected the current renderer.

Where the failure belongs

This result belongs to DirectShow filter-graph processing. The relevant condition is that the current DirectShow pin connection does not use the IOverlay transport required by the requested overlay operation.

Likely causes

• Possible cause 1: the graph negotiated memory-sample transport instead of overlay transport.
• Possible cause 2: a renderer was replaced without updating overlay-specific control code.
• Possible cause 3: the pin is connected but to a component that does not implement IOverlay.

Diagnostic sequence

1. Confirm that the observed path matches this condition: the current DirectShow pin connection does not use the IOverlay transport required by the requested overlay operation.

Correct handling and retry

• Corrective action 1: query the active connection before issuing overlay methods.
• Corrective action 2: build the graph with an overlay-capable renderer when required.
• Corrective action 3: use sample-based presentation logic for IMemInputPin connections.

Retry guidance. Retry only after reconnecting through an overlay transport; the current connection cannot be converted by repeating the same call.

Difference from nearby HRESULTs

VFW_E_NOT_SAMPLE_CONNECTION is the complementary case for code requiring IMemInputPin transport.

Practical scenario

A legacy application assumes its renderer uses overlay after Windows selects a sample-based renderer; detecting the negotiated transport prevents it.

Official Microsoft references

• Microsoft: DirectShow error and success codes
• Microsoft: IOverlay
• Microsoft: DirectShow filters and pins