D-Modem/pjproject-2.11.1/pjmedia/include/pjmedia-codec/passthrough.h
2021-10-29 14:41:03 -04:00

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C

/* $Id$ */
/*
* Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
* Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __PJMEDIA_CODECS_PASSTHROUGH_H__
#define __PJMEDIA_CODECS_PASSTHROUGH_H__
/**
* @file pjmedia-codec/passthrough.h
* @brief Passthrough codecs.
*/
#include <pjmedia-codec/types.h>
/**
* @defgroup PJMED_PASSTHROUGH_CODEC Passthrough Codecs
* @ingroup PJMEDIA_CODEC_CODECS
* @brief Implementation of passthrough codecs
* @{
*
* This section describes functions to initialize and register passthrough
* codecs factory to the codec manager. After the codec factory has been
* registered, application can use @ref PJMEDIA_CODEC API to manipulate
* the codec.
*
* Passthrough codecs are codecs wrapper that does NOT perform encoding
* or decoding, it just PACK and PARSE encoded audio data from/into RTP
* payload. This will accomodate pjmedia ports which work with encoded
* audio data, e.g: encoded audio files, sound device with capability
* of playing/recording encoded audio data.
*
* This codec factory contains various codecs, i.e: G.729, iLBC,
* AMR, and G.711.
*
*
* \section pjmedia_codec_passthrough_g729 Passthrough G.729
*
* G.729 supports 16-bit PCM audio signal with sampling rate 8000Hz,
* frame length 10ms, and resulting in bitrate 8000bps.
*
* \subsection codec_setting Codec Settings
*
* General codec settings for this codec such as VAD and PLC can be
* manipulated through the <tt>setting</tt> field in #pjmedia_codec_param.
* Please see the documentation of #pjmedia_codec_param for more info.
*
* Note that G.729 VAD status should be signalled in SDP, see more
* description below.
*
* \subsubsection annexb Annex B
*
* The capability of VAD/DTX is specified in Annex B.
*
* By default, Annex B is enabled. This default setting of Annex B can
* be modified using #pjmedia_codec_mgr_set_default_param().
*
* In #pjmedia_codec_param, Annex B is configured via VAD setting and
* format parameter "annexb" in the SDP "a=fmtp" attribute in
* decoding fmtp field. Valid values are "yes" and "no",
* the implementation default is "yes". When this parameter is omitted
* in the SDP, the value will be "yes" (RFC 4856 Section 2.1.9).
*
* Here is an example of modifying default setting of Annex B to
* be disabled using #pjmedia_codec_mgr_set_default_param():
\code
pjmedia_codec_param param;
pjmedia_codec_mgr_get_default_param(.., &param);
...
// Set VAD
param.setting.vad = 0;
// Set SDP format parameter
param.setting.dec_fmtp.cnt = 1;
param.setting.dec_fmtp.param[0].name = pj_str("annexb");
param.setting.dec_fmtp.param[0].val = pj_str("no");
...
pjmedia_codec_mgr_set_default_param(.., &param);
\endcode
*
* \note
* The difference of Annex B status in SDP offer/answer may be considered as
* incompatible codec in SDP negotiation.
*
*
* \section pjmedia_codec_passthrough_ilbc Passthrough iLBC
*
* The iLBC codec is developed by Global IP Solutions (GIPS), formerly
* Global IP Sound. The iLBC offers low bitrate and graceful audio quality
* degradation on frame losses.
*
* The iLBC codec supports 16-bit PCM audio signal with sampling rate of
* 8000Hz operating at two modes: 20ms and 30ms frame length modes, resulting
* in bitrates of 15.2kbps for 20ms mode and 13.33kbps for 30ms mode.
*
* \subsection codec_setting Codec Settings
*
* General codec settings for this codec such as VAD and PLC can be
* manipulated through the <tt>setting</tt> field in #pjmedia_codec_param.
* Please see the documentation of #pjmedia_codec_param for more info.
*
* \subsubsection mode Mode
*
* The default mode should be set upon initialization, see
* #pjmedia_codec_passthrough_init2(). After the codec is initialized, the
* default mode can be modified using #pjmedia_codec_mgr_set_default_param().
*
* In #pjmedia_codec_param, iLBC mode can be set by specifying SDP
* format parameter "mode" in the SDP "a=fmtp" attribute for decoding
* direction. Valid values are "20" and "30" (for 20ms and 30ms mode
* respectively).
*
* Here is an example to set up #pjmedia_codec_param to use mode 20ms:
* \code
pjmedia_codec_param param;
...
// setting iLBC mode in SDP
param.setting.dec_fmtp.cnt = 1;
param.setting.dec_fmtp.param[0].name = pj_str("mode");
param.setting.dec_fmtp.param[0].val = pj_str("20");
...
\endcode
*
*
* \section pjmedia_codec_passthrough_amr Passthrough AMR
*
* IPP AMR supports 16-bit PCM audio signal with sampling rate 8000Hz,
* 20ms frame length and producing various bitrates that ranges from 4.75kbps
* to 12.2kbps.
*
* \subsection codec_setting Codec Settings
*
* General codec settings for this codec such as VAD and PLC can be
* manipulated through the <tt>setting</tt> field in #pjmedia_codec_param.
* Please see the documentation of #pjmedia_codec_param for more info.
*
* \subsubsection bitrate Bitrate
*
* By default, encoding bitrate is 7400bps. This default setting can be
* modified using #pjmedia_codec_mgr_set_default_param() by specifying
* prefered AMR bitrate in field <tt>info::avg_bps</tt> of
* #pjmedia_codec_param. Valid bitrates could be seen in
* #pjmedia_codec_amrnb_bitrates.
*
* \subsubsection payload_format Payload Format
*
* There are two AMR payload format types, bandwidth-efficient and
* octet-aligned. Default setting is using octet-aligned. This default payload
* format can be modified using #pjmedia_codec_mgr_set_default_param().
*
* In #pjmedia_codec_param, payload format can be set by specifying SDP
* format parameters "octet-align" in the SDP "a=fmtp" attribute for
* decoding direction. Valid values are "0" (for bandwidth efficient mode)
* and "1" (for octet-aligned mode).
*
* \subsubsection mode_set Mode-Set
*
* Mode-set is used for restricting AMR modes in decoding direction.
*
* By default, no mode-set restriction applied. This default setting can be
* be modified using #pjmedia_codec_mgr_set_default_param().
*
* In #pjmedia_codec_param, mode-set could be specified via format parameters
* "mode-set" in the SDP "a=fmtp" attribute for decoding direction. Valid
* value is a comma separated list of modes from the set 0 - 7, e.g:
* "4,5,6,7". When this parameter is omitted, no mode-set restrictions applied.
*
* Here is an example of modifying AMR default codec param:
\code
pjmedia_codec_param param;
pjmedia_codec_mgr_get_default_param(.., &param);
...
// set default encoding bitrate to the highest 12.2kbps
param.info.avg_bps = 12200;
// restrict decoding bitrate to 10.2kbps and 12.2kbps only
param.setting.dec_fmtp.param[0].name = pj_str("mode-set");
param.setting.dec_fmtp.param[0].val = pj_str("6,7");
// also set to use bandwidth-efficient payload format
param.setting.dec_fmtp.param[1].name = pj_str("octet-align");
param.setting.dec_fmtp.param[1].val = pj_str("0");
param.setting.dec_fmtp.cnt = 2;
...
pjmedia_codec_mgr_set_default_param(.., &param);
\endcode
*
*
* \section pjmedia_codec_passthrough_g711 Passthrough G.711
*
* The G.711 is an ultra low complexity codecs and in trade-off it results
* in high bitrate, i.e: 64kbps for 16-bit PCM with sampling rate 8000Hz.
*
* The factory contains two main compression algorithms, PCMU/u-Law and
* PCMA/A-Law.
*
* \subsection codec_setting Codec Settings
*
* General codec settings for this codec such as VAD and PLC can be
* manipulated through the <tt>setting</tt> field in #pjmedia_codec_param.
* Please see the documentation of #pjmedia_codec_param for more info.
*/
PJ_BEGIN_DECL
/**
* Codec passthrough configuration settings.
*/
typedef struct pjmedia_codec_passthrough_setting
{
unsigned fmt_cnt; /**< Number of encoding formats
to be enabled. */
pjmedia_format *fmts; /**< Encoding formats to be
enabled. */
unsigned ilbc_mode; /**< iLBC default mode. */
} pjmedia_codec_passthrough_setting;
/**
* Initialize and register passthrough codecs factory to pjmedia endpoint,
* all supported encoding formats will be enabled.
*
* @param endpt The pjmedia endpoint.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_codec_passthrough_init( pjmedia_endpt *endpt );
/**
* Initialize and register passthrough codecs factory to pjmedia endpoint
* with only specified encoding formats enabled.
*
* @param endpt The pjmedia endpoint.
* @param setting The settings.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_codec_passthrough_init2(
pjmedia_endpt *endpt,
const pjmedia_codec_passthrough_setting *setting);
/**
* Unregister passthrough codecs factory from pjmedia endpoint.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_codec_passthrough_deinit(void);
PJ_END_DECL
/**
* @}
*/
#endif /* __PJMEDIA_CODECS_PASSTHROUGH_H__ */