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Asterisk developer's documentation


frame.h

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  * \brief Asterisk internal frame definitions.
00021  * \arg For an explanation of frames, see \ref Def_Frame
00022  * \arg Frames are send of Asterisk channels, see \ref Def_Channel
00023  */
00024 
00025 #ifndef _ASTERISK_FRAME_H
00026 #define _ASTERISK_FRAME_H
00027 
00028 #if defined(__cplusplus) || defined(c_plusplus)
00029 extern "C" {
00030 #endif
00031 
00032 #include <sys/types.h>
00033 #include <sys/time.h>
00034 
00035 #include "asterisk/compiler.h"
00036 #include "asterisk/endian.h"
00037 #include "asterisk/linkedlists.h"
00038 
00039 struct ast_codec_pref {
00040    char order[32];
00041    char framing[32];
00042 };
00043 
00044 /*! \page Def_Frame AST Multimedia and signalling frames
00045    \section Def_AstFrame What is an ast_frame ?
00046    A frame of data read used to communicate between 
00047    between channels and applications.
00048    Frames are divided into frame types and subclasses.
00049 
00050    \par Frame types 
00051    \arg \b VOICE: Voice data, subclass is codec (AST_FORMAT_*)
00052    \arg \b VIDEO: Video data, subclass is codec (AST_FORMAT_*)
00053    \arg \b DTMF:  A DTMF digit, subclass is the digit
00054    \arg \b IMAGE: Image transport, mostly used in IAX
00055    \arg \b TEXT:  Text messages
00056    \arg \b HTML:  URL's and web pages
00057    \arg \b MODEM: Modulated data encodings, such as T.38 and V.150
00058    \arg \b IAX:   Private frame type for the IAX protocol
00059    \arg \b CNG:   Comfort noice frames
00060    \arg \b CONTROL:  A control frame, subclass defined as AST_CONTROL_
00061    \arg \b NULL:  Empty, useless frame
00062 
00063    \par Files
00064    \arg frame.h   Definitions
00065    \arg frame.c   Function library
00066    \arg \ref Def_Channel Asterisk channels
00067    \section Def_ControlFrame Control Frames
00068    Control frames send signalling information between channels
00069    and devices. They are prefixed with AST_CONTROL_, like AST_CONTROL_FRAME_HANGUP
00070    \arg \b HANGUP The other end has hungup
00071    \arg \b RING   Local ring
00072    \arg \b RINGING   The other end is ringing
00073    \arg \b ANSWER The other end has answered
00074    \arg \b BUSY   Remote end is busy
00075    \arg \b TAKEOFFHOOK  Make it go off hook (what's "it" ? )
00076    \arg \b OFFHOOK   Line is off hook
00077    \arg \b CONGESTION   Congestion (circuit is busy, not available)
00078    \arg \b FLASH  Other end sends flash hook
00079    \arg \b WINK   Other end sends wink
00080    \arg \b OPTION Send low-level option
00081    \arg \b RADIO_KEY Key radio (see app_rpt.c)
00082    \arg \b RADIO_UNKEY  Un-key radio (see app_rpt.c)
00083    \arg \b PROGRESS  Other end indicates call progress
00084    \arg \b PROCEEDING   Indicates proceeding
00085    \arg \b HOLD   Call is placed on hold
00086    \arg \b UNHOLD Call is back from hold
00087    \arg \b VIDUPDATE Video update requested
00088    \arg \b SRCUPDATE       The source of media has changed
00089 
00090 */
00091 
00092 /*!
00093  * \brief Frame types 
00094  *
00095  * \note It is important that the values of each frame type are never changed,
00096  *       because it will break backwards compatability with older versions.
00097  */
00098 enum ast_frame_type {
00099    /*! DTMF end event, subclass is the digit */
00100    AST_FRAME_DTMF_END = 1,
00101    /*! Voice data, subclass is AST_FORMAT_* */
00102    AST_FRAME_VOICE,
00103    /*! Video frame, maybe?? :) */
00104    AST_FRAME_VIDEO,
00105    /*! A control frame, subclass is AST_CONTROL_* */
00106    AST_FRAME_CONTROL,
00107    /*! An empty, useless frame */
00108    AST_FRAME_NULL,
00109    /*! Inter Asterisk Exchange private frame type */
00110    AST_FRAME_IAX,
00111    /*! Text messages */
00112    AST_FRAME_TEXT,
00113    /*! Image Frames */
00114    AST_FRAME_IMAGE,
00115    /*! HTML Frame */
00116    AST_FRAME_HTML,
00117    /*! Comfort Noise frame (subclass is level of CNG in -dBov), 
00118        body may include zero or more 8-bit quantization coefficients */
00119    AST_FRAME_CNG,
00120    /*! Modem-over-IP data streams */
00121    AST_FRAME_MODEM,  
00122    /*! DTMF begin event, subclass is the digit */
00123    AST_FRAME_DTMF_BEGIN,
00124 };
00125 #define AST_FRAME_DTMF AST_FRAME_DTMF_END
00126 
00127 enum {
00128    /*! This frame contains valid timing information */
00129    AST_FRFLAG_HAS_TIMING_INFO = (1 << 0),
00130    /*! This frame came from a translator and is still the original frame.
00131     *  The translator can not be free'd if the frame inside of it still has
00132     *  this flag set. */
00133    AST_FRFLAG_FROM_TRANSLATOR = (1 << 1),
00134    /*! This frame came from a dsp and is still the original frame.
00135     *  The dsp cannot be free'd if the frame inside of it still has
00136     *  this flag set. */
00137    AST_FRFLAG_FROM_DSP = (1 << 2),
00138 };
00139 
00140 /*! \brief Data structure associated with a single frame of data
00141  */
00142 struct ast_frame {
00143    /*! Kind of frame */
00144    enum ast_frame_type frametype;            
00145    /*! Subclass, frame dependent */
00146    int subclass;           
00147    /*! Length of data */
00148    int datalen;            
00149    /*! Number of 8khz samples in this frame */
00150    int samples;            
00151    /*! Was the data malloc'd?  i.e. should we free it when we discard the frame? */
00152    int mallocd;            
00153    /*! The number of bytes allocated for a malloc'd frame header */
00154    size_t mallocd_hdr_len;
00155    /*! How many bytes exist _before_ "data" that can be used if needed */
00156    int offset;          
00157    /*! Optional source of frame for debugging */
00158    const char *src;           
00159    /*! Pointer to actual data */
00160    void *data;    
00161    /*! Global delivery time */      
00162    struct timeval delivery;
00163    /*! For placing in a linked list */
00164    AST_LIST_ENTRY(ast_frame) frame_list;
00165    /*! Misc. frame flags */
00166    unsigned int flags;
00167    /*! Timestamp in milliseconds */
00168    long ts;
00169    /*! Length in milliseconds */
00170    long len;
00171    /*! Sequence number */
00172    int seqno;
00173 };
00174 
00175 /*!
00176  * Set the various field of a frame to point to a buffer.
00177  * Typically you set the base address of the buffer, the offset as
00178  * AST_FRIENDLY_OFFSET, and the datalen as the amount of bytes queued.
00179  * The remaining things (to be done manually) is set the number of
00180  * samples, which cannot be derived from the datalen unless you know
00181  * the number of bits per sample.
00182  */
00183 #define  AST_FRAME_SET_BUFFER(fr, _base, _ofs, _datalen) \
00184    {              \
00185    (fr)->data = (char *)_base + (_ofs);   \
00186    (fr)->offset = (_ofs);        \
00187    (fr)->datalen = (_datalen);      \
00188    }
00189 
00190 /*! Queueing a null frame is fairly common, so we declare a global null frame object
00191     for this purpose instead of having to declare one on the stack */
00192 extern struct ast_frame ast_null_frame;
00193 
00194 #define AST_FRIENDLY_OFFSET   64 /*! It's polite for a a new frame to
00195                  have this number of bytes for additional
00196                  headers.  */
00197 #define AST_MIN_OFFSET     32 /*! Make sure we keep at least this much handy */
00198 
00199 /*! Need the header be free'd? */
00200 #define AST_MALLOCD_HDR    (1 << 0)
00201 /*! Need the data be free'd? */
00202 #define AST_MALLOCD_DATA   (1 << 1)
00203 /*! Need the source be free'd? (haha!) */
00204 #define AST_MALLOCD_SRC    (1 << 2)
00205 
00206 /* MODEM subclasses */
00207 /*! T.38 Fax-over-IP */
00208 #define AST_MODEM_T38      1
00209 /*! V.150 Modem-over-IP */
00210 #define AST_MODEM_V150     2
00211 
00212 /* HTML subclasses */
00213 /*! Sending a URL */
00214 #define AST_HTML_URL    1
00215 /*! Data frame */
00216 #define AST_HTML_DATA      2
00217 /*! Beginning frame */
00218 #define AST_HTML_BEGIN     4
00219 /*! End frame */
00220 #define AST_HTML_END    8
00221 /*! Load is complete */
00222 #define AST_HTML_LDCOMPLETE   16
00223 /*! Peer is unable to support HTML */
00224 #define AST_HTML_NOSUPPORT 17
00225 /*! Send URL, and track */
00226 #define AST_HTML_LINKURL   18
00227 /*! No more HTML linkage */
00228 #define AST_HTML_UNLINK    19
00229 /*! Reject link request */
00230 #define AST_HTML_LINKREJECT   20
00231 
00232 /* Data formats for capabilities and frames alike */
00233 /*! G.723.1 compression */
00234 #define AST_FORMAT_G723_1  (1 << 0)
00235 /*! GSM compression */
00236 #define AST_FORMAT_GSM     (1 << 1)
00237 /*! Raw mu-law data (G.711) */
00238 #define AST_FORMAT_ULAW    (1 << 2)
00239 /*! Raw A-law data (G.711) */
00240 #define AST_FORMAT_ALAW    (1 << 3)
00241 /*! ADPCM (G.726, 32kbps, AAL2 codeword packing) */
00242 #define AST_FORMAT_G726_AAL2  (1 << 4)
00243 /*! ADPCM (IMA) */
00244 #define AST_FORMAT_ADPCM   (1 << 5)
00245 /*! Raw 16-bit Signed Linear (8000 Hz) PCM */
00246 #define AST_FORMAT_SLINEAR (1 << 6)
00247 /*! LPC10, 180 samples/frame */
00248 #define AST_FORMAT_LPC10   (1 << 7)
00249 /*! G.729A audio */
00250 #define AST_FORMAT_G729A   (1 << 8)
00251 /*! SpeeX Free Compression */
00252 #define AST_FORMAT_SPEEX   (1 << 9)
00253 /*! iLBC Free Compression */
00254 #define AST_FORMAT_ILBC    (1 << 10)
00255 /*! ADPCM (G.726, 32kbps, RFC3551 codeword packing) */
00256 #define AST_FORMAT_G726    (1 << 11)
00257 /*! G.722 */
00258 #define AST_FORMAT_G722    (1 << 12)
00259 /*! Maximum audio format */
00260 #define AST_FORMAT_MAX_AUDIO  (1 << 15)
00261 /*! Maximum audio mask */
00262 #define AST_FORMAT_AUDIO_MASK   ((1 << 16)-1)
00263 /*! JPEG Images */
00264 #define AST_FORMAT_JPEG    (1 << 16)
00265 /*! PNG Images */
00266 #define AST_FORMAT_PNG     (1 << 17)
00267 /*! H.261 Video */
00268 #define AST_FORMAT_H261    (1 << 18)
00269 /*! H.263 Video */
00270 #define AST_FORMAT_H263    (1 << 19)
00271 /*! H.263+ Video */
00272 #define AST_FORMAT_H263_PLUS  (1 << 20)
00273 /*! H.264 Video */
00274 #define AST_FORMAT_H264    (1 << 21)
00275 /*! Maximum video format */
00276 #define AST_FORMAT_MAX_VIDEO  (1 << 24)
00277 #define AST_FORMAT_VIDEO_MASK   (((1 << 25)-1) & ~(AST_FORMAT_AUDIO_MASK))
00278 
00279 enum ast_control_frame_type {
00280    AST_CONTROL_HANGUP = 1,    /*!< Other end has hungup */
00281    AST_CONTROL_RING = 2,      /*!< Local ring */
00282    AST_CONTROL_RINGING = 3,   /*!< Remote end is ringing */
00283    AST_CONTROL_ANSWER = 4,    /*!< Remote end has answered */
00284    AST_CONTROL_BUSY = 5,      /*!< Remote end is busy */
00285    AST_CONTROL_TAKEOFFHOOK = 6,  /*!< Make it go off hook */
00286    AST_CONTROL_OFFHOOK = 7,   /*!< Line is off hook */
00287    AST_CONTROL_CONGESTION = 8,   /*!< Congestion (circuits busy) */
00288    AST_CONTROL_FLASH = 9,     /*!< Flash hook */
00289    AST_CONTROL_WINK = 10,     /*!< Wink */
00290    AST_CONTROL_OPTION = 11,   /*!< Set a low-level option */
00291    AST_CONTROL_RADIO_KEY = 12,   /*!< Key Radio */
00292    AST_CONTROL_RADIO_UNKEY = 13, /*!< Un-Key Radio */
00293    AST_CONTROL_PROGRESS = 14, /*!< Indicate PROGRESS */
00294    AST_CONTROL_PROCEEDING = 15,  /*!< Indicate CALL PROCEEDING */
00295    AST_CONTROL_HOLD = 16,     /*!< Indicate call is placed on hold */
00296    AST_CONTROL_UNHOLD = 17,   /*!< Indicate call is left from hold */
00297    AST_CONTROL_VIDUPDATE = 18,   /*!< Indicate video frame update */
00298    AST_CONTROL_SRCUPDATE = 20,     /*!< Indicate source of media has changed */
00299 };
00300 
00301 #define AST_SMOOTHER_FLAG_G729      (1 << 0)
00302 #define AST_SMOOTHER_FLAG_BE     (1 << 1)
00303 
00304 /* Option identifiers and flags */
00305 #define AST_OPTION_FLAG_REQUEST     0
00306 #define AST_OPTION_FLAG_ACCEPT      1
00307 #define AST_OPTION_FLAG_REJECT      2
00308 #define AST_OPTION_FLAG_QUERY    4
00309 #define AST_OPTION_FLAG_ANSWER      5
00310 #define AST_OPTION_FLAG_WTF      6
00311 
00312 /*! Verify touchtones by muting audio transmission 
00313    (and reception) and verify the tone is still present */
00314 #define AST_OPTION_TONE_VERIFY      1     
00315 
00316 /*! Put a compatible channel into TDD (TTY for the hearing-impared) mode */
00317 #define  AST_OPTION_TDD       2
00318 
00319 /*! Relax the parameters for DTMF reception (mainly for radio use) */
00320 #define  AST_OPTION_RELAXDTMF    3
00321 
00322 /*! Set (or clear) Audio (Not-Clear) Mode */
00323 #define  AST_OPTION_AUDIO_MODE      4
00324 
00325 /*! Set channel transmit gain 
00326  * Option data is a single signed char
00327    representing number of decibels (dB)
00328    to set gain to (on top of any gain
00329    specified in channel driver)
00330 */
00331 #define AST_OPTION_TXGAIN     5
00332 
00333 /*! Set channel receive gain
00334  * Option data is a single signed char
00335    representing number of decibels (dB)
00336    to set gain to (on top of any gain
00337    specified in channel driver)
00338 */
00339 #define AST_OPTION_RXGAIN     6
00340 
00341 /* set channel into "Operator Services" mode */
00342 #define  AST_OPTION_OPRMODE      7
00343 
00344 /*! Explicitly enable or disable echo cancelation for the given channel */
00345 #define  AST_OPTION_ECHOCAN      8
00346 
00347 struct oprmode {
00348    struct ast_channel *peer;
00349    int mode;
00350 } ;
00351 
00352 struct ast_option_header {
00353    /* Always keep in network byte order */
00354 #if __BYTE_ORDER == __BIG_ENDIAN
00355         uint16_t flag:3;
00356         uint16_t option:13;
00357 #else
00358 #if __BYTE_ORDER == __LITTLE_ENDIAN
00359         uint16_t option:13;
00360         uint16_t flag:3;
00361 #else
00362 #error Byte order not defined
00363 #endif
00364 #endif
00365       uint8_t data[0];
00366 };
00367 
00368 
00369 /*! \brief Definition of supported media formats (codecs) */
00370 struct ast_format_list {
00371    int visible;   /*!< Can we see this entry */
00372    int bits;   /*!< bitmask value */
00373    char *name; /*!< short name */
00374    char *desc; /*!< Description */
00375    int fr_len; /*!< Single frame length in bytes */
00376    int min_ms; /*!< Min value */
00377    int max_ms; /*!< Max value */
00378    int inc_ms; /*!< Increment */
00379    int def_ms; /*!< Default value */
00380    unsigned int flags;  /*!< Smoother flags */
00381    int cur_ms; /*!< Current value */
00382 };
00383 
00384 
00385 /*! \brief  Requests a frame to be allocated 
00386  * 
00387  * \param source 
00388  * Request a frame be allocated.  source is an optional source of the frame, 
00389  * len is the requested length, or "0" if the caller will supply the buffer 
00390  */
00391 #if 0 /* Unimplemented */
00392 struct ast_frame *ast_fralloc(char *source, int len);
00393 #endif
00394 
00395 /*!  
00396  * \brief Frees a frame 
00397  * 
00398  * \param fr Frame to free
00399  * \param cache Whether to consider this frame for frame caching
00400  */
00401 void ast_frame_free(struct ast_frame *fr, int cache);
00402 
00403 #define ast_frfree(fr) ast_frame_free(fr, 1)
00404 
00405 /*! \brief Makes a frame independent of any static storage
00406  * \param fr frame to act upon
00407  * Take a frame, and if it's not been malloc'd, make a malloc'd copy
00408  * and if the data hasn't been malloced then make the
00409  * data malloc'd.  If you need to store frames, say for queueing, then
00410  * you should call this function.
00411  * \return Returns a frame on success, NULL on error
00412  */
00413 struct ast_frame *ast_frisolate(struct ast_frame *fr);
00414 
00415 /*! \brief Copies a frame 
00416  * \param fr frame to copy
00417  * Duplicates a frame -- should only rarely be used, typically frisolate is good enough
00418  * \return Returns a frame on success, NULL on error
00419  */
00420 struct ast_frame *ast_frdup(const struct ast_frame *fr);
00421 
00422 void ast_swapcopy_samples(void *dst, const void *src, int samples);
00423 
00424 /* Helpers for byteswapping native samples to/from 
00425    little-endian and big-endian. */
00426 #if __BYTE_ORDER == __LITTLE_ENDIAN
00427 #define ast_frame_byteswap_le(fr) do { ; } while(0)
00428 #define ast_frame_byteswap_be(fr) do { struct ast_frame *__f = (fr); ast_swapcopy_samples(__f->data, __f->data, __f->samples); } while(0)
00429 #else
00430 #define ast_frame_byteswap_le(fr) do { struct ast_frame *__f = (fr); ast_swapcopy_samples(__f->data, __f->data, __f->samples); } while(0)
00431 #define ast_frame_byteswap_be(fr) do { ; } while(0)
00432 #endif
00433 
00434 
00435 /*! \brief Get the name of a format
00436  * \param format id of format
00437  * \return A static string containing the name of the format or "unknown" if unknown.
00438  */
00439 char* ast_getformatname(int format);
00440 
00441 /*! \brief Get the names of a set of formats
00442  * \param buf a buffer for the output string
00443  * \param size size of buf (bytes)
00444  * \param format the format (combined IDs of codecs)
00445  * Prints a list of readable codec names corresponding to "format".
00446  * ex: for format=AST_FORMAT_GSM|AST_FORMAT_SPEEX|AST_FORMAT_ILBC it will return "0x602 (GSM|SPEEX|ILBC)"
00447  * \return The return value is buf.
00448  */
00449 char* ast_getformatname_multiple(char *buf, size_t size, int format);
00450 
00451 /*!
00452  * \brief Gets a format from a name.
00453  * \param name string of format
00454  * \return This returns the form of the format in binary on success, 0 on error.
00455  */
00456 int ast_getformatbyname(const char *name);
00457 
00458 /*! \brief Get a name from a format 
00459  * Gets a name from a format
00460  * \param codec codec number (1,2,4,8,16,etc.)
00461  * \return This returns a static string identifying the format on success, 0 on error.
00462  */
00463 char *ast_codec2str(int codec);
00464 
00465 struct ast_smoother;
00466 
00467 struct ast_format_list *ast_get_format_list_index(int index);
00468 struct ast_format_list *ast_get_format_list(size_t *size);
00469 struct ast_smoother *ast_smoother_new(int bytes);
00470 void ast_smoother_set_flags(struct ast_smoother *smoother, int flags);
00471 int ast_smoother_get_flags(struct ast_smoother *smoother);
00472 int ast_smoother_test_flag(struct ast_smoother *s, int flag);
00473 void ast_smoother_free(struct ast_smoother *s);
00474 void ast_smoother_reset(struct ast_smoother *s, int bytes);
00475 int __ast_smoother_feed(struct ast_smoother *s, struct ast_frame *f, int swap);
00476 struct ast_frame *ast_smoother_read(struct ast_smoother *s);
00477 #define ast_smoother_feed(s,f) __ast_smoother_feed(s, f, 0)
00478 #if __BYTE_ORDER == __LITTLE_ENDIAN
00479 #define ast_smoother_feed_be(s,f) __ast_smoother_feed(s, f, 1)
00480 #define ast_smoother_feed_le(s,f) __ast_smoother_feed(s, f, 0)
00481 #else
00482 #define ast_smoother_feed_be(s,f) __ast_smoother_feed(s, f, 0)
00483 #define ast_smoother_feed_le(s,f) __ast_smoother_feed(s, f, 1)
00484 #endif
00485 
00486 void ast_frame_dump(const char *name, struct ast_frame *f, char *prefix);
00487 
00488 /*! \page AudioCodecPref Audio Codec Preferences
00489    In order to negotiate audio codecs in the order they are configured
00490    in <channel>.conf for a device, we set up codec preference lists
00491    in addition to the codec capabilities setting. The capabilities
00492    setting is a bitmask of audio and video codecs with no internal
00493    order. This will reflect the offer given to the other side, where
00494    the prefered codecs will be added to the top of the list in the
00495    order indicated by the "allow" lines in the device configuration.
00496    
00497    Video codecs are not included in the preference lists since they
00498    can't be transcoded and we just have to pick whatever is supported
00499 */
00500 
00501 /*! \brief Initialize an audio codec preference to "no preference" See \ref AudioCodecPref */
00502 void ast_codec_pref_init(struct ast_codec_pref *pref);
00503 
00504 /*! \brief Codec located at a particular place in the preference index See \ref AudioCodecPref */
00505 int ast_codec_pref_index(struct ast_codec_pref *pref, int index);
00506 
00507 /*! \brief Remove audio a codec from a preference list */
00508 void ast_codec_pref_remove(struct ast_codec_pref *pref, int format);
00509 
00510 /*! \brief Append a audio codec to a preference list, removing it first if it was already there 
00511 */
00512 int ast_codec_pref_append(struct ast_codec_pref *pref, int format);
00513 
00514 /*! \brief Prepend an audio codec to a preference list, removing it first if it was already there 
00515 */
00516 void ast_codec_pref_prepend(struct ast_codec_pref *pref, int format, int only_if_existing);
00517 
00518 /*! \brief Select the best audio format according to preference list from supplied options. 
00519    If "find_best" is non-zero then if nothing is found, the "Best" format of 
00520    the format list is selected, otherwise 0 is returned. */
00521 int ast_codec_choose(struct ast_codec_pref *pref, int formats, int find_best);
00522 
00523 /*! \brief Set packet size for codec
00524 */
00525 int ast_codec_pref_setsize(struct ast_codec_pref *pref, int format, int framems);
00526 
00527 /*! \brief Get packet size for codec
00528 */
00529 struct ast_format_list ast_codec_pref_getsize(struct ast_codec_pref *pref, int format);
00530 
00531 /*! \brief Parse an "allow" or "deny" line in a channel or device configuration 
00532         and update the capabilities mask and pref if provided.
00533    Video codecs are not added to codec preference lists, since we can not transcode
00534  */
00535 void ast_parse_allow_disallow(struct ast_codec_pref *pref, int *mask, const char *list, int allowing);
00536 
00537 /*! \brief Dump audio codec preference list into a string */
00538 int ast_codec_pref_string(struct ast_codec_pref *pref, char *buf, size_t size);
00539 
00540 /*! \brief Shift an audio codec preference list up or down 65 bytes so that it becomes an ASCII string */
00541 void ast_codec_pref_convert(struct ast_codec_pref *pref, char *buf, size_t size, int right);
00542 
00543 /*! \brief Returns the number of samples contained in the frame */
00544 int ast_codec_get_samples(struct ast_frame *f);
00545 
00546 /*! \brief Returns the number of bytes for the number of samples of the given format */
00547 int ast_codec_get_len(int format, int samples);
00548 
00549 /*! \brief Appends a frame to the end of a list of frames, truncating the maximum length of the list */
00550 struct ast_frame *ast_frame_enqueue(struct ast_frame *head, struct ast_frame *f, int maxlen, int dupe);
00551 
00552 
00553 /*! \brief Gets duration in ms of interpolation frame for a format */
00554 static inline int ast_codec_interp_len(int format) 
00555 { 
00556    return (format == AST_FORMAT_ILBC) ? 30 : 20;
00557 }
00558 
00559 /*!
00560   \brief Adjusts the volume of the audio samples contained in a frame.
00561   \param f The frame containing the samples (must be AST_FRAME_VOICE and AST_FORMAT_SLINEAR)
00562   \param adjustment The number of dB to adjust up or down.
00563   \return 0 for success, non-zero for an error
00564  */
00565 int ast_frame_adjust_volume(struct ast_frame *f, int adjustment);
00566 
00567 /*!
00568   \brief Sums two frames of audio samples.
00569   \param f1 The first frame (which will contain the result)
00570   \param f2 The second frame
00571   \return 0 for success, non-zero for an error
00572 
00573   The frames must be AST_FRAME_VOICE and must contain AST_FORMAT_SLINEAR samples,
00574   and must contain the same number of samples.
00575  */
00576 int ast_frame_slinear_sum(struct ast_frame *f1, struct ast_frame *f2);
00577 
00578 /*!
00579  * \brief Get the sample rate for a given format.
00580  */
00581 static force_inline int ast_format_rate(int format)
00582 {
00583    if (format == AST_FORMAT_G722)
00584       return 16000;
00585 
00586    return 8000;
00587 }
00588 
00589 #if defined(__cplusplus) || defined(c_plusplus)
00590 }
00591 #endif
00592 
00593 #endif /* _ASTERISK_FRAME_H */

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