Wed Aug 15 01:24:21 2007

Asterisk developer's documentation


frame.h

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

Generated on Wed Aug 15 01:24:21 2007 for Asterisk - the Open Source PBX by  doxygen 1.5.3