SpiDetermineSyncMaster

Determines the optimal master stream for a synchronization group based on hardware capabilities and timing granularity.

Syntax

#include <os2.h>

ULONG SpiDetermineSyncMaster(
  PHSTREAM phstreamMaster, /* Returns best master handle */
  PMASTER  paMasterList,   /* Array of candidate streams  */
  ULONG    ulNumMasters    /* Number of candidates        */
);

Parameters

phstreamMaster (PHSTREAM) - output

Pointer to the variable that receives the handle of the determined master stream.

paMasterList (PMASTER) - input

Array of MASTER structures containing handles of candidate streams.

ulNumMasters (ULONG) - input

The count of elements in the paMasterList array.

Return Value

rc

(ULONG) Returns 0 (NO_ERROR) on success, otherwise:

• ERROR_INVALID_STREAM: One of the handles is invalid.
• ERROR_MASTER_CONFLICT: Multiple streams have incompatible master-only flags.
• ERROR_NO_MASTER: No streams in the list are capable of being a master.
• ERROR_NO_SYNC: Target stream does not support synchronization.

Remarks

The function selects the master by comparing the sync pulse granularity (mmtimeSync) defined in the SPCB of each candidate. The stream with the finest (lowest) granularity is chosen to ensure the highest precision for the slave streams.

Related Functions

• SpiEnableSync
• SpiDisableSync

Example

HSTREAM hMasterResult;
MASTER  candidates[2];

candidates[0].hstreamMaster = hStreamAudio;
candidates[1].hstreamMaster = hStreamVideo;

if (!SpiDetermineSyncMaster(&hMasterResult, candidates, 2)) {
    /* Use hMasterResult in SpiEnableSync */
}