include/asterisk/frame.h

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 1999 - 2005, Digium, Inc.
   5  *
   6  * Mark Spencer <markster@digium.com>
   7  *
   8  * See http://www.asterisk.org for more information about
   9  * the Asterisk project. Please do not directly contact
  10  * any of the maintainers of this project for assistance;
  11  * the project provides a web site, mailing lists and IRC
  12  * channels for your use.
  13  *
  14  * This program is free software, distributed under the terms of
  15  * the GNU General Public License Version 2. See the LICENSE file
  16  * at the top of the source tree.
  17  */
  18
  19 /*! \file
  20  * \brief Asterisk internal frame definitions.
  21  * \arg For an explanation of frames, see \ref Def_Frame
  22  * \arg Frames are send of Asterisk channels, see \ref Def_Channel
  23  */
  24
  25 #ifndef _ASTERISK_FRAME_H
  26 #define _ASTERISK_FRAME_H
  27
  28 #if defined(__cplusplus) || defined(c_plusplus)
  29 extern "C" {
  30 #endif
  31
  32 #include <sys/types.h>
  33 #include <sys/time.h>
  34
  35 #include "asterisk/compiler.h"
  36 #include "asterisk/endian.h"
  37 #include "asterisk/linkedlists.h"
  38
  39 struct ast_codec_pref {
  40         char order[32];
  41         char framing[32];
  42 };
  43
  44 /*! \page Def_Frame AST Multimedia and signalling frames
  45         \section Def_AstFrame What is an ast_frame ?
  46         A frame of data read used to communicate between
  47         between channels and applications.
  48         Frames are divided into frame types and subclasses.
  49
  50         \par Frame types
  51         \arg \b VOICE:  Voice data, subclass is codec (AST_FORMAT_*)
  52         \arg \b VIDEO:  Video data, subclass is codec (AST_FORMAT_*)
  53         \arg \b DTMF:   A DTMF digit, subclass is the digit
  54         \arg \b IMAGE:  Image transport, mostly used in IAX
  55         \arg \b TEXT:   Text messages
  56         \arg \b HTML:   URL's and web pages
  57         \arg \b MODEM:  Modulated data encodings, such as T.38 and V.150
  58         \arg \b IAX:    Private frame type for the IAX protocol
  59         \arg \b CNG:    Comfort noice frames
  60         \arg \b CONTROL:        A control frame, subclass defined as AST_CONTROL_
  61         \arg \b NULL:   Empty, useless frame
  62
  63         \par Files
  64         \arg frame.h    Definitions
  65         \arg frame.c    Function library
  66         \arg \ref Def_Channel Asterisk channels
  67         \section Def_ControlFrame Control Frames
  68         Control frames send signalling information between channels
  69         and devices. They are prefixed with AST_CONTROL_, like AST_CONTROL_FRAME_HANGUP
  70         \arg \b HANGUP  The other end has hungup
  71         \arg \b RING    Local ring
  72         \arg \b RINGING The other end is ringing
  73         \arg \b ANSWER  The other end has answered
  74         \arg \b BUSY    Remote end is busy
  75         \arg \b TAKEOFFHOOK     Make it go off hook (what's "it" ? )
  76         \arg \b OFFHOOK Line is off hook
  77         \arg \b CONGESTION      Congestion (circuit is busy, not available)
  78         \arg \b FLASH   Other end sends flash hook
  79         \arg \b WINK    Other end sends wink
  80         \arg \b OPTION  Send low-level option
  81         \arg \b RADIO_KEY       Key radio (see app_rpt.c)
  82         \arg \b RADIO_UNKEY     Un-key radio (see app_rpt.c)
  83         \arg \b PROGRESS        Other end indicates call progress
  84         \arg \b PROCEEDING      Indicates proceeding
  85         \arg \b HOLD    Call is placed on hold
  86         \arg \b UNHOLD  Call is back from hold
  87         \arg \b VIDUPDATE       Video update requested
  88
  89 */
  90
  91 /*!
  92  * \brief Frame types
  93  *
  94  * \note It is important that the values of each frame type are never changed,
  95  *       because it will break backwards compatability with older versions.
  96  */
  97 enum ast_frame_type {
  98         /*! DTMF end event, subclass is the digit */
  99         AST_FRAME_DTMF_END = 1,
 100         /*! Voice data, subclass is AST_FORMAT_* */
 101         AST_FRAME_VOICE,
 102         /*! Video frame, maybe?? :) */
 103         AST_FRAME_VIDEO,
 104         /*! A control frame, subclass is AST_CONTROL_* */
 105         AST_FRAME_CONTROL,
 106         /*! An empty, useless frame */
 107         AST_FRAME_NULL,
 108         /*! Inter Asterisk Exchange private frame type */
 109         AST_FRAME_IAX,
 110         /*! Text messages */
 111         AST_FRAME_TEXT,
 112         /*! Image Frames */
 113         AST_FRAME_IMAGE,
 114         /*! HTML Frame */
 115         AST_FRAME_HTML,
 116         /*! Comfort Noise frame (subclass is level of CNG in -dBov),
 117             body may include zero or more 8-bit quantization coefficients */
 118         AST_FRAME_CNG,
 119         /*! Modem-over-IP data streams */
 120         AST_FRAME_MODEM,
 121         /*! DTMF begin event, subclass is the digit */
 122         AST_FRAME_DTMF_BEGIN,
 123 };
 124 #define AST_FRAME_DTMF AST_FRAME_DTMF_END
 125
 126 /*! \brief Data structure associated with a single frame of data
 127  */
 128 struct ast_frame {
 129         /*! Kind of frame */
 130         enum ast_frame_type frametype;
 131         /*! Subclass, frame dependent */
 132         int subclass;
 133         /*! Length of data */
 134         int datalen;
 135         /*! Number of 8khz samples in this frame */
 136         int samples;
 137         /*! Was the data malloc'd?  i.e. should we free it when we discard the frame? */
 138         int mallocd;
 139         /*! The number of bytes allocated for a malloc'd frame header */
 140         size_t mallocd_hdr_len;
 141         /*! How many bytes exist _before_ "data" that can be used if needed */
 142         int offset;
 143         /*! Optional source of frame for debugging */
 144         const char *src;
 145         /*! Pointer to actual data */
 146         void *data;
 147         /*! Global delivery time */
 148         struct timeval delivery;
 149         /*! For placing in a linked list */
 150         AST_LIST_ENTRY(ast_frame) frame_list;
 151         /*! Timing data flag */
 152         int has_timing_info;
 153         /*! Timestamp in milliseconds */
 154         long ts;
 155         /*! Length in milliseconds */
 156         long len;
 157         /*! Sequence number */
 158         int seqno;
 159 };
 160
 161 /*!
 162  * Set the various field of a frame to point to a buffer.
 163  * Typically you set the base address of the buffer, the offset as
 164  * AST_FRIENDLY_OFFSET, and the datalen as the amount of bytes queued.
 165  * The remaining things (to be done manually) is set the number of
 166  * samples, which cannot be derived from the datalen unless you know
 167  * the number of bits per sample.
 168  */
 169 #define AST_FRAME_SET_BUFFER(fr, _base, _ofs, _datalen) \
 170         {                                       \
 171         (fr)->data = (char *)_base + (_ofs);    \
 172         (fr)->offset = (_ofs);                  \
 173         (fr)->datalen = (_datalen);             \
 174         }
 175
 176 /*! Queueing a null frame is fairly common, so we declare a global null frame object
 177     for this purpose instead of having to declare one on the stack */
 178 extern struct ast_frame ast_null_frame;
 179
 180 #define AST_FRIENDLY_OFFSET     64      /*! It's polite for a a new frame to
 181                                           have this number of bytes for additional
 182                                           headers.  */
 183 #define AST_MIN_OFFSET          32      /*! Make sure we keep at least this much handy */
 184
 185 /*! Need the header be free'd? */
 186 #define AST_MALLOCD_HDR         (1 << 0)
 187 /*! Need the data be free'd? */
 188 #define AST_MALLOCD_DATA        (1 << 1)
 189 /*! Need the source be free'd? (haha!) */
 190 #define AST_MALLOCD_SRC         (1 << 2)
 191
 192 /* MODEM subclasses */
 193 /*! T.38 Fax-over-IP */
 194 #define AST_MODEM_T38           1
 195 /*! V.150 Modem-over-IP */
 196 #define AST_MODEM_V150          2
 197
 198 /* HTML subclasses */
 199 /*! Sending a URL */
 200 #define AST_HTML_URL            1
 201 /*! Data frame */
 202 #define AST_HTML_DATA           2
 203 /*! Beginning frame */
 204 #define AST_HTML_BEGIN          4
 205 /*! End frame */
 206 #define AST_HTML_END            8
 207 /*! Load is complete */
 208 #define AST_HTML_LDCOMPLETE     16
 209 /*! Peer is unable to support HTML */
 210 #define AST_HTML_NOSUPPORT      17
 211 /*! Send URL, and track */
 212 #define AST_HTML_LINKURL        18
 213 /*! No more HTML linkage */
 214 #define AST_HTML_UNLINK         19
 215 /*! Reject link request */
 216 #define AST_HTML_LINKREJECT     20
 217
 218 /* Data formats for capabilities and frames alike */
 219 /*! G.723.1 compression */
 220 #define AST_FORMAT_G723_1       (1 << 0)
 221 /*! GSM compression */
 222 #define AST_FORMAT_GSM          (1 << 1)
 223 /*! Raw mu-law data (G.711) */
 224 #define AST_FORMAT_ULAW         (1 << 2)
 225 /*! Raw A-law data (G.711) */
 226 #define AST_FORMAT_ALAW         (1 << 3)
 227 /*! ADPCM (G.726, 32kbps, AAL2 codeword packing) */
 228 #define AST_FORMAT_G726_AAL2    (1 << 4)
 229 /*! ADPCM (IMA) */
 230 #define AST_FORMAT_ADPCM        (1 << 5)
 231 /*! Raw 16-bit Signed Linear (8000 Hz) PCM */
 232 #define AST_FORMAT_SLINEAR      (1 << 6)
 233 /*! LPC10, 180 samples/frame */
 234 #define AST_FORMAT_LPC10        (1 << 7)
 235 /*! G.729A audio */
 236 #define AST_FORMAT_G729A        (1 << 8)
 237 /*! SpeeX Free Compression */
 238 #define AST_FORMAT_SPEEX        (1 << 9)
 239 /*! iLBC Free Compression */
 240 #define AST_FORMAT_ILBC         (1 << 10)
 241 /*! ADPCM (G.726, 32kbps, RFC3551 codeword packing) */
 242 #define AST_FORMAT_G726         (1 << 11)
 243 /*! G.722 */
 244 #define AST_FORMAT_G722         (1 << 12)
 245 /*! Maximum audio format */
 246 #define AST_FORMAT_MAX_AUDIO    (1 << 15)
 247 /*! Maximum audio mask */
 248 #define AST_FORMAT_AUDIO_MASK   ((1 << 16)-1)
 249 /*! JPEG Images */
 250 #define AST_FORMAT_JPEG         (1 << 16)
 251 /*! PNG Images */
 252 #define AST_FORMAT_PNG          (1 << 17)
 253 /*! H.261 Video */
 254 #define AST_FORMAT_H261         (1 << 18)
 255 /*! H.263 Video */
 256 #define AST_FORMAT_H263         (1 << 19)
 257 /*! H.263+ Video */
 258 #define AST_FORMAT_H263_PLUS    (1 << 20)
 259 /*! H.264 Video */
 260 #define AST_FORMAT_H264         (1 << 21)
 261 /*! Maximum video format */
 262 #define AST_FORMAT_MAX_VIDEO    (1 << 24)
 263 #define AST_FORMAT_VIDEO_MASK   (((1 << 25)-1) & ~(AST_FORMAT_AUDIO_MASK))
 264
 265 enum ast_control_frame_type {
 266         AST_CONTROL_HANGUP = 1,         /*!< Other end has hungup */
 267         AST_CONTROL_RING = 2,           /*!< Local ring */
 268         AST_CONTROL_RINGING = 3,        /*!< Remote end is ringing */
 269         AST_CONTROL_ANSWER = 4,         /*!< Remote end has answered */
 270         AST_CONTROL_BUSY = 5,           /*!< Remote end is busy */
 271         AST_CONTROL_TAKEOFFHOOK = 6,    /*!< Make it go off hook */
 272         AST_CONTROL_OFFHOOK = 7,        /*!< Line is off hook */
 273         AST_CONTROL_CONGESTION = 8,     /*!< Congestion (circuits busy) */
 274         AST_CONTROL_FLASH = 9,          /*!< Flash hook */
 275         AST_CONTROL_WINK = 10,          /*!< Wink */
 276         AST_CONTROL_OPTION = 11,        /*!< Set a low-level option */
 277         AST_CONTROL_RADIO_KEY = 12,     /*!< Key Radio */
 278         AST_CONTROL_RADIO_UNKEY = 13,   /*!< Un-Key Radio */
 279         AST_CONTROL_PROGRESS = 14,      /*!< Indicate PROGRESS */
 280         AST_CONTROL_PROCEEDING = 15,    /*!< Indicate CALL PROCEEDING */
 281         AST_CONTROL_HOLD = 16,          /*!< Indicate call is placed on hold */
 282         AST_CONTROL_UNHOLD = 17,        /*!< Indicate call is left from hold */
 283         AST_CONTROL_VIDUPDATE = 18,     /*!< Indicate video frame update */
 284 };
 285
 286 #define AST_SMOOTHER_FLAG_G729          (1 << 0)
 287 #define AST_SMOOTHER_FLAG_BE            (1 << 1)
 288
 289 /* Option identifiers and flags */
 290 #define AST_OPTION_FLAG_REQUEST         0
 291 #define AST_OPTION_FLAG_ACCEPT          1
 292 #define AST_OPTION_FLAG_REJECT          2
 293 #define AST_OPTION_FLAG_QUERY           4
 294 #define AST_OPTION_FLAG_ANSWER          5
 295 #define AST_OPTION_FLAG_WTF             6
 296
 297 /*! Verify touchtones by muting audio transmission
 298         (and reception) and verify the tone is still present */
 299 #define AST_OPTION_TONE_VERIFY          1
 300
 301 /*! Put a compatible channel into TDD (TTY for the hearing-impared) mode */
 302 #define AST_OPTION_TDD                  2
 303
 304 /*! Relax the parameters for DTMF reception (mainly for radio use) */
 305 #define AST_OPTION_RELAXDTMF            3
 306
 307 /*! Set (or clear) Audio (Not-Clear) Mode */
 308 #define AST_OPTION_AUDIO_MODE           4
 309
 310 /*! Set channel transmit gain
 311  * Option data is a single signed char
 312    representing number of decibels (dB)
 313    to set gain to (on top of any gain
 314    specified in channel driver)
 315 */
 316 #define AST_OPTION_TXGAIN               5
 317
 318 /*! Set channel receive gain
 319  * Option data is a single signed char
 320    representing number of decibels (dB)
 321    to set gain to (on top of any gain
 322    specified in channel driver)
 323 */
 324 #define AST_OPTION_RXGAIN               6
 325
 326 /* set channel into "Operator Services" mode */
 327 #define AST_OPTION_OPRMODE              7
 328
 329 /*! Explicitly enable or disable echo cancelation for the given channel */
 330 #define AST_OPTION_ECHOCAN              8
 331
 332 struct oprmode {
 333         struct ast_channel *peer;
 334         int mode;
 335 } ;
 336
 337 struct ast_option_header {
 338         /* Always keep in network byte order */
 339 #if __BYTE_ORDER == __BIG_ENDIAN
 340         uint16_t flag:3;
 341         uint16_t option:13;
 342 #else
 343 #if __BYTE_ORDER == __LITTLE_ENDIAN
 344         uint16_t option:13;
 345         uint16_t flag:3;
 346 #else
 347 #error Byte order not defined
 348 #endif
 349 #endif
 350                 uint8_t data[0];
 351 };
 352
 353
 354 /*! \brief Definition of supported media formats (codecs) */
 355 struct ast_format_list {
 356         int visible;    /*!< Can we see this entry */
 357         int bits;       /*!< bitmask value */
 358         char *name;     /*!< short name */
 359         char *desc;     /*!< Description */
 360         int fr_len;     /*!< Single frame length in bytes */
 361         int min_ms;     /*!< Min value */
 362         int max_ms;     /*!< Max value */
 363         int inc_ms;     /*!< Increment */
 364         int def_ms;     /*!< Default value */
 365         unsigned int flags;     /*!< Smoother flags */
 366         int cur_ms;     /*!< Current value */
 367 };
 368
 369
 370 /*! \brief  Requests a frame to be allocated
 371  *
 372  * \param source
 373  * Request a frame be allocated.  source is an optional source of the frame,
 374  * len is the requested length, or "0" if the caller will supply the buffer
 375  */
 376 #if 0 /* Unimplemented */
 377 struct ast_frame *ast_fralloc(char *source, int len);
 378 #endif
 379
 380 /*!
 381  * \brief Frees a frame
 382  *
 383  * \param fr Frame to free
 384  * \param cache Whether to consider this frame for frame caching
 385  */
 386 void ast_frame_free(struct ast_frame *fr, int cache);
 387
 388 static void force_inline ast_frfree(struct ast_frame *fr)
 389 {
 390         ast_frame_free(fr, 1);
 391 }
 392
 393 /*! \brief Makes a frame independent of any static storage
 394  * \param fr frame to act upon
 395  * Take a frame, and if it's not been malloc'd, make a malloc'd copy
 396  * and if the data hasn't been malloced then make the
 397  * data malloc'd.  If you need to store frames, say for queueing, then
 398  * you should call this function.
 399  * \return Returns a frame on success, NULL on error
 400  */
 401 struct ast_frame *ast_frisolate(struct ast_frame *fr);
 402
 403 /*! \brief Copies a frame
 404  * \param fr frame to copy
 405  * Duplicates a frame -- should only rarely be used, typically frisolate is good enough
 406  * \return Returns a frame on success, NULL on error
 407  */
 408 struct ast_frame *ast_frdup(const struct ast_frame *fr);
 409
 410 void ast_swapcopy_samples(void *dst, const void *src, int samples);
 411
 412 /* Helpers for byteswapping native samples to/from
 413    little-endian and big-endian. */
 414 #if __BYTE_ORDER == __LITTLE_ENDIAN
 415 #define ast_frame_byteswap_le(fr) do { ; } while(0)
 416 #define ast_frame_byteswap_be(fr) do { struct ast_frame *__f = (fr); ast_swapcopy_samples(__f->data, __f->data, __f->samples); } while(0)
 417 #else
 418 #define ast_frame_byteswap_le(fr) do { struct ast_frame *__f = (fr); ast_swapcopy_samples(__f->data, __f->data, __f->samples); } while(0)
 419 #define ast_frame_byteswap_be(fr) do { ; } while(0)
 420 #endif
 421
 422
 423 /*! \brief Get the name of a format
 424  * \param format id of format
 425  * \return A static string containing the name of the format or "UNKN" if unknown.
 426  */
 427 char* ast_getformatname(int format);
 428
 429 /*! \brief Get the names of a set of formats
 430  * \param buf a buffer for the output string
 431  * \param size size of buf (bytes)
 432  * \param format the format (combined IDs of codecs)
 433  * Prints a list of readable codec names corresponding to "format".
 434  * ex: for format=AST_FORMAT_GSM|AST_FORMAT_SPEEX|AST_FORMAT_ILBC it will return "0x602 (GSM|SPEEX|ILBC)"
 435  * \return The return value is buf.
 436  */
 437 char* ast_getformatname_multiple(char *buf, size_t size, int format);
 438
 439 /*!
 440  * \brief Gets a format from a name.
 441  * \param name string of format
 442  * \return This returns the form of the format in binary on success, 0 on error.
 443  */
 444 int ast_getformatbyname(const char *name);
 445
 446 /*! \brief Get a name from a format
 447  * Gets a name from a format
 448  * \param codec codec number (1,2,4,8,16,etc.)
 449  * \return This returns a static string identifying the format on success, 0 on error.
 450  */
 451 char *ast_codec2str(int codec);
 452
 453 struct ast_smoother;
 454
 455 struct ast_format_list *ast_get_format_list_index(int index);
 456 struct ast_format_list *ast_get_format_list(size_t *size);
 457 struct ast_smoother *ast_smoother_new(int bytes);
 458 void ast_smoother_set_flags(struct ast_smoother *smoother, int flags);
 459 int ast_smoother_get_flags(struct ast_smoother *smoother);
 460 int ast_smoother_test_flag(struct ast_smoother *s, int flag);
 461 void ast_smoother_free(struct ast_smoother *s);
 462 void ast_smoother_reset(struct ast_smoother *s, int bytes);
 463 int __ast_smoother_feed(struct ast_smoother *s, struct ast_frame *f, int swap);
 464 struct ast_frame *ast_smoother_read(struct ast_smoother *s);
 465 #define ast_smoother_feed(s,f) __ast_smoother_feed(s, f, 0)
 466 #if __BYTE_ORDER == __LITTLE_ENDIAN
 467 #define ast_smoother_feed_be(s,f) __ast_smoother_feed(s, f, 1)
 468 #define ast_smoother_feed_le(s,f) __ast_smoother_feed(s, f, 0)
 469 #else
 470 #define ast_smoother_feed_be(s,f) __ast_smoother_feed(s, f, 0)
 471 #define ast_smoother_feed_le(s,f) __ast_smoother_feed(s, f, 1)
 472 #endif
 473
 474 void ast_frame_dump(const char *name, struct ast_frame *f, char *prefix);
 475
 476 /*! \par AudioCodecPref Audio Codec Preferences
 477         In order to negotiate audio codecs in the order they are configured
 478         in <channel>.conf for a device, we set up codec preference lists
 479         in addition to the codec capabilities setting. The capabilities
 480         setting is a bitmask of audio and video codecs with no internal
 481         order. This will reflect the offer given to the other side, where
 482         the prefered codecs will be added to the top of the list in the
 483         order indicated by the "allow" lines in the device configuration.
 484
 485         Video codecs are not included in the preference lists since they
 486         can't be transcoded and we just have to pick whatever is supported
 487 */
 488
 489 /*! \brief Initialize an audio codec preference to "no preference" See \ref AudioCodecPref */
 490 void ast_codec_pref_init(struct ast_codec_pref *pref);
 491
 492 /*! \brief Codec located at a particular place in the preference index See \ref AudioCodecPref */
 493 int ast_codec_pref_index(struct ast_codec_pref *pref, int index);
 494
 495 /*! \brief Remove audio a codec from a preference list */
 496 void ast_codec_pref_remove(struct ast_codec_pref *pref, int format);
 497
 498 /*! \brief Append a audio codec to a preference list, removing it first if it was already there
 499 */
 500 int ast_codec_pref_append(struct ast_codec_pref *pref, int format);
 501
 502 /*! \brief Select the best audio format according to preference list from supplied options.
 503    If "find_best" is non-zero then if nothing is found, the "Best" format of
 504    the format list is selected, otherwise 0 is returned. */
 505 int ast_codec_choose(struct ast_codec_pref *pref, int formats, int find_best);
 506
 507 /*! \brief Set packet size for codec
 508 */
 509 int ast_codec_pref_setsize(struct ast_codec_pref *pref, int format, int framems);
 510
 511 /*! \brief Get packet size for codec
 512 */
 513 struct ast_format_list ast_codec_pref_getsize(struct ast_codec_pref *pref, int format);
 514
 515 /*! \brief Parse an "allow" or "deny" line in a channel or device configuration
 516         and update the capabilities mask and pref if provided.
 517         Video codecs are not added to codec preference lists, since we can not transcode
 518  */
 519 void ast_parse_allow_disallow(struct ast_codec_pref *pref, int *mask, const char *list, int allowing);
 520
 521 /*! \brief Dump audio codec preference list into a string */
 522 int ast_codec_pref_string(struct ast_codec_pref *pref, char *buf, size_t size);
 523
 524 /*! \brief Shift an audio codec preference list up or down 65 bytes so that it becomes an ASCII string */
 525 void ast_codec_pref_convert(struct ast_codec_pref *pref, char *buf, size_t size, int right);
 526
 527 /*! \brief Returns the number of samples contained in the frame */
 528 int ast_codec_get_samples(struct ast_frame *f);
 529
 530 /*! \brief Returns the number of bytes for the number of samples of the given format */
 531 int ast_codec_get_len(int format, int samples);
 532
 533 /*! \brief Appends a frame to the end of a list of frames, truncating the maximum length of the list */
 534 struct ast_frame *ast_frame_enqueue(struct ast_frame *head, struct ast_frame *f, int maxlen, int dupe);
 535
 536
 537 /*! \brief Gets duration in ms of interpolation frame for a format */
 538 static inline int ast_codec_interp_len(int format)
 539 {
 540         return (format == AST_FORMAT_ILBC) ? 30 : 20;
 541 }
 542
 543 /*!
 544   \brief Adjusts the volume of the audio samples contained in a frame.
 545   \param f The frame containing the samples (must be AST_FRAME_VOICE and AST_FORMAT_SLINEAR)
 546   \param adjustment The number of dB to adjust up or down.
 547   \return 0 for success, non-zero for an error
 548  */
 549 int ast_frame_adjust_volume(struct ast_frame *f, int adjustment);
 550
 551 /*!
 552   \brief Sums two frames of audio samples.
 553   \param f1 The first frame (which will contain the result)
 554   \param f2 The second frame
 555   \return 0 for success, non-zero for an error
 556
 557   The frames must be AST_FRAME_VOICE and must contain AST_FORMAT_SLINEAR samples,
 558   and must contain the same number of samples.
 559  */
 560 int ast_frame_slinear_sum(struct ast_frame *f1, struct ast_frame *f2);
 561
 562 #if defined(__cplusplus) || defined(c_plusplus)
 563 }
 564 #endif
 565
 566 #endif /* _ASTERISK_FRAME_H */