Wed Aug 18 22:33:52 2010

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/time.h>
00033 
00034 #include "asterisk/endian.h"
00035 #include "asterisk/linkedlists.h"
00036 
00037 struct ast_codec_pref {
00038    char order[32];
00039    char framing[32];
00040 };
00041 
00042 /*! \page Def_Frame AST Multimedia and signalling frames
00043    \section Def_AstFrame What is an ast_frame ?
00044    A frame of data read used to communicate between 
00045    between channels and applications.
00046    Frames are divided into frame types and subclasses.
00047 
00048    \par Frame types 
00049    \arg \b VOICE: Voice data, subclass is codec (AST_FORMAT_*)
00050    \arg \b VIDEO: Video data, subclass is codec (AST_FORMAT_*)
00051    \arg \b DTMF:  A DTMF digit, subclass is the digit
00052    \arg \b IMAGE: Image transport, mostly used in IAX
00053    \arg \b TEXT:  Text messages and character by character (real time text)
00054    \arg \b HTML:  URL's and web pages
00055    \arg \b MODEM: Modulated data encodings, such as T.38 and V.150
00056    \arg \b IAX:   Private frame type for the IAX protocol
00057    \arg \b CNG:   Comfort noice frames
00058    \arg \b CONTROL:  A control frame, subclass defined as AST_CONTROL_
00059    \arg \b NULL:  Empty, useless frame
00060 
00061    \par Files
00062    \arg frame.h   Definitions
00063    \arg frame.c   Function library
00064    \arg \ref Def_Channel Asterisk channels
00065    \section Def_ControlFrame Control Frames
00066    Control frames send signalling information between channels
00067    and devices. They are prefixed with AST_CONTROL_, like AST_CONTROL_FRAME_HANGUP
00068    \arg \b HANGUP The other end has hungup
00069    \arg \b RING   Local ring
00070    \arg \b RINGING   The other end is ringing
00071    \arg \b ANSWER The other end has answered
00072    \arg \b BUSY   Remote end is busy
00073    \arg \b TAKEOFFHOOK  Make it go off hook (what's "it" ? )
00074    \arg \b OFFHOOK   Line is off hook
00075    \arg \b CONGESTION   Congestion (circuit is busy, not available)
00076    \arg \b FLASH  Other end sends flash hook
00077    \arg \b WINK   Other end sends wink
00078    \arg \b OPTION Send low-level option
00079    \arg \b RADIO_KEY Key radio (see app_rpt.c)
00080    \arg \b RADIO_UNKEY  Un-key radio (see app_rpt.c)
00081    \arg \b PROGRESS  Other end indicates call progress
00082    \arg \b PROCEEDING   Indicates proceeding
00083    \arg \b HOLD   Call is placed on hold
00084    \arg \b UNHOLD Call is back from hold
00085    \arg \b VIDUPDATE Video update requested
00086    \arg \b SRCUPDATE The source of media has changed (RTP marker bit must change)
00087    \arg \b SRCCHANGE Media source has changed (RTP marker bit and SSRC must change)
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  *       This is because these constants are transmitted directly over IAX2.
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 };
00131 
00132 /*! \brief Data structure associated with a single frame of data
00133  */
00134 struct ast_frame {
00135    /*! Kind of frame */
00136    enum ast_frame_type frametype;            
00137    /*! Subclass, frame dependent */
00138    int subclass;           
00139    /*! Length of data */
00140    int datalen;            
00141    /*! Number of samples in this frame */
00142    int samples;            
00143    /*! Was the data malloc'd?  i.e. should we free it when we discard the frame? */
00144    int mallocd;            
00145    /*! The number of bytes allocated for a malloc'd frame header */
00146    size_t mallocd_hdr_len;
00147    /*! How many bytes exist _before_ "data" that can be used if needed */
00148    int offset;          
00149    /*! Optional source of frame for debugging */
00150    const char *src;           
00151    /*! Pointer to actual data */
00152    union { void *ptr; uint32_t uint32; char pad[8]; } data;
00153    /*! Global delivery time */      
00154    struct timeval delivery;
00155    /*! For placing in a linked list */
00156    AST_LIST_ENTRY(ast_frame) frame_list;
00157    /*! Misc. frame flags */
00158    unsigned int flags;
00159    /*! Timestamp in milliseconds */
00160    long ts;
00161    /*! Length in milliseconds */
00162    long len;
00163    /*! Sequence number */
00164    int seqno;
00165 };
00166 
00167 /*!
00168  * Set the various field of a frame to point to a buffer.
00169  * Typically you set the base address of the buffer, the offset as
00170  * AST_FRIENDLY_OFFSET, and the datalen as the amount of bytes queued.
00171  * The remaining things (to be done manually) is set the number of
00172  * samples, which cannot be derived from the datalen unless you know
00173  * the number of bits per sample.
00174  */
00175 #define  AST_FRAME_SET_BUFFER(fr, _base, _ofs, _datalen) \
00176    {              \
00177    (fr)->data.ptr = (char *)_base + (_ofs);  \
00178    (fr)->offset = (_ofs);        \
00179    (fr)->datalen = (_datalen);      \
00180    }
00181 
00182 /*! Queueing a null frame is fairly common, so we declare a global null frame object
00183     for this purpose instead of having to declare one on the stack */
00184 extern struct ast_frame ast_null_frame;
00185 
00186 /*! \brief Offset into a frame's data buffer.
00187  *
00188  * By providing some "empty" space prior to the actual data of an ast_frame,
00189  * this gives any consumer of the frame ample space to prepend other necessary
00190  * information without having to create a new buffer.
00191  *
00192  * As an example, RTP can use the data from an ast_frame and simply prepend the
00193  * RTP header information into the space provided by AST_FRIENDLY_OFFSET instead
00194  * of having to create a new buffer with the necessary space allocated.
00195  */
00196 #define AST_FRIENDLY_OFFSET   64 
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 /*! Unsupported audio bits */
00260 #define AST_FORMAT_AUDIO_UNDEFINED  ((1 << 13) | (1 << 14))
00261 /*! Raw 16-bit Signed Linear (16000 Hz) PCM */
00262 #define AST_FORMAT_SLINEAR16  (1 << 15)
00263 /*! Maximum audio mask */
00264 #define AST_FORMAT_AUDIO_MASK   ((1 << 16)-1)
00265 /*! JPEG Images */
00266 #define AST_FORMAT_JPEG    (1 << 16)
00267 /*! PNG Images */
00268 #define AST_FORMAT_PNG     (1 << 17)
00269 /*! H.261 Video */
00270 #define AST_FORMAT_H261    (1 << 18)
00271 /*! H.263 Video */
00272 #define AST_FORMAT_H263    (1 << 19)
00273 /*! H.263+ Video */
00274 #define AST_FORMAT_H263_PLUS  (1 << 20)
00275 /*! H.264 Video */
00276 #define AST_FORMAT_H264    (1 << 21)
00277 /*! MPEG4 Video */
00278 #define AST_FORMAT_MP4_VIDEO  (1 << 22)
00279 #define AST_FORMAT_VIDEO_MASK   (((1 << 25)-1) & ~(AST_FORMAT_AUDIO_MASK))
00280 /*! T.140 RED Text format RFC 4103 */
00281 #define AST_FORMAT_T140RED      (1 << 26)
00282 /*! T.140 Text format - ITU T.140, RFC 4103 */
00283 #define AST_FORMAT_T140    (1 << 27)
00284 /*! Maximum text mask */
00285 #define AST_FORMAT_MAX_TEXT   (1 << 28))
00286 #define AST_FORMAT_TEXT_MASK   (((1 << 30)-1) & ~(AST_FORMAT_AUDIO_MASK) & ~(AST_FORMAT_VIDEO_MASK))
00287 
00288 enum ast_control_frame_type {
00289    AST_CONTROL_HANGUP = 1,    /*!< Other end has hungup */
00290    AST_CONTROL_RING = 2,      /*!< Local ring */
00291    AST_CONTROL_RINGING = 3,   /*!< Remote end is ringing */
00292    AST_CONTROL_ANSWER = 4,    /*!< Remote end has answered */
00293    AST_CONTROL_BUSY = 5,      /*!< Remote end is busy */
00294    AST_CONTROL_TAKEOFFHOOK = 6,  /*!< Make it go off hook */
00295    AST_CONTROL_OFFHOOK = 7,   /*!< Line is off hook */
00296    AST_CONTROL_CONGESTION = 8,   /*!< Congestion (circuits busy) */
00297    AST_CONTROL_FLASH = 9,     /*!< Flash hook */
00298    AST_CONTROL_WINK = 10,     /*!< Wink */
00299    AST_CONTROL_OPTION = 11,   /*!< Set a low-level option */
00300    AST_CONTROL_RADIO_KEY = 12,   /*!< Key Radio */
00301    AST_CONTROL_RADIO_UNKEY = 13, /*!< Un-Key Radio */
00302    AST_CONTROL_PROGRESS = 14, /*!< Indicate PROGRESS */
00303    AST_CONTROL_PROCEEDING = 15,  /*!< Indicate CALL PROCEEDING */
00304    AST_CONTROL_HOLD = 16,     /*!< Indicate call is placed on hold */
00305    AST_CONTROL_UNHOLD = 17,   /*!< Indicate call is left from hold */
00306    AST_CONTROL_VIDUPDATE = 18,   /*!< Indicate video frame update */
00307    _XXX_AST_CONTROL_T38 = 19, /*!< T38 state change request/notification \deprecated This is no longer supported. Use AST_CONTROL_T38_PARAMETERS instead. */
00308    AST_CONTROL_SRCUPDATE = 20,     /*!< Indicate source of media has changed */
00309    AST_CONTROL_T38_PARAMETERS = 24, /*!< T38 state change request/notification with parameters */
00310    AST_CONTROL_SRCCHANGE = 25,  /*!< Media source has changed and requires a new RTP SSRC */
00311 };
00312 
00313 enum ast_control_t38 {
00314    AST_T38_REQUEST_NEGOTIATE = 1,   /*!< Request T38 on a channel (voice to fax) */
00315    AST_T38_REQUEST_TERMINATE, /*!< Terminate T38 on a channel (fax to voice) */
00316    AST_T38_NEGOTIATED,     /*!< T38 negotiated (fax mode) */
00317    AST_T38_TERMINATED,     /*!< T38 terminated (back to voice) */
00318    AST_T38_REFUSED         /*!< T38 refused for some reason (usually rejected by remote end) */
00319 };
00320 
00321 enum ast_control_t38_rate {
00322    AST_T38_RATE_2400 = 0,
00323    AST_T38_RATE_4800,
00324    AST_T38_RATE_7200,
00325    AST_T38_RATE_9600,
00326    AST_T38_RATE_12000,
00327    AST_T38_RATE_14400,
00328 };
00329 
00330 enum ast_control_t38_rate_management {
00331    AST_T38_RATE_MANAGEMENT_TRANSFERRED_TCF = 0,
00332    AST_T38_RATE_MANAGEMENT_LOCAL_TCF,
00333 };
00334 
00335 struct ast_control_t38_parameters {
00336    enum ast_control_t38 request_response;       /*!< Request or response of the T38 control frame */
00337    unsigned int version;               /*!< Supported T.38 version */
00338    unsigned int max_ifp;               /*!< Maximum IFP size supported */
00339    enum ast_control_t38_rate rate;           /*!< Maximum fax rate supported */
00340    enum ast_control_t38_rate_management rate_management; /*!< Rate management setting */
00341    unsigned int fill_bit_removal:1;       /*!< Set if fill bit removal can be used */
00342    unsigned int transcoding_mmr:1;           /*!< Set if MMR transcoding can be used */
00343    unsigned int transcoding_jbig:1;       /*!< Set if JBIG transcoding can be used */
00344 };
00345 
00346 #define AST_SMOOTHER_FLAG_G729      (1 << 0)
00347 #define AST_SMOOTHER_FLAG_BE     (1 << 1)
00348 
00349 /* Option identifiers and flags */
00350 #define AST_OPTION_FLAG_REQUEST     0
00351 #define AST_OPTION_FLAG_ACCEPT      1
00352 #define AST_OPTION_FLAG_REJECT      2
00353 #define AST_OPTION_FLAG_QUERY    4
00354 #define AST_OPTION_FLAG_ANSWER      5
00355 #define AST_OPTION_FLAG_WTF      6
00356 
00357 /*! Verify touchtones by muting audio transmission 
00358    (and reception) and verify the tone is still present */
00359 #define AST_OPTION_TONE_VERIFY      1     
00360 
00361 /*! Put a compatible channel into TDD (TTY for the hearing-impared) mode */
00362 #define  AST_OPTION_TDD       2
00363 
00364 /*! Relax the parameters for DTMF reception (mainly for radio use) */
00365 #define  AST_OPTION_RELAXDTMF    3
00366 
00367 /*! Set (or clear) Audio (Not-Clear) Mode */
00368 #define  AST_OPTION_AUDIO_MODE      4
00369 
00370 /*! Set channel transmit gain 
00371  * Option data is a single signed char
00372    representing number of decibels (dB)
00373    to set gain to (on top of any gain
00374    specified in channel driver)
00375 */
00376 #define AST_OPTION_TXGAIN     5
00377 
00378 /*! Set channel receive gain
00379  * Option data is a single signed char
00380    representing number of decibels (dB)
00381    to set gain to (on top of any gain
00382    specified in channel driver)
00383 */
00384 #define AST_OPTION_RXGAIN     6
00385 
00386 /* set channel into "Operator Services" mode */
00387 #define  AST_OPTION_OPRMODE      7
00388 
00389 /*! Explicitly enable or disable echo cancelation for the given channel */
00390 #define  AST_OPTION_ECHOCAN      8
00391 
00392 /* !
00393  * Read-only. Allows query current status of T38 on the channel.
00394  * data: ast_t38state
00395  */
00396 #define AST_OPTION_T38_STATE     10
00397 
00398 struct oprmode {
00399    struct ast_channel *peer;
00400    int mode;
00401 } ;
00402 
00403 struct ast_option_header {
00404    /* Always keep in network byte order */
00405 #if __BYTE_ORDER == __BIG_ENDIAN
00406         uint16_t flag:3;
00407         uint16_t option:13;
00408 #else
00409 #if __BYTE_ORDER == __LITTLE_ENDIAN
00410         uint16_t option:13;
00411         uint16_t flag:3;
00412 #else
00413 #error Byte order not defined
00414 #endif
00415 #endif
00416       uint8_t data[0];
00417 };
00418 
00419 
00420 /*! \brief Definition of supported media formats (codecs) */
00421 struct ast_format_list {
00422    int bits;   /*!< bitmask value */
00423    char *name; /*!< short name */
00424    int samplespersecond; /*!< Number of samples per second (8000/16000) */
00425    char *desc; /*!< Description */
00426    int fr_len; /*!< Single frame length in bytes */
00427    int min_ms; /*!< Min value */
00428    int max_ms; /*!< Max value */
00429    int inc_ms; /*!< Increment */
00430    int def_ms; /*!< Default value */
00431    unsigned int flags;  /*!< Smoother flags */
00432    int cur_ms; /*!< Current value */
00433 };
00434 
00435 
00436 /*! \brief  Requests a frame to be allocated 
00437  * 
00438  * \param source 
00439  * Request a frame be allocated.  source is an optional source of the frame, 
00440  * len is the requested length, or "0" if the caller will supply the buffer 
00441  */
00442 #if 0 /* Unimplemented */
00443 struct ast_frame *ast_fralloc(char *source, int len);
00444 #endif
00445 
00446 /*!  
00447  * \brief Frees a frame or list of frames
00448  * 
00449  * \param fr Frame to free, or head of list to free
00450  * \param cache Whether to consider this frame for frame caching
00451  */
00452 void ast_frame_free(struct ast_frame *fr, int cache);
00453 
00454 #define ast_frfree(fr) ast_frame_free(fr, 1)
00455 
00456 /*! \brief Makes a frame independent of any static storage
00457  * \param fr frame to act upon
00458  * Take a frame, and if it's not been malloc'd, make a malloc'd copy
00459  * and if the data hasn't been malloced then make the
00460  * data malloc'd.  If you need to store frames, say for queueing, then
00461  * you should call this function.
00462  * \return Returns a frame on success, NULL on error
00463  * \note This function may modify the frame passed to it, so you must
00464  * not assume the frame will be intact after the isolated frame has
00465  * been produced. In other words, calling this function on a frame
00466  * should be the last operation you do with that frame before freeing
00467  * it (or exiting the block, if the frame is on the stack.)
00468  */
00469 struct ast_frame *ast_frisolate(struct ast_frame *fr);
00470 
00471 /*! \brief Copies a frame 
00472  * \param fr frame to copy
00473  * Duplicates a frame -- should only rarely be used, typically frisolate is good enough
00474  * \return Returns a frame on success, NULL on error
00475  */
00476 struct ast_frame *ast_frdup(const struct ast_frame *fr);
00477 
00478 void ast_swapcopy_samples(void *dst, const void *src, int samples);
00479 
00480 /* Helpers for byteswapping native samples to/from 
00481    little-endian and big-endian. */
00482 #if __BYTE_ORDER == __LITTLE_ENDIAN
00483 #define ast_frame_byteswap_le(fr) do { ; } while(0)
00484 #define ast_frame_byteswap_be(fr) do { struct ast_frame *__f = (fr); ast_swapcopy_samples(__f->data.ptr, __f->data.ptr, __f->samples); } while(0)
00485 #else
00486 #define ast_frame_byteswap_le(fr) do { struct ast_frame *__f = (fr); ast_swapcopy_samples(__f->data.ptr, __f->data.ptr, __f->samples); } while(0)
00487 #define ast_frame_byteswap_be(fr) do { ; } while(0)
00488 #endif
00489 
00490 
00491 /*! \brief Get the name of a format
00492  * \param format id of format
00493  * \return A static string containing the name of the format or "unknown" if unknown.
00494  */
00495 char* ast_getformatname(int format);
00496 
00497 /*! \brief Get the names of a set of formats
00498  * \param buf a buffer for the output string
00499  * \param size size of buf (bytes)
00500  * \param format the format (combined IDs of codecs)
00501  * Prints a list of readable codec names corresponding to "format".
00502  * ex: for format=AST_FORMAT_GSM|AST_FORMAT_SPEEX|AST_FORMAT_ILBC it will return "0x602 (GSM|SPEEX|ILBC)"
00503  * \return The return value is buf.
00504  */
00505 char* ast_getformatname_multiple(char *buf, size_t size, int format);
00506 
00507 /*!
00508  * \brief Gets a format from a name.
00509  * \param name string of format
00510  * \return This returns the form of the format in binary on success, 0 on error.
00511  */
00512 int ast_getformatbyname(const char *name);
00513 
00514 /*! \brief Get a name from a format 
00515  * Gets a name from a format
00516  * \param codec codec number (1,2,4,8,16,etc.)
00517  * \return This returns a static string identifying the format on success, 0 on error.
00518  */
00519 char *ast_codec2str(int codec);
00520 
00521 /*! \name AST_Smoother 
00522 */
00523 /*@{ */
00524 /*! \page ast_smooth The AST Frame Smoother
00525 The ast_smoother interface was designed specifically
00526 to take frames of variant sizes and produce frames of a single expected
00527 size, precisely what you want to do.
00528 
00529 The basic interface is:
00530 
00531 - Initialize with ast_smoother_new()
00532 - Queue input frames with ast_smoother_feed()
00533 - Get output frames with ast_smoother_read()
00534 - when you're done, free the structure with ast_smoother_free()
00535 - Also see ast_smoother_test_flag(), ast_smoother_set_flags(), ast_smoother_get_flags(), ast_smoother_reset()
00536 */
00537 struct ast_smoother;
00538 
00539 struct ast_smoother *ast_smoother_new(int bytes);
00540 void ast_smoother_set_flags(struct ast_smoother *smoother, int flags);
00541 int ast_smoother_get_flags(struct ast_smoother *smoother);
00542 int ast_smoother_test_flag(struct ast_smoother *s, int flag);
00543 void ast_smoother_free(struct ast_smoother *s);
00544 void ast_smoother_reset(struct ast_smoother *s, int bytes);
00545 
00546 /*!
00547  * \brief Reconfigure an existing smoother to output a different number of bytes per frame
00548  * \param s the smoother to reconfigure
00549  * \param bytes the desired number of bytes per output frame
00550  * \return nothing
00551  *
00552  */
00553 void ast_smoother_reconfigure(struct ast_smoother *s, int bytes);
00554 
00555 int __ast_smoother_feed(struct ast_smoother *s, struct ast_frame *f, int swap);
00556 struct ast_frame *ast_smoother_read(struct ast_smoother *s);
00557 #define ast_smoother_feed(s,f) __ast_smoother_feed(s, f, 0)
00558 #if __BYTE_ORDER == __LITTLE_ENDIAN
00559 #define ast_smoother_feed_be(s,f) __ast_smoother_feed(s, f, 1)
00560 #define ast_smoother_feed_le(s,f) __ast_smoother_feed(s, f, 0)
00561 #else
00562 #define ast_smoother_feed_be(s,f) __ast_smoother_feed(s, f, 0)
00563 #define ast_smoother_feed_le(s,f) __ast_smoother_feed(s, f, 1)
00564 #endif
00565 /*@} Doxygen marker */
00566 
00567 struct ast_format_list *ast_get_format_list_index(int index);
00568 struct ast_format_list *ast_get_format_list(size_t *size);
00569 void ast_frame_dump(const char *name, struct ast_frame *f, char *prefix);
00570 
00571 /*! \page AudioCodecPref Audio Codec Preferences
00572 
00573    In order to negotiate audio codecs in the order they are configured
00574    in <channel>.conf for a device, we set up codec preference lists
00575    in addition to the codec capabilities setting. The capabilities
00576    setting is a bitmask of audio and video codecs with no internal
00577    order. This will reflect the offer given to the other side, where
00578    the prefered codecs will be added to the top of the list in the
00579    order indicated by the "allow" lines in the device configuration.
00580    
00581    Video codecs are not included in the preference lists since they
00582    can't be transcoded and we just have to pick whatever is supported
00583 */
00584 
00585 /*! 
00586  *\brief Initialize an audio codec preference to "no preference".
00587  * \arg \ref AudioCodecPref 
00588 */
00589 void ast_codec_pref_init(struct ast_codec_pref *pref);
00590 
00591 /*! 
00592  * \brief Codec located at a particular place in the preference index.
00593  * \arg \ref AudioCodecPref 
00594 */
00595 int ast_codec_pref_index(struct ast_codec_pref *pref, int index);
00596 
00597 /*! \brief Remove audio a codec from a preference list */
00598 void ast_codec_pref_remove(struct ast_codec_pref *pref, int format);
00599 
00600 /*! \brief Append a audio codec to a preference list, removing it first if it was already there 
00601 */
00602 int ast_codec_pref_append(struct ast_codec_pref *pref, int format);
00603 
00604 /*! \brief Prepend an audio codec to a preference list, removing it first if it was already there 
00605 */
00606 void ast_codec_pref_prepend(struct ast_codec_pref *pref, int format, int only_if_existing);
00607 
00608 /*! \brief Select the best audio format according to preference list from supplied options. 
00609    If "find_best" is non-zero then if nothing is found, the "Best" format of 
00610    the format list is selected, otherwise 0 is returned. */
00611 int ast_codec_choose(struct ast_codec_pref *pref, int formats, int find_best);
00612 
00613 /*! \brief Set packet size for codec
00614 */
00615 int ast_codec_pref_setsize(struct ast_codec_pref *pref, int format, int framems);
00616 
00617 /*! \brief Get packet size for codec
00618 */
00619 struct ast_format_list ast_codec_pref_getsize(struct ast_codec_pref *pref, int format);
00620 
00621 /*! \brief Parse an "allow" or "deny" line in a channel or device configuration 
00622         and update the capabilities mask and pref if provided.
00623    Video codecs are not added to codec preference lists, since we can not transcode
00624    \return Returns number of errors encountered during parsing
00625  */
00626 int ast_parse_allow_disallow(struct ast_codec_pref *pref, int *mask, const char *list, int allowing);
00627 
00628 /*! \brief Dump audio codec preference list into a string */
00629 int ast_codec_pref_string(struct ast_codec_pref *pref, char *buf, size_t size);
00630 
00631 /*! \brief Shift an audio codec preference list up or down 65 bytes so that it becomes an ASCII string */
00632 void ast_codec_pref_convert(struct ast_codec_pref *pref, char *buf, size_t size, int right);
00633 
00634 /*! \brief Returns the number of samples contained in the frame */
00635 int ast_codec_get_samples(struct ast_frame *f);
00636 
00637 /*! \brief Returns the number of bytes for the number of samples of the given format */
00638 int ast_codec_get_len(int format, int samples);
00639 
00640 /*! \brief Appends a frame to the end of a list of frames, truncating the maximum length of the list */
00641 struct ast_frame *ast_frame_enqueue(struct ast_frame *head, struct ast_frame *f, int maxlen, int dupe);
00642 
00643 
00644 /*! \brief Gets duration in ms of interpolation frame for a format */
00645 static inline int ast_codec_interp_len(int format) 
00646 { 
00647    return (format == AST_FORMAT_ILBC) ? 30 : 20;
00648 }
00649 
00650 /*!
00651   \brief Adjusts the volume of the audio samples contained in a frame.
00652   \param f The frame containing the samples (must be AST_FRAME_VOICE and AST_FORMAT_SLINEAR)
00653   \param adjustment The number of dB to adjust up or down.
00654   \return 0 for success, non-zero for an error
00655  */
00656 int ast_frame_adjust_volume(struct ast_frame *f, int adjustment);
00657 
00658 /*!
00659   \brief Sums two frames of audio samples.
00660   \param f1 The first frame (which will contain the result)
00661   \param f2 The second frame
00662   \return 0 for success, non-zero for an error
00663 
00664   The frames must be AST_FRAME_VOICE and must contain AST_FORMAT_SLINEAR samples,
00665   and must contain the same number of samples.
00666  */
00667 int ast_frame_slinear_sum(struct ast_frame *f1, struct ast_frame *f2);
00668 
00669 /*!
00670  * \brief Get the sample rate for a given format.
00671  */
00672 static force_inline int ast_format_rate(int format)
00673 {
00674    if (format == AST_FORMAT_G722 || format == AST_FORMAT_SLINEAR16)
00675       return 16000;
00676 
00677    return 8000;
00678 }
00679 
00680 #if defined(__cplusplus) || defined(c_plusplus)
00681 }
00682 #endif
00683 
00684 #endif /* _ASTERISK_FRAME_H */

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