PayloadAPP/Src/Video/ffmpegpushstream.cpp

#include "ffmpegpushstream.h"

FFmpegPushStream::FFmpegPushStream(QObject *parent) : QObject{parent} {}

/**
 * @brief 设置推流地址
 * @param url 远端推流地址
 */
void FFmpegPushStream::setRemoteIP(QString url) { pushStreamIP = url; }

int FFmpegPushStream::openNetworkStream(AVFormatContext *inputFormatCtx) {
  if (pushStreamIP.isEmpty())
    return -1;

  if (!inputFormatCtx)
    return -1;

  int ret;
  // 初始化网络输出流
  // const char *output_url = "rtsp://182.92.130.23/app/stream999";
  ret = avformat_alloc_output_context2(&outputFormatCtx, NULL, "flv",
                                       pushStreamIP.toUtf8().constData());
  if (ret < 0) {
    qDebug() << "Could not create output context.";
    return -1;
  }
  // 复制流信息
  for (unsigned int i = 0; i < inputFormatCtx->nb_streams; ++i) {
    if (inputFormatCtx->streams[i]->codecpar->codec_type ==
        AVMEDIA_TYPE_VIDEO) {
      AVStream *inputStream = inputFormatCtx->streams[i];
      AVStream *outputStream = avformat_new_stream(outputFormatCtx, nullptr);
      if (!outputStream) {
        qDebug() << "Failed allocating output stream.\n";
        return -1;
      }
      // 复制编解码器参数
      ret = avcodec_parameters_copy(outputStream->codecpar,
                                    inputStream->codecpar);
      if (ret < 0) {
        // free();
        qWarning() << "avcodec_parameters_from_context Failed";
        return -1;
      }
      // outputStream->codecpar = inputStream->codecpar;
      outputStream->codecpar->codec_tag = 0;
      // outputStream->time_base.num = 1;
      break;
    }
  }

  // 打开输出文件
  if (!(outputFormatCtx->flags & AVFMT_NOFILE)) {
    if (avio_open(&outputFormatCtx->pb, pushStreamIP.toUtf8().constData(),
                  AVIO_FLAG_WRITE) < 0) {
      qDebug() << "Could not open output file.\n";
      return -1;
    }
  }

  // 写入头文件
  ret = avformat_write_header(outputFormatCtx, NULL);
  if (ret < 0) {
    qDebug() << "Error occurred when write_header into output file.\n";
    return -1;
  }
  mInitStatus = true;
  this->inputFormatCtx = inputFormatCtx;
  startTime = av_gettime_relative();
  return 1;
}

/**
 * @brief 推流
 * @param pkt: 未解码帧
 * @param frm_cnt: 帧计数
 * @param startTime: 开始推流的时间
 * @param firstDts: 第一帧的dts
 * @return
 */
int FFmpegPushStream::pushStream(AVPacket *pkt, int frm_cnt, int64_t startTime,
                                 int64_t firstDts) {
  if (!mInitStatus)
    return -1;

  if (pkt->dts <= 0)
    return -1;
  // qDebug() << "******推流" << QString::number(frm_cnt++);
  int inputStreamIndex = pkt->stream_index;
  int outputStreamIndex = 0;
  // 没有pts的视频数据，如未解码的H.264裸流，需要重新计算其pts。
  if (pkt->pts == AV_NOPTS_VALUE) {
    AVRational time_base = inputFormatCtx->streams[inputStreamIndex]->time_base;
    // Duration between 2 frames (us)
    int64_t calc_duration =
        (double)AV_TIME_BASE /
        av_q2d(inputFormatCtx->streams[inputStreamIndex]->r_frame_rate);
    // Reset Parameters
    pkt->pts = (double)(frm_cnt * calc_duration) /
               (double)(av_q2d(time_base) * AV_TIME_BASE);
    pkt->dts = pkt->pts;
    pkt->duration =
        (double)calc_duration / (double)(av_q2d(time_base) * AV_TIME_BASE);
  }

  // 视频帧推送速度
  firstDts = av_rescale_q(firstDts,
                          inputFormatCtx->streams[inputStreamIndex]->time_base,
                          AVRational{1, AV_TIME_BASE});
  auto pts_time = av_rescale_q(
      pkt->dts, inputFormatCtx->streams[inputStreamIndex]->time_base,
      AVRational{1, AV_TIME_BASE});
  int64_t streamTime = pts_time - firstDts; // 计算帧的相对时间
  auto now_time = av_gettime() - startTime; // 获取差值
  int64_t delay = streamTime - now_time;
  if (delay > 0) {
    // qDebug() << "****************sleep time:" << QString::number(delay /
    // 1000);
    av_usleep(delay);
  }

  // 计算延时后，重新指定时间戳
  AVRational istream_base =
      inputFormatCtx->streams[inputStreamIndex]->time_base;
  AVRational ostream_base =
      outputFormatCtx->streams[outputStreamIndex]->time_base;
  pkt->pts =
      av_rescale_q_rnd(pkt->pts, istream_base, ostream_base,
                       (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
  pkt->dts =
      av_rescale_q_rnd(pkt->dts, istream_base, ostream_base,
                       (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
  pkt->pts = pkt->pts < 0 ? 0 : pkt->pts;
  pkt->dts = pkt->dts < 0 ? 0 : pkt->dts;
  pkt->duration =
      (int64_t)av_rescale_q(pkt->duration, istream_base, ostream_base);
  pkt->pos = -1;
  if (pkt->pts < pkt->dts) {
    return 1;
  }

  // 向推流服务器推送流数据
  pkt->stream_index = 0;
  int ret = av_interleaved_write_frame(outputFormatCtx, pkt);
  if (ret < 0) {
    return ret;
  }
  // 数据包写入成功，现在可以释放pkt
  av_packet_unref(pkt);
  av_packet_free(&pkt);
  return 1;
}

/**
 * @brief 停止推流
 */
void FFmpegPushStream::stopPush() {
  av_write_trailer(outputFormatCtx);
  // 关闭输出
  if (outputFormatCtx && !(outputFormatCtx->flags & AVFMT_NOFILE)) {
    avio_close(outputFormatCtx->pb);
  }
  if (outputFormatCtx) {
    avformat_free_context(outputFormatCtx);
    outputFormatCtx = nullptr;
  }
  mInitStatus = false;
}