asterisk-dev 1:11.7.0~dfsg-1ubuntu1 / usr / include / asterisk / frame.h

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 * \brief Asterisk internal frame definitions.
 * \arg For an explanation of frames, see \ref Def_Frame
 * \arg Frames are send of Asterisk channels, see \ref Def_Channel
 */

#ifndef _ASTERISK_FRAME_H
#define _ASTERISK_FRAME_H

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

#include <sys/time.h>

#include "asterisk/format_pref.h"
#include "asterisk/format.h"
#include "asterisk/endian.h"
#include "asterisk/linkedlists.h"

/*!
 * \page Def_Frame AST Multimedia and signalling frames
 * \section Def_AstFrame What is an ast_frame ?
 * A frame of data read used to communicate between 
 * between channels and applications.
 * Frames are divided into frame types and subclasses.
 *
 * \par Frame types 
 * \arg \b VOICE:  Voice data, subclass is codec (AST_FORMAT_*)
 * \arg \b VIDEO:  Video data, subclass is codec (AST_FORMAT_*)
 * \arg \b DTMF:   A DTMF digit, subclass is the digit
 * \arg \b IMAGE:  Image transport, mostly used in IAX
 * \arg \b TEXT:   Text messages and character by character (real time text)
 * \arg \b HTML:   URL's and web pages
 * \arg \b MODEM:  Modulated data encodings, such as T.38 and V.150
 * \arg \b IAX:    Private frame type for the IAX protocol
 * \arg \b CNG:    Comfort noice frames
 * \arg \b CONTROL:A control frame, subclass defined as AST_CONTROL_
 * \arg \b NULL:   Empty, useless frame
 *
 * \par Files
 * \arg frame.h    Definitions
 * \arg frame.c    Function library
 * \arg \ref Def_Channel Asterisk channels
 * \section Def_ControlFrame Control Frames
 * Control frames send signalling information between channels
 * and devices. They are prefixed with AST_CONTROL_, like AST_CONTROL_FRAME_HANGUP
 * \arg \b HANGUP          The other end has hungup
 * \arg \b RING            Local ring
 * \arg \b RINGING         The other end is ringing
 * \arg \b ANSWER          The other end has answered
 * \arg \b BUSY            Remote end is busy
 * \arg \b TAKEOFFHOOK     Make it go off hook (what's "it" ? )
 * \arg \b OFFHOOK         Line is off hook
 * \arg \b CONGESTION      Congestion (circuit is busy, not available)
 * \arg \b FLASH           Other end sends flash hook
 * \arg \b WINK            Other end sends wink
 * \arg \b OPTION          Send low-level option
 * \arg \b RADIO_KEY       Key radio (see app_rpt.c)
 * \arg \b RADIO_UNKEY     Un-key radio (see app_rpt.c)
 * \arg \b PROGRESS        Other end indicates call progress
 * \arg \b PROCEEDING      Indicates proceeding
 * \arg \b HOLD            Call is placed on hold
 * \arg \b UNHOLD          Call is back from hold
 * \arg \b VIDUPDATE       Video update requested
 * \arg \b SRCUPDATE       The source of media has changed (RTP marker bit must change)
 * \arg \b SRCCHANGE       Media source has changed (RTP marker bit and SSRC must change)
 * \arg \b CONNECTED_LINE  Connected line has changed
 * \arg \b REDIRECTING     Call redirecting information has changed.
 */

/*!
 * \brief Frame types 
 *
 * \note It is important that the values of each frame type are never changed,
 *       because it will break backwards compatability with older versions.
 *       This is because these constants are transmitted directly over IAX2.
 */
enum ast_frame_type {
	/*! DTMF end event, subclass is the digit */
	AST_FRAME_DTMF_END = 1,
	/*! Voice data, subclass is AST_FORMAT_* */
	AST_FRAME_VOICE,
	/*! Video frame, maybe?? :) */
	AST_FRAME_VIDEO,
	/*! A control frame, subclass is AST_CONTROL_* */
	AST_FRAME_CONTROL,
	/*! An empty, useless frame */
	AST_FRAME_NULL,
	/*! Inter Asterisk Exchange private frame type */
	AST_FRAME_IAX,
	/*! Text messages */
	AST_FRAME_TEXT,
	/*! Image Frames */
	AST_FRAME_IMAGE,
	/*! HTML Frame */
	AST_FRAME_HTML,
	/*! Comfort Noise frame (subclass is level of CNG in -dBov), 
	    body may include zero or more 8-bit quantization coefficients */
	AST_FRAME_CNG,
	/*! Modem-over-IP data streams */
	AST_FRAME_MODEM,	
	/*! DTMF begin event, subclass is the digit */
	AST_FRAME_DTMF_BEGIN,
};
#define AST_FRAME_DTMF AST_FRAME_DTMF_END

enum {
	/*! This frame contains valid timing information */
	AST_FRFLAG_HAS_TIMING_INFO = (1 << 0),
};

union ast_frame_subclass {
	int integer;
	struct ast_format format;
};

/*! \brief Data structure associated with a single frame of data
 */
struct ast_frame {
	/*! Kind of frame */
	enum ast_frame_type frametype;				
	/*! Subclass, frame dependent */
	union ast_frame_subclass subclass;
	/*! Length of data */
	int datalen;				
	/*! Number of samples in this frame */
	int samples;				
	/*! Was the data malloc'd?  i.e. should we free it when we discard the frame? */
	int mallocd;				
	/*! The number of bytes allocated for a malloc'd frame header */
	size_t mallocd_hdr_len;
	/*! How many bytes exist _before_ "data" that can be used if needed */
	int offset;				
	/*! Optional source of frame for debugging */
	const char *src;				
	/*! Pointer to actual data */
	union { void *ptr; uint32_t uint32; char pad[8]; } data;
	/*! Global delivery time */		
	struct timeval delivery;
	/*! For placing in a linked list */
	AST_LIST_ENTRY(ast_frame) frame_list;
	/*! Misc. frame flags */
	unsigned int flags;
	/*! Timestamp in milliseconds */
	long ts;
	/*! Length in milliseconds */
	long len;
	/*! Sequence number */
	int seqno;
};

/*!
 * Set the various field of a frame to point to a buffer.
 * Typically you set the base address of the buffer, the offset as
 * AST_FRIENDLY_OFFSET, and the datalen as the amount of bytes queued.
 * The remaining things (to be done manually) is set the number of
 * samples, which cannot be derived from the datalen unless you know
 * the number of bits per sample.
 */
#define	AST_FRAME_SET_BUFFER(fr, _base, _ofs, _datalen)	\
	{					\
	(fr)->data.ptr = (char *)_base + (_ofs);	\
	(fr)->offset = (_ofs);			\
	(fr)->datalen = (_datalen);		\
	}

/*! Queueing a null frame is fairly common, so we declare a global null frame object
    for this purpose instead of having to declare one on the stack */
extern struct ast_frame ast_null_frame;

/*! \brief Offset into a frame's data buffer.
 *
 * By providing some "empty" space prior to the actual data of an ast_frame,
 * this gives any consumer of the frame ample space to prepend other necessary
 * information without having to create a new buffer.
 *
 * As an example, RTP can use the data from an ast_frame and simply prepend the
 * RTP header information into the space provided by AST_FRIENDLY_OFFSET instead
 * of having to create a new buffer with the necessary space allocated.
 */
#define AST_FRIENDLY_OFFSET 	64	
#define AST_MIN_OFFSET 		32	/*! Make sure we keep at least this much handy */

/*! Need the header be free'd? */
#define AST_MALLOCD_HDR		(1 << 0)
/*! Need the data be free'd? */
#define AST_MALLOCD_DATA	(1 << 1)
/*! Need the source be free'd? (haha!) */
#define AST_MALLOCD_SRC		(1 << 2)

/* MODEM subclasses */
/*! T.38 Fax-over-IP */
#define AST_MODEM_T38		1
/*! V.150 Modem-over-IP */
#define AST_MODEM_V150		2

/* HTML subclasses */
/*! Sending a URL */
#define AST_HTML_URL		1
/*! Data frame */
#define AST_HTML_DATA		2
/*! Beginning frame */
#define AST_HTML_BEGIN		4
/*! End frame */
#define AST_HTML_END		8
/*! Load is complete */
#define AST_HTML_LDCOMPLETE	16
/*! Peer is unable to support HTML */
#define AST_HTML_NOSUPPORT	17
/*! Send URL, and track */
#define AST_HTML_LINKURL	18
/*! No more HTML linkage */
#define AST_HTML_UNLINK		19
/*! Reject link request */
#define AST_HTML_LINKREJECT	20

enum ast_control_frame_type {
	AST_CONTROL_HANGUP = 1,			/*!< Other end has hungup */
	AST_CONTROL_RING = 2,			/*!< Local ring */
	AST_CONTROL_RINGING = 3,		/*!< Remote end is ringing */
	AST_CONTROL_ANSWER = 4,			/*!< Remote end has answered */
	AST_CONTROL_BUSY = 5,			/*!< Remote end is busy */
	AST_CONTROL_TAKEOFFHOOK = 6,	/*!< Make it go off hook */
	AST_CONTROL_OFFHOOK = 7,		/*!< Line is off hook */
	AST_CONTROL_CONGESTION = 8,		/*!< Congestion (circuits busy) */
	AST_CONTROL_FLASH = 9,			/*!< Flash hook */
	AST_CONTROL_WINK = 10,			/*!< Wink */
	AST_CONTROL_OPTION = 11,		/*!< Set a low-level option */
	AST_CONTROL_RADIO_KEY = 12,		/*!< Key Radio */
	AST_CONTROL_RADIO_UNKEY = 13,	/*!< Un-Key Radio */
	AST_CONTROL_PROGRESS = 14,		/*!< Indicate PROGRESS */
	AST_CONTROL_PROCEEDING = 15,	/*!< Indicate CALL PROCEEDING */
	AST_CONTROL_HOLD = 16,			/*!< Indicate call is placed on hold */
	AST_CONTROL_UNHOLD = 17,		/*!< Indicate call is left from hold */
	AST_CONTROL_VIDUPDATE = 18,		/*!< Indicate video frame update */
	_XXX_AST_CONTROL_T38 = 19,		/*!< T38 state change request/notification \deprecated This is no longer supported. Use AST_CONTROL_T38_PARAMETERS instead. */
	AST_CONTROL_SRCUPDATE = 20,		/*!< Indicate source of media has changed */
	AST_CONTROL_TRANSFER = 21,		/*!< Indicate status of a transfer request */
	AST_CONTROL_CONNECTED_LINE = 22,/*!< Indicate connected line has changed */
	AST_CONTROL_REDIRECTING = 23,	/*!< Indicate redirecting id has changed */
	AST_CONTROL_T38_PARAMETERS = 24,/*!< T38 state change request/notification with parameters */
	AST_CONTROL_CC = 25,			/*!< Indication that Call completion service is possible */
	AST_CONTROL_SRCCHANGE = 26,		/*!< Media source has changed and requires a new RTP SSRC */
	AST_CONTROL_READ_ACTION = 27,	/*!< Tell ast_read to take a specific action */
	AST_CONTROL_AOC = 28,			/*!< Advice of Charge with encoded generic AOC payload */
	AST_CONTROL_END_OF_Q = 29,		/*!< Indicate that this position was the end of the channel queue for a softhangup. */
	AST_CONTROL_INCOMPLETE = 30,	/*!< Indication that the extension dialed is incomplete */
	AST_CONTROL_MCID = 31,			/*!< Indicate that the caller is being malicious. */
	AST_CONTROL_UPDATE_RTP_PEER = 32, /*!< Interrupt the bridge and have it update the peer */
	AST_CONTROL_PVT_CAUSE_CODE = 33, /*!< Contains an update to the protocol-specific cause-code stored for branching dials */
};

enum ast_frame_read_action {
	AST_FRAME_READ_ACTION_CONNECTED_LINE_MACRO,
};

struct ast_control_read_action_payload {
	/* An indicator to ast_read of what action to
	 * take with the frame;
	 */
	enum ast_frame_read_action action;
	/* The size of the frame's payload
	 */
	size_t payload_size;
	/* A payload for the frame.
	 */
	unsigned char payload[0];
};

enum ast_control_t38 {
	AST_T38_REQUEST_NEGOTIATE = 1,	/*!< Request T38 on a channel (voice to fax) */
	AST_T38_REQUEST_TERMINATE,	/*!< Terminate T38 on a channel (fax to voice) */
	AST_T38_NEGOTIATED,		/*!< T38 negotiated (fax mode) */
	AST_T38_TERMINATED,		/*!< T38 terminated (back to voice) */
	AST_T38_REFUSED,		/*!< T38 refused for some reason (usually rejected by remote end) */
	AST_T38_REQUEST_PARMS,		/*!< request far end T.38 parameters for a channel in 'negotiating' state */
};

enum ast_control_t38_rate {
	AST_T38_RATE_2400 = 1,
	AST_T38_RATE_4800,
	AST_T38_RATE_7200,
	AST_T38_RATE_9600,
	AST_T38_RATE_12000,
	/* Set to 0 so it's taken as default when unspecified.
	 * See ITU-T T.38 Implementors' Guide (11 May 2012),
	 * Table H.2: if the T38MaxBitRate attribute is omitted
	 * it should use a default of 14400. */
	AST_T38_RATE_14400 = 0,
};

enum ast_control_t38_rate_management {
	AST_T38_RATE_MANAGEMENT_TRANSFERRED_TCF = 0,
	AST_T38_RATE_MANAGEMENT_LOCAL_TCF,
};

struct ast_control_t38_parameters {
	enum ast_control_t38 request_response;			/*!< Request or response of the T38 control frame */
	unsigned int version;					/*!< Supported T.38 version */
	unsigned int max_ifp; 					/*!< Maximum IFP size supported */
	enum ast_control_t38_rate rate;				/*!< Maximum fax rate supported */
	enum ast_control_t38_rate_management rate_management;	/*!< Rate management setting */
	unsigned int fill_bit_removal:1;			/*!< Set if fill bit removal can be used */
	unsigned int transcoding_mmr:1;				/*!< Set if MMR transcoding can be used */
	unsigned int transcoding_jbig:1;			/*!< Set if JBIG transcoding can be used */
};

enum ast_control_transfer {
	AST_TRANSFER_SUCCESS = 0, /*!< Transfer request on the channel worked */
	AST_TRANSFER_FAILED,      /*!< Transfer request on the channel failed */
};

struct ast_control_pvt_cause_code {
	char chan_name[AST_CHANNEL_NAME];	/*!< Name of the channel that originated the cause information */
	unsigned int emulate_sip_cause:1;	/*!< Indicates whether this should be used to emulate SIP_CAUSE support */
	int ast_cause;				/*!< Asterisk cause code associated with this message */
	char code[1];				/*!< Tech-specific cause code information, beginning with the name of the tech */
};

#define AST_SMOOTHER_FLAG_G729		(1 << 0)
#define AST_SMOOTHER_FLAG_BE		(1 << 1)

/* Option identifiers and flags */
#define AST_OPTION_FLAG_REQUEST		0
#define AST_OPTION_FLAG_ACCEPT		1
#define AST_OPTION_FLAG_REJECT		2
#define AST_OPTION_FLAG_QUERY		4
#define AST_OPTION_FLAG_ANSWER		5
#define AST_OPTION_FLAG_WTF		6

/*! Verify touchtones by muting audio transmission 
 * (and reception) and verify the tone is still present
 * Option data is a single signed char value 0 or 1 */
#define AST_OPTION_TONE_VERIFY		1		

/*! Put a compatible channel into TDD (TTY for the hearing-impared) mode
 * Option data is a single signed char value 0 or 1 */
#define	AST_OPTION_TDD			2

/*! Relax the parameters for DTMF reception (mainly for radio use)
 * Option data is a single signed char value 0 or 1 */
#define	AST_OPTION_RELAXDTMF		3

/*! Set (or clear) Audio (Not-Clear) Mode
 * Option data is a single signed char value 0 or 1 */
#define	AST_OPTION_AUDIO_MODE		4

/*! Set channel transmit gain 
 * Option data is a single signed char representing number of decibels (dB)
 * to set gain to (on top of any gain specified in channel driver) */
#define AST_OPTION_TXGAIN		5

/*! Set channel receive gain
 * Option data is a single signed char representing number of decibels (dB)
 * to set gain to (on top of any gain specified in channel driver) */
#define AST_OPTION_RXGAIN		6

/* set channel into "Operator Services" mode 
 * Option data is a struct oprmode
 *
 * \note This option should never be sent over the network */
#define	AST_OPTION_OPRMODE		7

/*! Explicitly enable or disable echo cancelation for the given channel
 * Option data is a single signed char value 0 or 1
 *
 * \note This option appears to be unused in the code. It is handled, but never
 * set or queried. */
#define	AST_OPTION_ECHOCAN		8

/*! \brief Handle channel write data
 * If a channel needs to process the data from a func_channel write operation
 * after func_channel_write executes, it can define the setoption callback
 * and process this option. A pointer to an ast_chan_write_info_t will be passed.
 *
 * \note This option should never be passed over the network. */
#define AST_OPTION_CHANNEL_WRITE 9

/* !
 * Read-only. Allows query current status of T38 on the channel.
 * data: ast_t38state
 */
#define AST_OPTION_T38_STATE		10

/*! Request that the channel driver deliver frames in a specific format
 * Option data is a format_t */
#define AST_OPTION_FORMAT_READ          11

/*! Request that the channel driver be prepared to accept frames in a specific format
 * Option data is a format_t */
#define AST_OPTION_FORMAT_WRITE         12

/*! Request that the channel driver make two channels of the same tech type compatible if possible
 * Option data is an ast_channel
 *
 * \note This option should never be passed over the network */
#define AST_OPTION_MAKE_COMPATIBLE      13

/*! Get or set the digit detection state of the channel
 * Option data is a single signed char value 0 or 1 */
#define AST_OPTION_DIGIT_DETECT		14

/*! Get or set the fax tone detection state of the channel
 * Option data is a single signed char value 0 or 1 */
#define AST_OPTION_FAX_DETECT		15

/*! Get the device name from the channel (Read only)
 * Option data is a character buffer of suitable length */
#define AST_OPTION_DEVICE_NAME		16

/*! Get the CC agent type from the channel (Read only) 
 * Option data is a character buffer of suitable length */
#define AST_OPTION_CC_AGENT_TYPE    17

/*! Get or set the security options on a channel
 * Option data is an integer value of 0 or 1 */
#define AST_OPTION_SECURE_SIGNALING        18
#define AST_OPTION_SECURE_MEDIA            19

struct oprmode {
	struct ast_channel *peer;
	int mode;
} ;

struct ast_option_header {
	/* Always keep in network byte order */
#if __BYTE_ORDER == __BIG_ENDIAN
        uint16_t flag:3;
        uint16_t option:13;
#else
#if __BYTE_ORDER == __LITTLE_ENDIAN
        uint16_t option:13;
        uint16_t flag:3;
#else
#error Byte order not defined
#endif
#endif
		uint8_t data[0];
};

/*! \brief  Requests a frame to be allocated 
 * 
 * \param source 
 * Request a frame be allocated.  source is an optional source of the frame, 
 * len is the requested length, or "0" if the caller will supply the buffer 
 */
#if 0 /* Unimplemented */
struct ast_frame *ast_fralloc(char *source, int len);
#endif

/*!  
 * \brief Frees a frame or list of frames
 * 
 * \param fr Frame to free, or head of list to free
 * \param cache Whether to consider this frame for frame caching
 */
void ast_frame_free(struct ast_frame *fr, int cache);

#define ast_frfree(fr) ast_frame_free(fr, 1)

/*! \brief Makes a frame independent of any static storage
 * \param fr frame to act upon
 * Take a frame, and if it's not been malloc'd, make a malloc'd copy
 * and if the data hasn't been malloced then make the
 * data malloc'd.  If you need to store frames, say for queueing, then
 * you should call this function.
 * \return Returns a frame on success, NULL on error
 * \note This function may modify the frame passed to it, so you must
 * not assume the frame will be intact after the isolated frame has
 * been produced. In other words, calling this function on a frame
 * should be the last operation you do with that frame before freeing
 * it (or exiting the block, if the frame is on the stack.)
 */
struct ast_frame *ast_frisolate(struct ast_frame *fr);

/*! \brief Copies a frame 
 * \param fr frame to copy
 * Duplicates a frame -- should only rarely be used, typically frisolate is good enough
 * \return Returns a frame on success, NULL on error
 */
struct ast_frame *ast_frdup(const struct ast_frame *fr);

void ast_swapcopy_samples(void *dst, const void *src, int samples);

/* Helpers for byteswapping native samples to/from 
   little-endian and big-endian. */
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define ast_frame_byteswap_le(fr) do { ; } while(0)
#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)
#else
#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)
#define ast_frame_byteswap_be(fr) do { ; } while(0)
#endif

/*! \brief Parse an "allow" or "deny" line in a channel or device configuration
        and update the capabilities and pref if provided.
	Video codecs are not added to codec preference lists, since we can not transcode
	\return Returns number of errors encountered during parsing
 */
int ast_parse_allow_disallow(struct ast_codec_pref *pref, struct ast_format_cap *cap, const char *list, int allowing);

/*! \name AST_Smoother 
*/
/*@{ */
/*! \page ast_smooth The AST Frame Smoother
The ast_smoother interface was designed specifically
to take frames of variant sizes and produce frames of a single expected
size, precisely what you want to do.

The basic interface is:

- Initialize with ast_smoother_new()
- Queue input frames with ast_smoother_feed()
- Get output frames with ast_smoother_read()
- when you're done, free the structure with ast_smoother_free()
- Also see ast_smoother_test_flag(), ast_smoother_set_flags(), ast_smoother_get_flags(), ast_smoother_reset()
*/
struct ast_smoother;

struct ast_smoother *ast_smoother_new(int bytes);
void ast_smoother_set_flags(struct ast_smoother *smoother, int flags);
int ast_smoother_get_flags(struct ast_smoother *smoother);
int ast_smoother_test_flag(struct ast_smoother *s, int flag);
void ast_smoother_free(struct ast_smoother *s);
void ast_smoother_reset(struct ast_smoother *s, int bytes);

/*!
 * \brief Reconfigure an existing smoother to output a different number of bytes per frame
 * \param s the smoother to reconfigure
 * \param bytes the desired number of bytes per output frame
 * \return nothing
 *
 */
void ast_smoother_reconfigure(struct ast_smoother *s, int bytes);

int __ast_smoother_feed(struct ast_smoother *s, struct ast_frame *f, int swap);
struct ast_frame *ast_smoother_read(struct ast_smoother *s);
#define ast_smoother_feed(s,f) __ast_smoother_feed(s, f, 0)
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define ast_smoother_feed_be(s,f) __ast_smoother_feed(s, f, 1)
#define ast_smoother_feed_le(s,f) __ast_smoother_feed(s, f, 0)
#else
#define ast_smoother_feed_be(s,f) __ast_smoother_feed(s, f, 0)
#define ast_smoother_feed_le(s,f) __ast_smoother_feed(s, f, 1)
#endif
/*@} Doxygen marker */

void ast_frame_dump(const char *name, struct ast_frame *f, char *prefix);

/*! \brief Returns the number of samples contained in the frame */
int ast_codec_get_samples(struct ast_frame *f);

/*! \brief Returns the number of bytes for the number of samples of the given format */
int ast_codec_get_len(struct ast_format *format, int samples);

/*! \brief Appends a frame to the end of a list of frames, truncating the maximum length of the list */
struct ast_frame *ast_frame_enqueue(struct ast_frame *head, struct ast_frame *f, int maxlen, int dupe);


/*! \brief Gets duration in ms of interpolation frame for a format */
static inline int ast_codec_interp_len(struct ast_format *format)
{ 
	return (format->id == AST_FORMAT_ILBC) ? 30 : 20;
}

/*!
  \brief Adjusts the volume of the audio samples contained in a frame.
  \param f The frame containing the samples (must be AST_FRAME_VOICE and AST_FORMAT_SLINEAR)
  \param adjustment The number of dB to adjust up or down.
  \return 0 for success, non-zero for an error
 */
int ast_frame_adjust_volume(struct ast_frame *f, int adjustment);

/*!
  \brief Sums two frames of audio samples.
  \param f1 The first frame (which will contain the result)
  \param f2 The second frame
  \return 0 for success, non-zero for an error

  The frames must be AST_FRAME_VOICE and must contain AST_FORMAT_SLINEAR samples,
  and must contain the same number of samples.
 */
int ast_frame_slinear_sum(struct ast_frame *f1, struct ast_frame *f2);

/*!
 * \brief Clear all audio samples from an ast_frame. The frame must be AST_FRAME_VOICE and AST_FORMAT_SLINEAR
 */
int ast_frame_clear(struct ast_frame *frame);

/*!
 * \brief Copy the discription of a frame's subclass into the provided string
 *
 * \param f The frame to get the information from
 * \param subclass Buffer to fill with subclass information
 * \param slen Length of subclass buffer
 * \param moreinfo Buffer to fill with additional information
 * \param mlen Length of moreinfo buffer
 * \since 11
 */
void ast_frame_subclass2str(struct ast_frame *f, char *subclass, size_t slen, char *moreinfo, size_t mlen);

/*!
 * \brief Copy the discription of a frame type into the provided string
 *
 * \param frame_type The frame type to be described
 * \param ftype Buffer to fill with frame type description
 * \param len Length of subclass buffer
 * \since 11
 */
void ast_frame_type2str(enum ast_frame_type frame_type, char *ftype, size_t len);

#if defined(__cplusplus) || defined(c_plusplus)
}
#endif

#endif /* _ASTERISK_FRAME_H */