What does HRESULT 0x0004027E (VFW_S_NOPREVIEWPIN) mean?

 
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VFW_S_NO_STOP_TIME VFW_S_DVD_NON_ONE_SEQUENTIAL

VFW_S_NOPREVIEWPIN

Capture graph provides preview by splitting the capture stream

VFW_S_NOPREVIEWPIN is HRESULT 262782 (0x0004027E) from Video for Windows. The documented description is “There was no preview pin available, so the capture pin output is being split to provide both capture and preview.” The high-order severity bit is clear, so this is a success result, but it carries more information than plain S_OK.

No dedicated preview pin was available, so graph building created preview behavior by splitting the capture-pin output.

Where the result is encountered

  • This result can appear in ICaptureGraphBuilder2 preview construction; record the producing interface and method.
  • This result can appear in capture devices exposing only a capture pin; record the producing interface and method.
  • It can appear in applications requesting simultaneous preview and recording; record the producing interface and method.

Diagnostic sequence

  • Capture the raw HRESULT 0x0004027E immediately after the returning method and record whether the caller used SUCCEEDED, FAILED, equality testing, or exception translation.
  • Verify the method-specific state: the inserted splitter path does not alter capture format, timing, or device performance beyond acceptable limits.

State to verify

The central question is whether the inserted splitter path does not alter capture format, timing, or device performance beyond acceptable limits.

Correct handling, retry, and recovery

Accept the synthesized preview when performance is adequate. If capture quality drops, disable preview or use hardware with a dedicated preview path instead of assuming the graph is equivalent.

Evidence to preserve

  • Preserve device filter and pin categories.
  • Preserve resulting graph topology.
  • Preserve capture and preview media types.
  • Preserve CPU and dropped-frame metrics.
  • Preserve recorded output validation.

Difference from nearby HRESULT values

S_OK may mean a real preview pin was used; it documents that preview was synthesized from capture output.

Developer and administrator guidance

Practical validation scenario

A USB camera exposes only PIN_CATEGORY_CAPTURE. The capture graph builder inserts a splitter for preview; testing confirms the recorded stream keeps its expected frame rate under preview load.

References

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