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VFW_E_NO_CLOCK
Meaning and numerical form
VFW_E_NO_CLOCK is HRESULT 2147746323 (0x80040213; signed -2147220973). AllStat records its meaning as “Cannot lock for synchronization because no clock has been defined”. In practical terms, it is returned when a DirectShow synchronization or advise operation requires a reference clock but the graph or filter has none.
The severity bit in 0x80040213 is set, so this result is a failure result rather than a success or informational status. Its facility is 4 (FACILITY_ITF) and its low 16-bit code is 531 (0x0213). Those fields classify the value but do not identify the component instance, call, object or input that produced it.
Likely causes
- Possible cause 1 for it: the graph deliberately selected no clock and a component still requests timed synchronization.
- Possible cause 2 for it: clock selection failed during graph setup.
- Possible cause 3 for it: a filter cached a clock that was removed or released.
Where the failure belongs
This result belongs to DirectShow filter-graph processing. DirectShow is a legacy, component-based media pipeline. Graph state, pin transport, negotiated media types, allocators, clocks, samples, renderers and source filters contribute separate contracts to the operation. The decisive condition is this: a DirectShow synchronization or advise operation requires a reference clock but the graph or filter has none. Record the first native producer instead of relying only on a framework exception translated several layers later.
Do not infer from this result alone that reinstalling, rebooting or repeating the whole workflow is appropriate. Because it can cross process and language boundaries, its correction depends on the object identity, lifecycle generation, input and state at the first failing call.
Diagnostic sequence
- Capture this result at the first native return and identify the exact object and method.
- Confirm that the observed path matches this the condition: a DirectShow synchronization or advise operation requires a reference clock but the graph or filter has none.
- compare the live state with the method contract before changing configuration.
- collect the code-specific evidence listed above and preserve any more specific preceding error.
- change one evidence-backed cause at a time, then repeat the smallest operation that can prove the correction.
- Add a regression check that distinguishes it from the related outcomes described below.
Evidence to collect
A useful it record includes the native API or interface method, component or CLSID, process and thread IDs, architecture, apartment where relevant, operation correlation ID, elapsed time, input identity, and the first state-changing event before failure. When diagnosing it, preserve IErrorInfo, an inner HRESULT, Win32 status, device event or provider message when available.
- Capture 1 for it: IMediaFilter::GetSyncSource result for the affected filter.
- Capture 2 for it: graph clock-selection events and clock CLSID.
- Capture 3 for it: advise time, stream time and graph state.
Telemetry for it should retain types, lengths, hashes, stable opaque identifiers and lifecycle generations while redacting content and credentials. This makes repeated incidents comparable without exposing media content, file paths, device identifiers or credentials.
Correction and retry boundary
- Corrective action 1 for it: assign a valid reference clock before timed operations.
- Corrective action 2 for it: support clockless execution only in components designed for it.
- Corrective action 3 for it: refresh clock references after graph reconstruction.
Retry guidance for it. Retry after setting the synchronization source; waiting longer cannot create a missing clock. A it retry must avoid this hazard: replay obsolete samples, duplicate graph changes or reuse interfaces from an earlier topology generation. It must also preserve the evidence needed to locate the original producer of it.
Difference from nearby HRESULTs
VFW_E_TIME_ALREADY_PASSED has a clock but rejects a past schedule, whereas it means timed scheduling has no clock source at all. Keep these outcomes separate in logs, exception mappings, user messages, dashboards and automated retry policy.
Practical scenario
A fast-as-possible transcoding graph disables its clock, but a custom renderer still schedules an advise; making that renderer clockless prevents it. The result scenario narrows the result to a reproducible contract boundary and supplies a concrete before-and-after test.
Developer and operational guidance
Code handling it should log the failed stage before cleanup, keep ownership and lifecycle transitions explicit, and avoid converting every failure into a generic message. Tests for it should cover the primary cause, one adjacent HRESULT and the retry boundary so a future change cannot turn a deterministic contract failure into an uncontrolled loop.
Operational repair for it should use supported filter installation, device, graph-building and renderer configuration paths. Avoid unsupported configuration edits or component replacement unless evidence identifies that layer. Retain the original trace and a post-fix trace so the result can be attributed and the change reversed.
Official Microsoft references
- Microsoft: DirectShow error and success codes
- Microsoft: DirectShow reference clocks
- Microsoft: IMediaControl
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