ffmpeg下载rtsp为mp4时，av_interleaved_write_frame这个函数崩溃原因。

    AVFormatContext *outputFormatCtx = nullptr;

    // 创建输出上下文
    avformat_alloc_output_context2(&outputFormatCtx, nullptr, "mp4", m_outputFile.toStdString().c_str());

    //记录字幕流
    int subtitleStreamIndex = -1;
    int video_stream_index = -1;
    int audio_stream_index = -1;
    // 初始化输出流索引
    int out_video_idx = -1;
    int out_audio_idx = -1;

    if(m_inFormatContext != nullptr)
    {
        //复制输入流信息
        for (int i = 0; i < m_inFormatContext->nb_streams; i++)
        {
            AVStream* inStream = m_inFormatContext->streams[i];
            AVCodecParameters* codecPar = inStream->codecpar;

            // 跳过不需要的流类型
            if (codecPar->codec_type == AVMEDIA_TYPE_SUBTITLE)
            {
                subtitleStreamIndex = i;
                continue;
            }
            else if(codecPar->codec_type == AVMEDIA_TYPE_VIDEO)
            {
                video_stream_index = i;
            }
            else if(codecPar->codec_type == AVMEDIA_TYPE_AUDIO)
            {
                audio_stream_index = i;
            }

            // 创建输出流
            AVStream* outStream = avformat_new_stream(outputFormatCtx, nullptr);
            if (!outStream) {
                qWarning() << "Failed to create output stream for stream" << i;
                continue;
            }

            // 复制编解码参数
            int ret = avcodec_parameters_copy(outStream->codecpar, codecPar);
            if (ret < 0)
            {
                qWarning() << "Failed to copy codec parameters for stream" << i;
                avformat_free_context(outputFormatCtx);
            }

            outStream->time_base = inStream->time_base;
        }
    }

    //打开输出文件
    avio_open(&outputFormatCtx->pb, m_outputFile.toStdString().c_str(), AVIO_FLAG_WRITE);
    //写输出文件头
    avformat_write_header(outputFormatCtx, nullptr);

    //确保第一帧是i帧
    bool firstKeyFrameWritten = false;
    //记录开始时间锉
    int64_t start_pts_v = AV_NOPTS_VALUE;
    int64_t start_pts_a = AV_NOPTS_VALUE;
    int64_t start_dts_v = AV_NOPTS_VALUE;
    int64_t start_dts_a = AV_NOPTS_VALUE;

    while(m_downVideoCtl == 1)
    {
        //qDebug() << "while....";
        if(m_frameQueue.isEmpty())
        {
            qDebug() << "not found pack....";
            QThread::sleep(1);
        }

        AVPacket* packet = m_frameQueue.dequeue();

        if (packet->stream_index == subtitleStreamIndex || packet->stream_index == audio_stream_index)
        {
            av_packet_free(&packet);
            continue;
        }

        // 强制第一帧必须是视频关键帧
        if (!firstKeyFrameWritten)
        {
            // 情况1: 当前包是视频关键帧 -> 允许处理
            if (packet->stream_index == video_stream_index &&
                (packet->flags & AV_PKT_FLAG_KEY))
            {
                firstKeyFrameWritten = true;
            }
            // 情况2: 其他情况 -> 丢弃包
            else {
                av_packet_free(&packet);
                continue; // 跳过所有非视频关键帧
            }
        }

        // 时间戳初始化（仅处理有效包后执行）
        if (packet->stream_index == video_stream_index) {
            if (start_pts_v == AV_NOPTS_VALUE && packet->pts != AV_NOPTS_VALUE && packet->dts != AV_NOPTS_VALUE) {
                start_pts_v = packet->pts;
                start_dts_v = packet->dts;
                qDebug() << "Video start PTS initialized:" << start_pts_v;
                qDebug() << "Video start DTS initialized:" << start_dts_v;

                // 获取视频流的 AVStream
                AVStream *video_stream = outputFormatCtx->streams[video_stream_index];
                AVRational time_base = video_stream->time_base;

                // 打印时间基（分子/分母）
                qDebug() << "Video time base:" << time_base.num << "/" << time_base.den;
            }
        }
        else if (packet->stream_index == audio_stream_index) {
            if (start_pts_a == AV_NOPTS_VALUE && packet->pts != AV_NOPTS_VALUE && packet->dts != AV_NOPTS_VALUE)
            {
                start_pts_a = packet->pts;
                start_dts_a = packet->dts;
                qDebug() << "Audio start PTS initialized:" << start_pts_a;
            }
        }

        qDebug() << "pack frame....";
        // 时间戳调整（带有效性检查）
        if (packet->pts != AV_NOPTS_VALUE) {
            if (packet->stream_index == video_stream_index && start_pts_v != AV_NOPTS_VALUE)
            {
                packet->pts -= start_pts_v;
                packet->dts -= start_dts_v;
 //                packet->dts -= start_pts_v;
            }
            else if (packet->stream_index == audio_stream_index && start_pts_a != AV_NOPTS_VALUE)
            {
                packet->pts -= start_pts_a;
                packet->dts -= start_dts_a;
 //                packet->dts -= start_pts_a;
            }
        }

        qDebug() << QString("pts:%1, dts:%2").arg(packet->pts).arg(packet->dts);
        av_interleaved_write_frame(outputFormatCtx, packet);
        qDebug() << "av_interleaved_write_frame end....";


        av_packet_free(&packet);
    }

    // 清理资源
    av_write_trailer(outputFormatCtx);
    avformat_free_context(outputFormatCtx);

av_interleaved_write_frame，这个函数使用时出现崩溃问题，后续查询发现在保存为mp4时，音频格式必须是aac格式，否者会出现崩溃问题。