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