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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set et sw=2 ts=2: */
/***************************************************************************
* rtp_profile_opus.cc
*
* Tue Sep 10 13:53:24 CEST 2013
* Copyright 2013 Bent Bisballe Nyeng
* deva@aasimon.org
****************************************************************************/
/*
* This file is part of lrtp.
*
* lrtp is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* lrtp 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with lrtp; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Part of this code is an adaptation of the GStreamer RTP profile code for Celt
* by Wim Taymans <wim.taymans@gmail.com>
* The original code can be found in the gst-plugins-good package version 1.1.3:
* http://gstreamer.freedesktop.org/src/gst-plugins-good
*/
#include "rtp_profile_opus.h"
/*
+--------------+----------------+-----------+----------+
| Abbreviation | Name | Bandwidth | Sampling |
+--------------+----------------+-----------+----------+
| nb | Narrowband | 0 - 4000 | 8000 |
| | | | |
| mb | Mediumband | 0 - 6000 | 12000 |
| | | | |
| wb | Wideband | 0 - 8000 | 16000 |
| | | | |
| swb | Super-wideband | 0 - 12000 | 24000 |
| | | | |
| fb | Fullband | 0 - 20000 | 48000 |
+--------------+----------------+-----------+----------+
Audio bandwidth naming
Table 1
*/
/*
Recommended Bitrate
For a frame size of 20 ms, these are the bitrate "sweet spots" for
Opus in various configurations:
o 8-12 kb/s for NB speech,
o 16-20 kb/s for WB speech,
o 28-40 kb/s for FB speech,
o 48-64 kb/s for FB mono music, and
o 64-128 kb/s for FB stereo music.
*/
/*
Forward Error Correction (FEC)
The voice mode of Opus allows for "in-band" forward error correction
(FEC) data to be embedded into the bit stream of Opus.
*/
/*
RTP Header Usage
The format of the RTP header is specified in [RFC3550]. The Opus
payload format uses the fields of the RTP header consistent with this
specification.
The payload length of Opus is a multiple number of octets and
therefore no padding is required. The payload MAY be padded by an
integer number of octets according to [RFC3550].
The marker bit (M) of the RTP header is used in accordance with
Section 4.1 of [RFC3551].
The RTP payload type for Opus has not been assigned statically and is
expected to be assigned dynamically.
The receiving side MUST be prepared to receive duplicates of RTP
packets. Only one of those payloads MUST be provided to the Opus
decoder for decoding and others MUST be discarded.
Opus supports 5 different audio bandwidths which may be adjusted
during the duration of a call. The RTP timestamp clock frequency is
defined as the highest supported sampling frequency of Opus, i.e.
48000 Hz, for all modes and sampling rates of Opus. The unit for the
timestamp is samples per single (mono) channel. The RTP timestamp
corresponds to the sample time of the first encoded sample in the
encoded frame. For sampling rates lower than 48000 Hz the number of
samples has to be multiplied with a multiplier according to Table 2
to determine the RTP timestamp.
+---------+------------+
| fs (Hz) | Multiplier |
+---------+------------+
| 8000 | 6 |
| | |
| 12000 | 4 |
| | |
| 16000 | 3 |
| | |
| 24000 | 2 |
| | |
| 48000 | 1 |
+---------+------------+
Table 2: Timestamp multiplier
*/
#include "rtp_profile.h"
#include <stdio.h>
#include <string.h>
struct lrtp_profile_opus_t {
struct lrtp_profile_t profile; // 'Inherit' lrtp_profile_t
};
int profile_opus_pack(struct lrtp_profile_t *profile,
const char *frame, size_t framesize,
RTP &rtp)
{
//struct lrtp_profile_opus_t *p = (struct lrtp_profile_opus_t *)profile;
(void)profile;
rtp.setPayload(frame, framesize);
rtp.setValid(true);
return framesize;
}
int profile_opus_unpack(struct lrtp_profile_t *profile,
const RTP &rtp,
oframelist_t &framelist)
{
//struct lrtp_profile_opus_t *p = (struct lrtp_profile_opus_t *)profile;
outputframe_t *of = new outputframe_t();
of->size = rtp.payloadSize();
char *buf = (char*)malloc(of->size);
of->size = rtp.payload(buf, of->size);
of->data = buf;
of->ts = rtp.timestamp();
framelist.push_back(of);
return 0;
}
void profile_opus_destroy(struct lrtp_profile_t *profile)
{
struct lrtp_profile_opus_t *p = (struct lrtp_profile_opus_t *)profile;
delete p;
}
struct lrtp_profile_t *profile_opus_create(struct lrtp_t *lrtp,
unsigned int csrc,
va_list vp)
{
struct lrtp_profile_opus_t *p = new struct lrtp_profile_opus_t;
p->profile.pack = profile_opus_pack;
p->profile.unpack = profile_opus_unpack;
p->profile.destroy = profile_opus_destroy;
while(true) {
int type = va_arg(vp, int);
if(type == OPTION_END) break;
switch(type) {
default:
// TODO: Unknown arg type
break;
}
}
return &p->profile;
}
|
