ZLMediaKit/src/Rtsp/RtspMuxer.cpp

/*
 * Copyright (c) 2016 The ZLMediaKit project authors. All Rights Reserved.
 *
 * This file is part of ZLMediaKit(https://github.com/xia-chu/ZLMediaKit).
 *
 * Use of this source code is governed by MIT license that can be found in the
 * LICENSE file in the root of the source tree. All contributing project authors
 * may be found in the AUTHORS file in the root of the source tree.
 */

#include "RtspMuxer.h"
#include "Extension/Factory.h"

namespace mediakit {

void RtspMuxer::onRtp(RtpPacket::Ptr in, bool is_key) {
    if (_rtp_stamp[in->type] != in->getHeader()->stamp) {
        //rtp时间戳变化才计算ntp，节省cpu资源
        int64_t stamp_ms = in->getStamp() * uint64_t(1000) / in->sample_rate;
        int64_t stamp_ms_inc;
        //求rtp时间戳增量
        _stamp[in->type].revise(stamp_ms, stamp_ms, stamp_ms_inc, stamp_ms_inc);
        _rtp_stamp[in->type] = in->getHeader()->stamp;
        _ntp_stamp[in->type] = stamp_ms_inc + _ntp_stamp_start;
    }

    //rtp拦截入口，此处统一赋值ntp
    in->ntp_stamp = _ntp_stamp[in->type];
    _rtpRing->write(std::move(in), is_key);
}

RtspMuxer::RtspMuxer(const TitleSdp::Ptr &title) {
    if (!title) {
        _sdp = std::make_shared<TitleSdp>()->getSdp();
    } else {
        _sdp = title->getSdp();
    }
    _rtpRing = std::make_shared<RtpRing::RingType>();
    _rtpInterceptor = std::make_shared<RtpRing::RingType>();
    _rtpInterceptor->setDelegate(std::make_shared<RingDelegateHelper>([this](RtpPacket::Ptr in, bool is_key) {
        onRtp(std::move(in), is_key);
    }));
    _ntp_stamp_start = getCurrentMillisecond(true);
}

void RtspMuxer::addTrack(const Track::Ptr &track) {
    //根据track生成sdp
    Sdp::Ptr sdp = track->getSdp();
    if (!sdp) {
        return;
    }

    auto &encoder = _encoder[track->getTrackType()];
    encoder = Factory::getRtpEncoderBySdp(sdp);
    if (!encoder) {
        return;
    }

    //设置rtp输出环形缓存
    encoder->setRtpRing(_rtpInterceptor);

    //添加其sdp
    _sdp.append(sdp->getSdp());
    trySyncTrack();
}

void RtspMuxer::trySyncTrack() {
    if (_encoder[TrackAudio] && _encoder[TrackVideo]) {
        //音频时间戳同步于视频，因为音频时间戳被修改后不影响播放
        _stamp[TrackAudio].syncTo(_stamp[TrackVideo]);
    }
}

void RtspMuxer::inputFrame(const Frame::Ptr &frame) {
    auto &encoder = _encoder[frame->getTrackType()];
    if (encoder) {
        encoder->inputFrame(frame);
    }
}

string RtspMuxer::getSdp() {
    return _sdp;
}

RtpRing::RingType::Ptr RtspMuxer::getRtpRing() const {
    return _rtpRing;
}

void RtspMuxer::resetTracks() {
    _sdp.clear();
    for (auto &encoder : _encoder) {
        encoder = nullptr;
    }
}


} /* namespace mediakit */