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mention the sound card clock and system clock difference in libpulse docs

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This commit is contained in:
Tanu Kaskinen 2017-10-19 21:22:15 +03:00
parent 7a7072557a
commit 50918e908b
2 changed files with 19 additions and 8 deletions
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19
src/pulse/def.h
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@ -641,8 +641,8 @@ typedef enum pa_subscription_event_type {
* pa_stream_update_timing_info() and pa_stream_get_timing_info(). The * pa_stream_update_timing_info() and pa_stream_get_timing_info(). The
* total output latency a sample that is written with * total output latency a sample that is written with
* pa_stream_write() takes to be played may be estimated by * pa_stream_write() takes to be played may be estimated by
* sink_usec+buffer_usec+transport_usec. (where buffer_usec is defined * sink_usec+buffer_usec+transport_usec (where buffer_usec is defined
* as pa_bytes_to_usec(write_index-read_index)) The output buffer * as pa_bytes_to_usec(write_index-read_index)). The output buffer
* which buffer_usec relates to may be manipulated freely (with * which buffer_usec relates to may be manipulated freely (with
* pa_stream_write()'s seek argument, pa_stream_flush() and friends), * pa_stream_write()'s seek argument, pa_stream_flush() and friends),
* the buffers sink_usec and source_usec relate to are first-in * the buffers sink_usec and source_usec relate to are first-in
@ -652,12 +652,19 @@ typedef enum pa_subscription_event_type {
* source_usec+buffer_usec+transport_usec-sink_usec. (Take care of * source_usec+buffer_usec+transport_usec-sink_usec. (Take care of
* sign issues!) When connected to a monitor source sink_usec contains * sign issues!) When connected to a monitor source sink_usec contains
* the latency of the owning sink. The two latency estimations * the latency of the owning sink. The two latency estimations
* described here are implemented in pa_stream_get_latency(). Please * described here are implemented in pa_stream_get_latency().
* note that this structure can be extended as part of evolutionary *
* API updates at any time in any new release.*/ * All time values are in the sound card clock domain, unless noted
* otherwise. The sound card clock usually runs at a slightly different
* rate than the system clock.
*
* Please note that this structure can be extended as part of evolutionary
* API updates at any time in any new release.
* */
typedef struct pa_timing_info { typedef struct pa_timing_info {
struct timeval timestamp; struct timeval timestamp;
/**< The time when this timing info structure was current */ /**< The system clock time when this timing info structure was
* current. */
int synchronized_clocks; int synchronized_clocks;
/**< Non-zero if the local and the remote machine have /**< Non-zero if the local and the remote machine have

8
src/pulse/stream.h
View file

@ -706,7 +706,9 @@ pa_operation* pa_stream_set_name(pa_stream *s, const char *name, pa_stream_succe
/** Return the current playback/recording time. This is based on the /** Return the current playback/recording time. This is based on the
* data in the timing info structure returned by * data in the timing info structure returned by
* pa_stream_get_timing_info(). * pa_stream_get_timing_info(). The returned time is in the sound card
* clock domain, which usually runs at a slightly different rate than
* the system clock.
* *
* This function will usually only return new data if a timing info * This function will usually only return new data if a timing info
* update has been received. Only if timing interpolation has been * update has been received. Only if timing interpolation has been
@ -738,7 +740,9 @@ pa_operation* pa_stream_set_name(pa_stream *s, const char *name, pa_stream_succe
int pa_stream_get_time(pa_stream *s, pa_usec_t *r_usec); int pa_stream_get_time(pa_stream *s, pa_usec_t *r_usec);
/** Determine the total stream latency. This function is based on /** Determine the total stream latency. This function is based on
* pa_stream_get_time(). * pa_stream_get_time(). The returned time is in the sound card clock
* domain, which usually runs at a slightly different rate than the
* system clock.
* *
* The latency is stored in \a *r_usec. In case the stream is a * The latency is stored in \a *r_usec. In case the stream is a
* monitoring stream the result can be negative, i.e. the captured * monitoring stream the result can be negative, i.e. the captured