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doc: explain clock/latency more

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Update SPA_IO_Clock/Position documentation.

Explain some IOs are currently unused in PW.

Explain meaning of latency.
This commit is contained in:
Pauli Virtanen 2024-01-27 13:00:03 +02:00 • committed by Wim Taymans
parent 21392d327f
commit 97db4a68a7
2 changed files with 77 additions and 27 deletions
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31
spa/include/spa/param/latency.h
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@ -16,14 +16,30 @@ extern "C" {
#include <spa/param/param.h>
/** properties for SPA_TYPE_OBJECT_ParamLatency */
/**
* Properties for SPA_TYPE_OBJECT_ParamLatency
*
* The latency indicates:
*
* - for playback: time delay between start of a graph cycle, and the rendering of
* the first sample of that cycle in audio output.
*
* - for capture: time delay between start of a graph cycle, and the first sample
* of that cycle having occurred in audio input.
*
* For physical output/input, the latency is intended to correspond to the
* rendering/capture of physical audio. However, hardware internal rendering delay is
* usually not included e.g. for ALSA.
*
* The latency values are adjusted by \ref SPA_PROP_latencyOffsetNsec if present.
*/
enum spa_param_latency {
SPA_PARAM_LATENCY_START,
SPA_PARAM_LATENCY_direction, /**< direction, input/output (Id enum spa_direction) */
SPA_PARAM_LATENCY_minQuantum, /**< min latency relative to quantum (Float) */
SPA_PARAM_LATENCY_maxQuantum, /**< max latency relative to quantum (Float) */
SPA_PARAM_LATENCY_minRate, /**< min latency (Int) relative to rate */
SPA_PARAM_LATENCY_maxRate, /**< max latency (Int) relative to rate */
SPA_PARAM_LATENCY_minRate, /**< min latency (Int) relative to graph rate */
SPA_PARAM_LATENCY_maxRate, /**< max latency (Int) relative to graph rate */
SPA_PARAM_LATENCY_minNs, /**< min latency (Long) in nanoseconds */
SPA_PARAM_LATENCY_maxNs, /**< max latency (Long) in nanoseconds */
};
@ -41,11 +57,16 @@ struct spa_latency_info {
#define SPA_LATENCY_INFO(dir,...) ((struct spa_latency_info) { .direction = (dir), ## __VA_ARGS__ })
/** properties for SPA_TYPE_OBJECT_ParamProcessLatency */
/**
* Properties for SPA_TYPE_OBJECT_ParamProcessLatency
*
* The processing latency indicates logical time delay between a sample in an input port,
* and a corresponding sample in an output port, relative to the graph time.
*/
enum spa_param_process_latency {
SPA_PARAM_PROCESS_LATENCY_START,
SPA_PARAM_PROCESS_LATENCY_quantum, /**< latency relative to quantum (Float) */
SPA_PARAM_PROCESS_LATENCY_rate, /**< latency (Int) relative to rate */
SPA_PARAM_PROCESS_LATENCY_rate, /**< latency (Int) relative to graph rate */
SPA_PARAM_PROCESS_LATENCY_ns, /**< latency (Long) in nanoseconds */
};