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path: root/src/pulse/stream.h
 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449  #ifndef foostreamhfoo #define foostreamhfoo /* $Id$ */ /*** This file is part of PulseAudio. PulseAudio is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. PulseAudio is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with PulseAudio; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. ***/ #include #include #include #include #include #include #include /** \page streams Audio Streams * * \section overv_sec Overview * * Audio streams form the central functionality of the sound server. Data is * routed, converted and mixed from several sources before it is passed along * to a final output. Currently, there are three forms of audio streams: * * \li Playback streams - Data flows from the client to the server. * \li Record streams - Data flows from the server to the client. * \li Upload streams - Similar to playback streams, but the data is stored in * the sample cache. See \ref scache for more information * about controlling the sample cache. * * \section create_sec Creating * * To access a stream, a pa_stream object must be created using * pa_stream_new(). At this point the audio sample format and mapping of * channels must be specified. See \ref sample and \ref channelmap for more * information about those structures. * * This first step will only create a client-side object, representing the * stream. To use the stream, a server-side object must be created and * associated with the local object. Depending on which type of stream is * desired, a different function is needed: * * \li Playback stream - pa_stream_connect_playback() * \li Record stream - pa_stream_connect_record() * \li Upload stream - pa_stream_connect_upload() (see \ref scache) * * Similar to how connections are done in contexts, connecting a stream will * not generate a pa_operation object. Also like contexts, the application * should register a state change callback, using * pa_stream_set_state_callback(), and wait for the stream to enter an active * state. * * \subsection bufattr_subsec Buffer Attributes * * Playback and record streams always have a server side buffer as * part of the data flow. The size of this buffer strikes a * compromise between low latency and sensitivity for buffer * overflows/underruns. * * The buffer metrics may be controlled by the application. They are * described with a pa_buffer_attr structure which contains a number * of fields: * * \li maxlength - The absolute maximum number of bytes that can be stored in * the buffer. If this value is exceeded then data will be * lost. * \li tlength - The target length of a playback buffer. The server will only * send requests for more data as long as the buffer has less * than this number of bytes of data. * \li prebuf - Number of bytes that need to be in the buffer before * playback will commence. Start of playback can be forced using * pa_stream_trigger() even though the prebuffer size hasn't been * reached. If a buffer underrun occurs, this prebuffering will be * again enabled. If the playback shall never stop in case of a buffer * underrun, this value should be set to 0. In that case the read * index of the output buffer overtakes the write index, and hence the * fill level of the buffer is negative. * \li minreq - Minimum free number of the bytes in the playback buffer before * the server will request more data. * \li fragsize - Maximum number of bytes that the server will push in one * chunk for record streams. * * The server side playback buffers are indexed by a write and a read * index. The application writes to the write index and the sound * device reads from the read index. The read index is increased * monotonically, while the write index may be freely controlled by * the application. Substracting the read index from the write index * will give you the current fill level of the buffer. The read/write * indexes are 64bit values and measured in bytes, they will never * wrap. The current read/write index may be queried using * pa_stream_get_timing_info() (see below for more information). In * case of a buffer underrun the read index is equal or larger than * the write index. Unless the prebuf value is 0, PulseAudio will * temporarily pause playback in such a case, and wait until the * buffer is filled up to prebuf bytes again. If prebuf is 0, the * read index may be larger than the write index, in which case * silence is played. If the application writes data to indexes lower * than the read index, the data is immediately lost. * * \section transfer_sec Transferring Data * * Once the stream is up, data can start flowing between the client and the * server. Two different access models can be used to transfer the data: * * \li Asynchronous - The application register a callback using * pa_stream_set_write_callback() and * pa_stream_set_read_callback() to receive notifications * that data can either be written or read. * \li Polled - Query the library for available data/space using * pa_stream_writable_size() and pa_stream_readable_size() and * transfer data as needed. The sizes are stored locally, in the * client end, so there is no delay when reading them. * * It is also possible to mix the two models freely. * * Once there is data/space available, it can be transferred using either * pa_stream_write() for playback, or pa_stream_peek() / pa_stream_drop() for * record. Make sure you do not overflow the playback buffers as data will be * dropped. * * \section bufctl_sec Buffer Control * * The transfer buffers can be controlled through a number of operations: * * \li pa_stream_cork() - Start or stop the playback or recording. * \li pa_stream_trigger() - Start playback immediatly and do not wait for * the buffer to fill up to the set trigger level. * \li pa_stream_prebuf() - Reenable the playback trigger level. * \li pa_stream_drain() - Wait for the playback buffer to go empty. Will * return a pa_operation object that will indicate when * the buffer is completely drained. * \li pa_stream_flush() - Drop all data from the playback buffer and do not * wait for it to finish playing. * * \section seek_modes Seeking in the Playback Buffer * * A client application may freely seek in the playback buffer. To * accomplish that the pa_stream_write() function takes a seek mode * and an offset argument. The seek mode is one of: * * \li PA_SEEK_RELATIVE - seek relative to the current write index * \li PA_SEEK_ABSOLUTE - seek relative to the beginning of the playback buffer, (i.e. the first that was ever played in the stream) * \li PA_SEEK_RELATIVE_ON_READ - seek relative to the current read index. Use this to write data to the output buffer that should be played as soon as possible * \li PA_SEEK_RELATIVE_END - seek relative to the last byte ever written. * * If an application just wants to append some data to the output * buffer, PA_SEEK_RELATIVE and an offset of 0 should be used. * * After a call to pa_stream_write() the write index will be left at * the position right after the last byte of the written data. * * \section latency_sec Latency * * A major problem with networked audio is the increased latency caused by * the network. To remedy this, PulseAudio supports an advanced system of * monitoring the current latency. * * To get the raw data needed to calculate latencies, call * pa_stream_get_timing_info(). This will give you a pa_timing_info * structure that contains everything that is known about the server * side buffer transport delays and the backend active in the * server. (Besides other things it contains the write and read index * values mentioned above.) * * This structure is updated every time a * pa_stream_update_timing_info() operation is executed. (i.e. before * the first call to this function the timing information structure is * not available!) Since it is a lot of work to keep this structure * up-to-date manually, PulseAudio can do that automatically for you: * if PA_STREAM_AUTO_TIMING_UPDATE is passed when connecting the * stream PulseAudio will automatically update the structure every * 100ms and every time a function is called that might invalidate the * previously known timing data (such as pa_stream_write() or * pa_stream_flush()). Please note however, that there always is a * short time window when the data in the timing information structure * is out-of-date. PulseAudio tries to mark these situations by * setting the write_index_corrupt and read_index_corrupt fields * accordingly. * * The raw timing data in the pa_timing_info structure is usually hard * to deal with. Therefore a more simplistic interface is available: * you can call pa_stream_get_time() or pa_stream_get_latency(). The * former will return the current playback time of the hardware since * the stream has been started. The latter returns the time a sample * that you write now takes to be played by the hardware. These two * functions base their calculations on the same data that is returned * by pa_stream_get_timing_info(). Hence the same rules for keeping * the timing data up-to-date apply here. In case the write or read * index is corrupted, these two functions will fail with * PA_ERR_NODATA set. * * Since updating the timing info structure usually requires a full * network round trip and some applications monitor the timing very * often PulseAudio offers a timing interpolation system. If * PA_STREAM_INTERPOLATE_TIMING is passed when connecting the stream, * pa_stream_get_time() and pa_stream_get_latency() will try to * interpolate the current playback time/latency by estimating the * number of samples that have been played back by the hardware since * the last regular timing update. It is espcially useful to combine * this option with PA_STREAM_AUTO_TIMING_UPDATE, which will enable * you to monitor the current playback time/latency very precisely and * very frequently without requiring a network round trip every time. * * \section flow_sec Overflow and underflow * * Even with the best precautions, buffers will sometime over - or * underflow. To handle this gracefully, the application can be * notified when this happens. Callbacks are registered using * pa_stream_set_overflow_callback() and * pa_stream_set_underflow_callback(). * * \section sync_streams Sychronizing Multiple Playback Streams * * PulseAudio allows applications to fully synchronize multiple * playback streams that are connected to the same output device. That * means the streams will always be played back sample-by-sample * synchronously. If stream operations like pa_stream_cork() are * issued on one of the synchronized streams, they are simultaneously * issued on the others. * * To synchronize a stream to another, just pass the "master" stream * as last argument to pa_stream_connect_playack(). To make sure that * the freshly created stream doesn't start playback right-away, make * sure to pass PA_STREAM_START_CORKED and - after all streams have * been created - uncork them all with a single call to * pa_stream_cork() for the master stream. * * To make sure that a particular stream doesn't stop to play when a * server side buffer underrun happens on it while the other * synchronized streams continue playing and hence deviate you need to * pass a "prebuf" pa_buffer_attr of 0 when connecting it. * * \section disc_sec Disconnecting * * When a stream has served is purpose it must be disconnected with * pa_stream_disconnect(). If you only unreference it, then it will live on * and eat resources both locally and on the server until you disconnect the * context. * */ /** \file * Audio streams for input, output and sample upload */ PA_C_DECL_BEGIN /** An opaque stream for playback or recording */ typedef struct pa_stream pa_stream; /** A generic callback for operation completion */ typedef void (*pa_stream_success_cb_t) (pa_stream*s, int success, void *userdata); /** A generic request callback */ typedef void (*pa_stream_request_cb_t)(pa_stream *p, size_t length, void *userdata); /** A generic notification callback */ typedef void (*pa_stream_notify_cb_t)(pa_stream *p, void *userdata); /** Create a new, unconnected stream with the specified name and sample type */ pa_stream* pa_stream_new( pa_context *c /**< The context to create this stream in */, const char *name /**< A name for this stream */, const pa_sample_spec *ss /**< The desired sample format */, const pa_channel_map *map /**< The desired channel map, or NULL for default */); /** Decrease the reference counter by one */ void pa_stream_unref(pa_stream *s); /** Increase the reference counter by one */ pa_stream *pa_stream_ref(pa_stream *s); /** Return the current state of the stream */ pa_stream_state_t pa_stream_get_state(pa_stream *p); /** Return the context this stream is attached to */ pa_context* pa_stream_get_context(pa_stream *p); /** Return the device (sink input or source output) index this stream is connected to */ uint32_t pa_stream_get_index(pa_stream *s); /** Connect the stream to a sink */ int pa_stream_connect_playback( pa_stream *s /**< The stream to connect to a sink */, const char *dev /**< Name of the sink to connect to, or NULL for default */ , const pa_buffer_attr *attr /**< Buffering attributes, or NULL for default */, pa_stream_flags_t flags /**< Additional flags, or 0 for default */, pa_cvolume *volume /**< Initial volume, or NULL for default */, pa_stream *sync_stream /**< Synchronize this stream with the specified one, or NULL for a standalone stream*/); /** Connect the stream to a source */ int pa_stream_connect_record( pa_stream *s /**< The stream to connect to a source */ , const char *dev /**< Name of the source to connect to, or NULL for default */, const pa_buffer_attr *attr /**< Buffer attributes, or NULL for default */, pa_stream_flags_t flags /**< Additional flags, or 0 for default */); /** Disconnect a stream from a source/sink */ int pa_stream_disconnect(pa_stream *s); /** Write some data to the server (for playback sinks), if free_cb is * non-NULL this routine is called when all data has been written out * and an internal reference to the specified data is kept, the data * is not copied. If NULL, the data is copied into an internal * buffer. The client my freely seek around in the output buffer. For * most applications passing 0 and PA_SEEK_RELATIVE as arguments for * offset and seek should be useful.*/ int pa_stream_write( pa_stream *p /**< The stream to use */, const void *data /**< The data to write */, size_t length /**< The length of the data to write */, pa_free_cb_t free_cb /**< A cleanup routine for the data or NULL to request an internal copy */, int64_t offset, /**< Offset for seeking, must be 0 for upload streams */ pa_seek_mode_t seek /**< Seek mode, must be PA_SEEK_RELATIVE for upload streams */); /** Read the next fragment from the buffer (for recording). * data will point to the actual data and length will contain the size * of the data in bytes (which can be less than a complete framgnet). * Use pa_stream_drop() to actually remove the data from the * buffer. If no data is available will return a NULL pointer \since 0.8 */ int pa_stream_peek( pa_stream *p /**< The stream to use */, const void **data /**< Pointer to pointer that will point to data */, size_t *length /**< The length of the data read */); /** Remove the current fragment on record streams. It is invalid to do this without first * calling pa_stream_peek(). \since 0.8 */ int pa_stream_drop(pa_stream *p); /** Return the nember of bytes that may be written using pa_stream_write() */ size_t pa_stream_writable_size(pa_stream *p); /** Return the number of bytes that may be read using pa_stream_read() \since 0.8 */ size_t pa_stream_readable_size(pa_stream *p); /** Drain a playback stream. Use this for notification when the buffer is empty */ pa_operation* pa_stream_drain(pa_stream *s, pa_stream_success_cb_t cb, void *userdata); /** Request a timing info structure update for a stream. Use * pa_stream_get_timing_info() to get access to the raw timing data, * or pa_stream_get_time() or pa_stream_get_latency() to get cleaned * up values. */ pa_operation* pa_stream_update_timing_info(pa_stream *p, pa_stream_success_cb_t cb, void *userdata); /** Set the callback function that is called whenever the state of the stream changes */ void pa_stream_set_state_callback(pa_stream *s, pa_stream_notify_cb_t cb, void *userdata); /** Set the callback function that is called when new data may be * written to the stream. */ void pa_stream_set_write_callback(pa_stream *p, pa_stream_request_cb_t cb, void *userdata); /** Set the callback function that is called when new data is available from the stream. * Return the number of bytes read. \since 0.8 */ void pa_stream_set_read_callback(pa_stream *p, pa_stream_request_cb_t cb, void *userdata); /** Set the callback function that is called when a buffer overflow happens. (Only for playback streams) \since 0.8 */ void pa_stream_set_overflow_callback(pa_stream *p, pa_stream_notify_cb_t cb, void *userdata); /** Set the callback function that is called when a buffer underflow happens. (Only for playback streams) \since 0.8 */ void pa_stream_set_underflow_callback(pa_stream *p, pa_stream_notify_cb_t cb, void *userdata); /** Set the callback function that is called whenever a latency information update happens. Useful on PA_STREAM_AUTO_TIMING_UPDATE streams only. (Only for playback streams) \since 0.8.2 */ void pa_stream_set_latency_update_callback(pa_stream *p, pa_stream_notify_cb_t cb, void *userdata); /** Pause (or resume) playback of this stream temporarily. Available on both playback and recording streams. \since 0.3 */ pa_operation* pa_stream_cork(pa_stream *s, int b, pa_stream_success_cb_t cb, void *userdata); /** Flush the playback buffer of this stream. Most of the time you're * better off using the parameter delta of pa_stream_write() instead of this * function. Available on both playback and recording streams. \since 0.3 */ pa_operation* pa_stream_flush(pa_stream *s, pa_stream_success_cb_t cb, void *userdata); /** Reenable prebuffering as specified in the pa_buffer_attr * structure. Available for playback streams only. \since 0.6 */ pa_operation* pa_stream_prebuf(pa_stream *s, pa_stream_success_cb_t cb, void *userdata); /** Request immediate start of playback on this stream. This disables * prebuffering as specified in the pa_buffer_attr * structure, temporarily. Available for playback streams only. \since 0.3 */ pa_operation* pa_stream_trigger(pa_stream *s, pa_stream_success_cb_t cb, void *userdata); /** Rename the stream. \since 0.5 */ pa_operation* pa_stream_set_name(pa_stream *s, const char *name, pa_stream_success_cb_t cb, void *userdata); /** Return the current playback/recording time. This is based on the * data in the timing info structure returned by * pa_stream_get_timing_info(). This function will usually only return * new data if a timing info update has been recieved. Only if timing * interpolation has been requested (PA_STREAM_INTERPOLATE_TIMING) * the data from the last timing update is used for an estimation of * the current playback/recording time based on the local time that * passed since the timing info structure has been acquired. The time * value returned by this function is guaranteed to increase * monotonically. (that means: the returned value is always greater or * equal to the value returned on the last call) This behaviour can * be disabled by using PA_STREAM_NOT_MONOTONOUS. This may be * desirable to deal better with bad estimations of transport * latencies, but may have strange effects if the application is not * able to deal with time going 'backwards'. \since 0.6 */ int pa_stream_get_time(pa_stream *s, pa_usec_t *r_usec); /** Return the total stream latency. This function is based on * pa_stream_get_time(). In case the stream is a monitoring stream the * result can be negative, i.e. the captured samples are not yet * played. In this case *negative is set to 1. \since 0.6 */ int pa_stream_get_latency(pa_stream *s, pa_usec_t *r_usec, int *negative); /** Return the latest raw timing data structure. The returned pointer * points to an internal read-only instance of the timing * structure. The user should make a copy of this structure if he * wants to modify it. An in-place update to this data structure may * be requested using pa_stream_update_timing_info(). If no * pa_stream_update_timing_info() call was issued before, this * function will fail with PA_ERR_NODATA. Please note that the * write_index member field (and only this field) is updated on each * pa_stream_write() call, not just when a timing update has been * recieved. \since 0.8 */ const pa_timing_info* pa_stream_get_timing_info(pa_stream *s); /** Return a pointer to the stream's sample specification. \since 0.6 */ const pa_sample_spec* pa_stream_get_sample_spec(pa_stream *s); /** Return a pointer to the stream's channel map. \since 0.8 */ const pa_channel_map* pa_stream_get_channel_map(pa_stream *s); /** Return the buffer metrics of the stream. Only valid after the * stream has been connected successfuly and if the server is at least * PulseAudio 0.9. \since 0.9.0 */ const pa_buffer_attr* pa_stream_get_buffer_attr(pa_stream *s); PA_C_DECL_END #endif