/* PipeWire */ /* SPDX-FileCopyrightText: Copyright © 2018 Wim Taymans */ /* SPDX-License-Identifier: MIT */ #ifndef PIPEWIRE_STREAM_H #define PIPEWIRE_STREAM_H #ifdef __cplusplus extern "C" { #endif /** \page page_streams Streams * * \see \ref pw_stream * * \section sec_overview Overview * * \ref pw_stream "Streams" are used to exchange data with the * PipeWire server. A stream is a wrapper around a proxy for a pw_client_node * with an adapter. This means the stream will automatically do conversion * to the type required by the server. * * Streams can be used to: * * \li Consume a stream from PipeWire. This is a PW_DIRECTION_INPUT stream. * \li Produce a stream to PipeWire. This is a PW_DIRECTION_OUTPUT stream * * You can connect the stream port to a specific server port or let PipeWire * choose a port for you. * * For more complicated nodes such as filters or ports with multiple * inputs and/or outputs you will need to use the pw_filter or make * a pw_node yourself and export it with \ref pw_core_export. * * Streams can also be used to: * * \li Implement a Sink in PipeWire. This is a PW_DIRECTION_INPUT stream. * \li Implement a Source in PipeWire. This is a PW_DIRECTION_OUTPUT stream * * In this case, the PW_KEY_MEDIA_CLASS property needs to be set to * "Audio/Sink" or "Audio/Source" respectively. * * \section sec_create Create * * Make a new stream with \ref pw_stream_new(). You will need to specify * a name for the stream and extra properties. The basic set of properties * each stream must provide is filled in automatically. * * Once the stream is created, the state_changed event should be used to * track the state of the stream. * * \section sec_connect Connect * * The stream is initially unconnected. To connect the stream, use * \ref pw_stream_connect(). Pass the desired direction as an argument. * * The direction is: * \li PW_DIRECTION_INPUT for a stream that *consumes* data. This can be a * stream that captures from a Source or a when the stream is used to * implement a Sink. An application will use a \ref PW_DIRECTION_INPUT * stream to record data. A virtual sound card will use a * \ref PW_DIRECTION_INPUT stream to implement audio playback. * * \li PW_DIRECTION_OUTPUT for a stream that *produces* data. This can be a * stream that plays to a Sink or when the stream is used to implement * a Source. An application will use a \ref PW_DIRECTION_OUTPUT * stream to produce data. A virtual sound card or camera will use a * \ref PW_DIRECTION_OUTPUT stream to implement audio or video recording. * * \subsection ssec_stream_target Stream target * * To make the newly connected stream automatically connect to an existing * PipeWire node, use the \ref PW_STREAM_FLAG_AUTOCONNECT and set the * PW_KEY_OBJECT_SERIAL or the PW_KEY_NODE_NAME value of the target node * in the PW_KEY_TARGET_OBJECT property before connecting. * * \subsection ssec_stream_formats Stream formats * * An array of possible formats that this stream can consume or provide * must be specified. * * \section sec_format Format negotiation * * After connecting the stream, the server will want to configure some * parameters on the stream. You will be notified of these changes * with the param_changed event. * * When a format param change is emitted, the client should now prepare * itself to deal with the format and complete the negotiation procedure * with a call to \ref pw_stream_update_params(). * * As arguments to \ref pw_stream_update_params() an array of spa_param * structures must be given. They contain parameters such as buffer size, * number of buffers, required metadata and other parameters for the * media buffers. * * \section sec_buffers Buffer negotiation * * After completing the format negotiation, PipeWire will allocate and * notify the stream of the buffers that will be used to exchange data * between client and server. * * With the add_buffer event, a stream will be notified of a new buffer * that can be used for data transport. You can attach user_data to these * buffers. The buffers can only be used with the stream that emitted * the add_buffer event. * * After the buffers are negotiated, the stream will transition to the * \ref PW_STREAM_STATE_PAUSED state. * * \section sec_streaming Streaming * * From the \ref PW_STREAM_STATE_PAUSED state, the stream can be set to * the \ref PW_STREAM_STATE_STREAMING state by the PipeWire server when * data transport is started. * * Depending on how the stream was connected it will need to Produce or * Consume data for/from PipeWire as explained in the following * subsections. * * \subsection ssec_consume Consume data * * The process event is emitted for each new buffer that can be * consumed. * * \ref pw_stream_dequeue_buffer() should be used to get the data and * metadata of the buffer. * * The buffer is owned by the stream and stays alive until the * remove_buffer callback has returned or the stream is destroyed. * * When the buffer has been processed, call \ref pw_stream_queue_buffer() * to let PipeWire reuse the buffer. * * Although not strictly required, it is recommended to call \ref * pw_stream_dequeue_buffer() and pw_stream_queue_buffer() from the * process() callback to minimize the amount of buffering and * maximize the amount of buffer reuse in the stream. * * It is also possible to dequeue the buffer from the process event, * then process and queue the buffer from a helper thread. It is also * possible to dequeue, process and queue a buffer from a helper thread * after receiving the process event. * * \subsection ssec_produce Produce data * * The process event is emitted when a new buffer should be queued. * * When the PW_STREAM_FLAG_RT_PROCESS flag was given, this function will be * called from a realtime thread and it is not safe to call non-reatime * functions such as doing file operations, blocking operations or any of * the PipeWire functions that are not explicitly marked as being RT safe. * * \ref pw_stream_dequeue_buffer() gives an empty buffer that can be filled. * * The buffer is owned by the stream and stays alive until the * remove_buffer event is emitted or the stream is destroyed. * * Filled buffers should be queued with \ref pw_stream_queue_buffer(). * * Although not strictly required, it is recommended to call \ref * pw_stream_dequeue_buffer() and pw_stream_queue_buffer() from the * process() callback to minimize the amount of buffering and * maximize the amount of buffer reuse in the stream. * * Buffers that are queued after the process event completes will be delayed * to the next processing cycle. * * \section sec_stream_driving Driving the graph * * Starting in 0.3.34, it is possible for a stream to drive the graph. * This allows interrupt-driven scheduling for drivers implemented as * PipeWire streams, without having to reimplement the stream as a SPA * plugin. * * A stream cannot drive the graph unless it is in the * \ref PW_STREAM_STATE_STREAMING state and \ref pw_stream_is_driving() returns * true. It must then use pw_stream_trigger_process() to start the graph * cycle. * * \ref pw_stream_trigger_process() will result in a process event, where a buffer * should be dequeued, and queued again. This is the recommended behaviour that * minimizes buffering and maximized buffer reuse. * * Producers of data that drive the graph can also dequeue a buffer in a helper * thread, fill it with data and then call \ref pw_stream_trigger_process() to * start the graph cycle. In the process event they will then queue the filled * buffer and dequeue a new empty buffer to fill again in the helper thread, * * Consumers of data that drive the graph (pull based scheduling) will use * \ref pw_stream_trigger_process() to start the graph and will dequeue, process * and queue the buffers in the process event. * * \section sec_stream_process_requests Request processing * * A stream that is not driving the graph can request a new graph cycle by doing * \ref pw_stream_trigger_process(). This will result in a RequestProcess command * in the driver stream. If the driver supports this, it can then perform * \ref pw_stream_trigger_process() to start the actual graph cycle. * * \section sec_stream_disconnect Disconnect * * Use \ref pw_stream_disconnect() to disconnect a stream after use. * * \section sec_stream_configuration Configuration * * \subsection ssec_config_properties Stream Properties * * \subsection ssec_config_rules Stream Rules * * \section sec_stream_environment Environment Variables * * The environment variable PIPEWIRE_AUTOCONNECT can be used to override the * flag and force apps to autoconnect or not. * */ /** \defgroup pw_stream Stream * * \brief PipeWire stream objects * * The stream object provides a convenient way to send and * receive data streams from/to PipeWire. * * \see \ref page_streams, \ref api_pw_core */ /** * \addtogroup pw_stream * \{ */ struct pw_stream; #include #include #include #include /** \enum pw_stream_state The state of a stream */ enum pw_stream_state { PW_STREAM_STATE_ERROR = -1, /**< the stream is in error */ PW_STREAM_STATE_UNCONNECTED = 0, /**< unconnected */ PW_STREAM_STATE_CONNECTING = 1, /**< connection is in progress */ PW_STREAM_STATE_PAUSED = 2, /**< paused */ PW_STREAM_STATE_STREAMING = 3 /**< streaming */ }; /** a buffer structure obtained from pw_stream_dequeue_buffer(). The size of this * structure can grow as more fields are added in the future */ struct pw_buffer { struct spa_buffer *buffer; /**< the spa buffer */ void *user_data; /**< user data attached to the buffer. The user of * the stream can set custom data associated with the * buffer, typically in the add_buffer event. Any * cleanup should be performed in the remove_buffer * event. The user data is returned unmodified each * time a buffer is dequeued. */ uint64_t size; /**< This field is set by the user and the sum of * all queued buffers is returned in the time info. * For audio, it is advised to use the number of * frames in the buffer for this field. */ uint64_t requested; /**< For playback streams, this field contains the * suggested amount of data to provide. For audio * streams this will be the amount of frames * required by the resampler. This field is 0 * when no suggestion is provided. Since 0.3.49 */ uint64_t time; /**< For capture streams, this field contains the * cycle time in nanoseconds when this buffer was * queued in the stream. It can be compared against * the pw_time values or pw_stream_get_nsec() * Since 1.0.5 */ }; struct pw_stream_control { const char *name; /**< name of the control */ uint32_t flags; /**< extra flags (unused) */ float def; /**< default value */ float min; /**< min value */ float max; /**< max value */ float *values; /**< array of values */ uint32_t n_values; /**< number of values in array */ uint32_t max_values; /**< max values that can be set on this control */ }; /** A time structure. * * Use pw_stream_get_time_n() to get an updated time snapshot of the stream. * The time snapshot can give information about the time in the driver of the * graph, the delay to the edge of the graph and the internal queuing in the * stream. * * pw_time.ticks gives a monotonic increasing counter of the time in the graph * driver. I can be used to generate a timetime to schedule samples as well * as detect discontinuities in the timeline caused by xruns. * * pw_time.delay is expressed as pw_time.rate, the time domain of the graph. This * value, and pw_time.ticks, were captured at pw_time.now and can be extrapolated * to the current time like this: * *\code{.c} * uint64_t now = pw_stream_get_nsec(stream); * int64_t diff = now - pw_time.now; * int64_t elapsed = (pw_time.rate.denom * diff) / (pw_time.rate.num * SPA_NSEC_PER_SEC); *\endcode * * pw_time.delay contains the total delay that a signal will travel through the * graph. This includes the delay caused by filters in the graph as well as delays * caused by the hardware. The delay is usually quite stable and should only change when * the topology, quantum or samplerate of the graph changes. * * The delay requires the application to send the stream early relative to other synchronized * streams in order to arrive at the edge of the graph in time. This is usually done by * delaying the other streams with the given delay. * * Note that the delay can be negative. A negative delay means that this stream should be * delayed with the (positive) delay relative to other streams. * * pw_time.queued and pw_time.buffered is expressed in the time domain of the stream, * or the format that is used for the buffers of this stream. * * pw_time.queued is the sum of all the pw_buffer.size fields of the buffers that are * currently queued in the stream but not yet processed. The application can choose * the units of this value, for example, time, samples, frames or bytes (below * expressed as app.rate). * * pw_time.buffered is format dependent, for audio/raw it contains the number of frames * that are buffered inside the resampler/converter. * * The total delay of data in a stream is the sum of the queued and buffered data * (not yet processed data) and the delay to the edge of the graph, usually a * playback or capture device. * * For an audio playback stream, if you were to queue a buffer, the total delay * in milliseconds for the first sample in the newly queued buffer to be played * by the hardware can be calculated as: * *\code{.unparsed} * (pw_time.buffered * 1000 / stream.samplerate) + * (pw_time.queued * 1000 / app.rate) + * ((pw_time.delay - elapsed) * 1000 * pw_time.rate.num / pw_time.rate.denom) *\endcode * * The current extrapolated time (in ms) in the source or sink can be calculated as: * *\code{.unparsed} * (pw_time.ticks + elapsed) * 1000 * pw_time.rate.num / pw_time.rate.denom *\endcode * * Below is an overview of the different timing values: * *\code{.unparsed} * stream time domain graph time domain * /-----------------------\/-----------------------------\ * * queue +-+ +-+ +-----------+ +--------+ * ----> | | | |->| converter | -> graph -> | kernel | -> speaker * <---- +-+ +-+ +-----------+ +--------+ * dequeue buffers \-------------------/\--------/ * graph internal * latency latency * \--------/\-------------/\-----------------------------/ * queued buffered delay *\endcode */ struct pw_time { int64_t now; /**< the time in nanoseconds. This is the time when this * time report was updated. It is usually updated every * graph cycle. You can use pw_stream_get_nsec() to * calculate the elapsed time between this report and * the current time and calculate updated ticks and delay * values. */ struct spa_fraction rate; /**< the rate of \a ticks and delay. This is usually * expressed in 1/. */ uint64_t ticks; /**< the ticks at \a now. This is the current time that * the remote end is reading/writing. This is monotonicaly * increasing. */ int64_t delay; /**< delay to device. This is the time it will take for * the next output sample of the stream to be presented by * the playback device or the time a sample traveled * from the capture device. This delay includes the * delay introduced by all filters on the path between * the stream and the device. The delay is normally * constant in a graph and can change when the topology * of the graph or the quantum changes. This delay does * not include the delay caused by queued buffers. */ uint64_t queued; /**< data queued in the stream, this is the sum * of the size fields in the pw_buffer that are * currently queued */ uint64_t buffered; /**< for audio/raw streams, this contains the extra * number of frames buffered in the resampler. * Since 0.3.50. */ uint32_t queued_buffers; /**< the number of buffers that are queued. Since 0.3.50 */ uint32_t avail_buffers; /**< the number of buffers that can be dequeued. Since 0.3.50 */ uint64_t size; /**< for audio/raw playback streams, this contains the number of * samples requested by the resampler for the current * quantum. for audio/raw capture streams this will be the number * of samples available for the current quantum. Since 1.1.0 */ }; #include /** Events for a stream. These events are always called from the mainloop * unless explicitly documented otherwise. */ struct pw_stream_events { #define PW_VERSION_STREAM_EVENTS 2 uint32_t version; void (*destroy) (void *data); /** when the stream state changes */ void (*state_changed) (void *data, enum pw_stream_state old, enum pw_stream_state state, const char *error); /** Notify information about a control. */ void (*control_info) (void *data, uint32_t id, const struct pw_stream_control *control); /** when io changed on the stream. */ void (*io_changed) (void *data, uint32_t id, void *area, uint32_t size); /** when a parameter changed */ void (*param_changed) (void *data, uint32_t id, const struct spa_pod *param); /** when a new buffer was created for this stream */ void (*add_buffer) (void *data, struct pw_buffer *buffer); /** when a buffer was destroyed for this stream */ void (*remove_buffer) (void *data, struct pw_buffer *buffer); /** when a buffer can be queued (for playback streams) or * dequeued (for capture streams). This is normally called from the * mainloop but can also be called directly from the realtime data * thread if the user is prepared to deal with this. */ void (*process) (void *data); /** The stream is drained */ void (*drained) (void *data); /** A command notify, Since 0.3.39:1 */ void (*command) (void *data, const struct spa_command *command); /** a trigger_process completed. Since version 0.3.40:2. * This is normally called from the mainloop but since 1.1.0 it * can also be called directly from the realtime data * thread if the user is prepared to deal with this. */ void (*trigger_done) (void *data); }; /** Convert a stream state to a readable string */ const char * pw_stream_state_as_string(enum pw_stream_state state); /** \enum pw_stream_flags Extra flags that can be used in \ref pw_stream_connect() */ enum pw_stream_flags { PW_STREAM_FLAG_NONE = 0, /**< no flags */ PW_STREAM_FLAG_AUTOCONNECT = (1 << 0), /**< try to automatically connect * this stream */ PW_STREAM_FLAG_INACTIVE = (1 << 1), /**< start the stream inactive, * pw_stream_set_active() needs to be * called explicitly */ PW_STREAM_FLAG_MAP_BUFFERS = (1 << 2), /**< mmap the buffers except DmaBuf that is not * explicitly marked as mappable. */ PW_STREAM_FLAG_DRIVER = (1 << 3), /**< be a driver */ PW_STREAM_FLAG_RT_PROCESS = (1 << 4), /**< call process from the realtime * thread. You MUST use RT safe functions * in the process callback. */ PW_STREAM_FLAG_NO_CONVERT = (1 << 5), /**< don't convert format */ PW_STREAM_FLAG_EXCLUSIVE = (1 << 6), /**< require exclusive access to the * device */ PW_STREAM_FLAG_DONT_RECONNECT = (1 << 7), /**< don't try to reconnect this stream * when the sink/source is removed */ PW_STREAM_FLAG_ALLOC_BUFFERS = (1 << 8), /**< the application will allocate buffer * memory. In the add_buffer event, the * data of the buffer should be set */ PW_STREAM_FLAG_TRIGGER = (1 << 9), /**< the output stream will not be scheduled * automatically but _trigger_process() * needs to be called. This can be used * when the output of the stream depends * on input from other streams. */ PW_STREAM_FLAG_ASYNC = (1 << 10), /**< Buffers will not be dequeued/queued from * the realtime process() function. This is * assumed when RT_PROCESS is unset but can * also be the case when the process() function * does a trigger_process() that will then * dequeue/queue a buffer from another process() * function. since 0.3.73 */ PW_STREAM_FLAG_EARLY_PROCESS = (1 << 11), /**< Call process as soon as there is a buffer * to dequeue. This is only relevant for * playback and when not using RT_PROCESS. It * can be used to keep the maximum number of * buffers queued. Since 0.3.81 */ PW_STREAM_FLAG_RT_TRIGGER_DONE = (1 << 12), /**< Call trigger_done from the realtime * thread. You MUST use RT safe functions * in the trigger_done callback. Since 1.1.0 */ }; /** Create a new unconnected \ref pw_stream * \return a newly allocated \ref pw_stream */ struct pw_stream * pw_stream_new(struct pw_core *core, /**< a \ref pw_core */ const char *name, /**< a stream media name */ struct pw_properties *props /**< stream properties, ownership is taken */); struct pw_stream * pw_stream_new_simple(struct pw_loop *loop, /**< a \ref pw_loop to use as the main loop */ const char *name, /**< a stream media name */ struct pw_properties *props,/**< stream properties, ownership is taken */ const struct pw_stream_events *events, /**< stream events */ void *data /**< data passed to events */); /** Destroy a stream */ void pw_stream_destroy(struct pw_stream *stream); void pw_stream_add_listener(struct pw_stream *stream, struct spa_hook *listener, const struct pw_stream_events *events, void *data); enum pw_stream_state pw_stream_get_state(struct pw_stream *stream, const char **error); const char *pw_stream_get_name(struct pw_stream *stream); struct pw_core *pw_stream_get_core(struct pw_stream *stream); const struct pw_properties *pw_stream_get_properties(struct pw_stream *stream); int pw_stream_update_properties(struct pw_stream *stream, const struct spa_dict *dict); /** Connect a stream for input or output on \a port_path. * \return 0 on success < 0 on error. * * You should connect to the process event and use pw_stream_dequeue_buffer() * to get the latest metadata and data. */ int pw_stream_connect(struct pw_stream *stream, /**< a \ref pw_stream */ enum pw_direction direction, /**< the stream direction */ uint32_t target_id, /**< should have the value PW_ID_ANY. * To select a specific target * node, specify the * PW_KEY_OBJECT_SERIAL or the * PW_KEY_NODE_NAME value of the target * node in the PW_KEY_TARGET_OBJECT * property of the stream. * Specifying target nodes by * their id is deprecated. */ enum pw_stream_flags flags, /**< stream flags */ const struct spa_pod **params, /**< an array with params. The params * should ideally contain supported * formats. */ uint32_t n_params /**< number of items in \a params */); /** Get the node ID of the stream. * \return node ID. */ uint32_t pw_stream_get_node_id(struct pw_stream *stream); /** Disconnect \a stream */ int pw_stream_disconnect(struct pw_stream *stream); /** Set the stream in error state */ int pw_stream_set_error(struct pw_stream *stream, /**< a \ref pw_stream */ int res, /**< a result code */ const char *error, /**< an error message */ ...) SPA_PRINTF_FUNC(3, 4); /** Update the param exposed on the stream. */ int pw_stream_update_params(struct pw_stream *stream, /**< a \ref pw_stream */ const struct spa_pod **params, /**< an array of params. */ uint32_t n_params /**< number of elements in \a params */); /** * Set a parameter on the stream. This is like pw_stream_set_control() but with * a complete spa_pod param. It can also be called from the param_changed event handler * to intercept and modify the param for the adapter. Since 0.3.70 */ int pw_stream_set_param(struct pw_stream *stream, /**< a \ref pw_stream */ uint32_t id, /**< the id of the param */ const struct spa_pod *param /**< the params to set */); /** Get control values */ const struct pw_stream_control *pw_stream_get_control(struct pw_stream *stream, uint32_t id); /** Set control values */ int pw_stream_set_control(struct pw_stream *stream, uint32_t id, uint32_t n_values, float *values, ...); /** Query the time on the stream, RT safe */ int pw_stream_get_time_n(struct pw_stream *stream, struct pw_time *time, size_t size); /** Get the current time in nanoseconds. This value can be compared with * the \ref pw_time.now value. RT safe. Since 1.1.0 */ uint64_t pw_stream_get_nsec(struct pw_stream *stream); /** Get the data loop that is doing the processing of this stream. This loop * is assigned after pw_stream_connect(). * Since 1.1.0 */ struct pw_loop *pw_stream_get_data_loop(struct pw_stream *stream); /** Query the time on the stream, deprecated since 0.3.50, * use pw_stream_get_time_n() to get the fields added since 0.3.50. RT safe. */ SPA_DEPRECATED int pw_stream_get_time(struct pw_stream *stream, struct pw_time *time); /** Get a buffer that can be filled for playback streams or consumed * for capture streams. RT safe. */ struct pw_buffer *pw_stream_dequeue_buffer(struct pw_stream *stream); /** Submit a buffer for playback or recycle a buffer for capture. RT safe. */ int pw_stream_queue_buffer(struct pw_stream *stream, struct pw_buffer *buffer); /** Return a buffer to the queue without using it. This makes the buffer * immediately available to dequeue again. RT safe. */ int pw_stream_return_buffer(struct pw_stream *stream, struct pw_buffer *buffer); /** Activate or deactivate the stream */ int pw_stream_set_active(struct pw_stream *stream, bool active); /** Flush a stream. When \a drain is true, the drained callback will * be called when all data is played or recorded. The stream can be resumed * after the drain by setting it active again with * \ref pw_stream_set_active(). A flush without a drain is mostly useful afer * a state change to PAUSED, to flush any remaining data from the queues and * the converters. RT safe. */ int pw_stream_flush(struct pw_stream *stream, bool drain); /** Check if the stream is driving. The stream needs to have the * PW_STREAM_FLAG_DRIVER set. When the stream is driving, * pw_stream_trigger_process() needs to be called when data is * available (output) or needed (input). Since 0.3.34 */ bool pw_stream_is_driving(struct pw_stream *stream); /** Check if the graph is using lazy scheduling. If the stream is * driving according to \ref pw_stream_is_driving(), then it should * consider taking into account the RequestProcess commands when * driving the graph. * * If the stream is not driving, it should send out RequestProcess * events with \ref pw_stream_emit_event() or indirectly with * \ref pw_stream_trigger_process() to suggest a new graph cycle * to the driver. * * It is not a requirement that all RequestProcess events/commands * need to start a graph cycle. * Since 1.4.0 */ bool pw_stream_is_lazy(struct pw_stream *stream); /** Trigger a push/pull on the stream. One iteration of the graph will * be scheduled when the stream is driving according to * \ref pw_stream_is_driving(). If it successfully finishes, process() * will be called and the trigger_done event will be emitted. It is * possible for the graph iteration to not finish, so * pw_stream_trigger_process() needs to be called again even if process() * and trigger_done is not called. * * If there is a deadline after which the stream will have xrun, * pw_stream_trigger_process() should be called then, whether or not * process()/trigger_done has been called. Sound hardware will xrun if * there is any delay in audio processing, so the ALSA plugin triggers the * graph every quantum to ensure audio keeps flowing. Drivers that * do not have a deadline, such as the freewheel driver, should * use a timeout to ensure that forward progress keeps being made. * A reasonable choice of deadline is three times the quantum: if * the graph is taking 3x longer than normal, it is likely that it * is hung and should be retriggered. * * Streams that are not drivers according to \ref pw_stream_is_driving() * can also call this method. The result is that a RequestProcess event * is sent to the driver. If the graph is lazy scheduling according to * \ref pw_stream_is_lazy(), this might result in a graph cycle by the * driver. If the graph is not lazy scheduling and the stream is not a * driver, this method will have no effect. * * RT safe. * * Since 0.3.34 */ int pw_stream_trigger_process(struct pw_stream *stream); /** Emit an event from this stream. RT safe. * Since 1.2.6 */ int pw_stream_emit_event(struct pw_stream *stream, const struct spa_event *event); /** Adjust the rate of the stream. * When the stream is using an adaptive resampler, adjust the resampler rate. * When there is no resampler, -ENOTSUP is returned. Activating the adaptive * resampler will add a small amount of delay to the samples, you can deactivate * it again by setting a value <= 0.0. RT safe. * Since 1.4.0 */ int pw_stream_set_rate(struct pw_stream *stream, double rate); /** * \} */ #ifdef __cplusplus } #endif #endif /* PIPEWIRE_STREAM_H */