71 lines
2.3 KiB
C
71 lines
2.3 KiB
C
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/**
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* fc_client.h — Consumer-side framecache client library.
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*
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* Usage:
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* fc_consumer_t *c = fc_consumer_open("deltacast-zampp3-0");
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* fc_frame_ref_t ref;
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* while (fc_consumer_read(c, &ref, 2000) == FC_OK) {
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* // ref.data valid until next fc_consumer_read call
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* process_frame(ref.data, ref.size, ref.pts_us);
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* }
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* fc_consumer_close(c);
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*
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* Each consumer tracks its own read_cursor — multiple consumers on the same
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* slot are fully independent and never block each other or the writer.
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*
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* If a consumer falls more than ring_depth frames behind the writer its cursor
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* is snapped to the latest frame and FC_DROPPED is returned once.
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*/
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#pragma once
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#include <stdint.h>
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#include <stddef.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Return codes */
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#define FC_OK 0
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#define FC_TIMEOUT 1 /* no new frame within timeout_ms */
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#define FC_DROPPED 2 /* consumer fell behind; cursor snapped to latest */
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#define FC_ERROR -1
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typedef struct fc_consumer fc_consumer_t;
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typedef struct {
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const uint8_t *data; /* zero-copy pointer into shm ring — valid until next read */
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uint32_t size; /* bytes */
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uint64_t pts_us; /* presentation timestamp (microseconds) */
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uint64_t wall_us; /* wall clock at write time (microseconds) */
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uint64_t seq; /* write_cursor value for this frame */
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} fc_frame_ref_t;
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/**
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* Open a consumer handle for the named slot.
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* Polls the slot shm file until it appears (up to wait_ms milliseconds).
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* Returns NULL if slot not found within wait_ms or on error.
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*/
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fc_consumer_t *fc_consumer_open(const char *slot_id, uint64_t wait_ms);
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/**
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* Read the next frame.
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* Blocks up to timeout_ms waiting for a new frame (via semaphore).
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* Returns FC_OK, FC_TIMEOUT, FC_DROPPED, or FC_ERROR.
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* On FC_OK or FC_DROPPED the ref fields are populated.
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*/
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int fc_consumer_read(fc_consumer_t *c, fc_frame_ref_t *ref, uint64_t timeout_ms);
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/** Close the consumer handle. Does NOT destroy the slot. */
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void fc_consumer_close(fc_consumer_t *c);
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/** Current write_cursor of the slot (approximate — no lock). */
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uint64_t fc_consumer_write_cursor(fc_consumer_t *c);
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/** Frames dropped by this consumer since open. */
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uint64_t fc_consumer_dropped(fc_consumer_t *c);
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#ifdef __cplusplus
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}
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#endif
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