Refactor: Cache pipeline TX frame period at create - #1689
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The three tx_st*p_if_frame_late() callbacks derived their DROP_WHEN_LATE grace window per frame as NS_PER_S / st_frame_rate(ops.fps): a float division and a table search in a transport callback, and a divide by zero for an fps outside the timing table (Coverity CID 558964). That zero is unreachable today — the session layer rejects an unknown fps at attach — so this is hardening, not a defect fix. New st_frame_period_ns() derives the period from the exact rational rate; its truncated result is bit-identical to the float form for all 11 timing-table entries. Signed-off-by: Wilczynski, Andrzej <andrzej.wilczynski@intel.com>
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The three tx_st*p_if_frame_late() callbacks derived their DROP_WHEN_LATE grace window per frame as NS_PER_S / st_frame_rate(ops.fps): a float division and a table search in a transport callback, and a divide by zero for an fps outside the timing table (Coverity CID 558964). That zero is unreachable today — the session layer rejects an unknown fps at attach — so this is hardening, not a defect fix. New st_frame_period_ns() derives the period from the exact rational rate; its truncated result is bit-identical to the float form for all 11 timing-table entries.