移植live555 上的 rtsp

一、V4L2视频采集模块（完整示例）

#include <linux/videodev2.h>
#include <sys/ioctl.h>
#include <fcntl.h>// 初始化V4L2摄像头
int init_v4l2_camera(const char* dev_path, int width, int height) {int fd = open(dev_path, O_RDWR);if (fd < 0) {perror("Failed to open V4L2 device");return -1;}// 设置视频格式（YUV422）struct v4l2_format fmt = {0};fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;fmt.fmt.pix.width = width;fmt.fmt.pix.height = height;fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV; // 海思可能要求NV12fmt.fmt.pix.field = V4L2_FIELD_NONE;if (ioctl(fd, VIDIOC_S_FMT, &fmt) < 0) {perror("Failed to set video format");close(fd);return -1;}// 申请视频缓冲区（MMAP方式）struct v4l2_requestbuffers req = {0};req.count = 4;req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;req.memory = V4L2_MEMORY_MMAP;if (ioctl(fd, VIDIOC_REQBUFS, &req) < 0) {perror("Failed to request buffers");close(fd);return -1;}// 映射缓冲区到用户空间struct v4l2_buffer buf = {0};for (int i = 0; i < req.count; ++i) {buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;buf.memory = V4L2_MEMORY_MMAP;buf.index = i;if (ioctl(fd, VIDIOC_QUERYBUF, &buf) < 0) {perror("Failed to query buffer");close(fd);return -1;}void* buffer = mmap(NULL, buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd, buf.m.offset);// 保存buffer指针...}// 启动视频流enum v4l2_buf_type type = V4L2_BUF_TYPE_VIDEO_CAPTURE;if (ioctl(fd, VIDIOC_STREAMON, &type) < 0) {perror("Failed to start streaming");close(fd);return -1;}return fd; // 返回设备句柄
}

关键点解释：

• 海思平台可能要求输入NV12格式，需根据硬件文档调整V4L2_PIX_FMT_*
• MMAP方式减少内存拷贝，适合高帧率场景
• 需循环调用VIDIOC_QBUF和VIDIOC_DQBUF获取视频帧

---

二、海思H.264硬件编码模块

#include "hi_comm_venc.h"
#include "mpi_venc.h"// 初始化海思编码通道
HI_S32 init_hisi_venc(int width, int height, int fps) {HI_S32 s32Ret;VENC_CHN VencChn = 0;VENC_ATTR_S stVencAttr;// 配置编码参数memset(&stVencAttr, 0, sizeof(VENC_ATTR_S));stVencAttr.enType = PT_H264;stVencAttr.stRcAttr.enRcMode = VENC_RC_MODE_H264CBR;stVencAttr.stRcAttr.stH264Cbr.u32Gop = fps * 2; // GOP为2秒stVencAttr.stRcAttr.stH264Cbr.u32BitRate = 2000; // 2000kbpsstVencAttr.stVencAttr.stAttrH264e.u32MaxPicWidth = width;stVencAttr.stVencAttr.stAttrH264e.u32MaxPicHeight = height;stVencAttr.stVencAttr.stAttrH264e.u32PicWidth = width;stVencAttr.stVencAttr.stAttrH264e.u32PicHeight = height;// 创建编码通道s32Ret = HI_MPI_VENC_CreateChn(VencChn, &stVencAttr);if (s32Ret != HI_SUCCESS) {printf("Create VENC channel failed: 0x%x\n", s32Ret);return s32Ret;}// 设置帧率VENC_PARAM_FRMRATE_PARA_S stFrmRate;stFrmRate.stSrcFrmRate.s32FrmRate = fps * 1000; // 以毫秒为单位stFrmRate.stDstFrmRate.s32FrmRate = fps * 1000;HI_MPI_VENC_SetFrmRate(VencChn, &stFrmRate);return HI_SUCCESS;
}// 获取编码后的H.264流
void get_h264_stream(VENC_CHN VencChn, unsigned char** ppBuffer, HI_U32* pSize) {VENC_STREAM_S stStream;HI_S32 s32Ret = HI_MPI_VENC_GetStream(VencChn, &stStream, 2000); // 2秒超时if (s32Ret == HI_SUCCESS) {*ppBuffer = stStream.pstPack[0].pu8Addr;*pSize = stStream.pstPack[0].u32Len;HI_MPI_VENC_ReleaseStream(VencChn, &stStream); // 必须释放}
}

关键点：

• 使用HI_MPI_VENC_GetStream非阻塞方式获取码流
• 必须调用HI_MPI_VENC_ReleaseStream释放资源，否则会导致内存泄漏
• 海思SDK要求严格的内存对齐，需按照文档配置参数

三、ALSA音频采集与AAC编码

#include <alsa/asoundlib.h>
#include <fdk-aac/aacenc_lib.h>// 初始化ALSA音频采集
snd_pcm_t* init_alsa(const char* device, int sample_rate, int channels) {snd_pcm_t* handle;snd_pcm_hw_params_t* params;if (snd_pcm_open(&handle, device, SND_PCM_STREAM_CAPTURE, 0) < 0) {fprintf(stderr, "ALSA open error\n");return NULL;}snd_pcm_hw_params_malloc(&params);snd_pcm_hw_params_any(handle, params);// 设置参数snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE);snd_pcm_hw_params_set_channels(handle, params, channels);snd_pcm_hw_params_set_rate_near(handle, params, (unsigned int*)&sample_rate, 0);// 应用参数if (snd_pcm_hw_params(handle, params) < 0) {fprintf(stderr, "ALSA set params failed\n");snd_pcm_close(handle);return NULL;}return handle;
}// 初始化AAC编码器
AACENCODER* init_aac_encoder(int sample_rate, int channels) {AACENCODER* hEncoder;if (aacEncOpen(&hEncoder, 0, channels) != AACENC_OK) {return NULL;}// 设置编码参数aacEncoder_SetParam(hEncoder, AACENC_AOT, AOT_AAC_LC);aacEncoder_SetParam(hEncoder, AACENC_SAMPLERATE, sample_rate);aacEncoder_SetParam(hEncoder, AACENC_CHANNELMODE, MODE_2);aacEncoder_SetParam(hEncoder, AACENC_BITRATE, 64000); // 64kbpsif (aacEncEncode(hEncoder, NULL, NULL, NULL, NULL) != AACENC_OK) {aacEncClose(&hEncoder);return NULL;}return hEncoder;
}

四、live555自定义FramedSource实现

#include <liveMedia.hh>class Hi3516VideoSource : public FramedSource {
public:static Hi3516VideoSource* createNew(UsageEnvironment& env, VENC_CHN vencChn) {return new Hi3516VideoSource(env, vencChn);}protected:Hi3516VideoSource(UsageEnvironment& env, VENC_CHN vencChn) : FramedSource(env), mVencChn(vencChn) {}virtual void doGetNextFrame() {// 从海思编码器获取H.264数据unsigned char* pData = nullptr;HI_U32 dataSize = 0;get_h264_stream(mVencChn, &pData, &dataSize);if (dataSize > 0) {if (dataSize > fMaxSize) { // 处理分包fNumTruncatedBytes = dataSize - fMaxSize;dataSize = fMaxSize;}memcpy(fTo, pData, dataSize);fFrameSize = dataSize;// 设置时间戳（使用系统时钟）gettimeofday(&fPresentationTime, NULL);} else {fFrameSize = 0;}// 立即通知框架可以发送数据afterGetting(this);}private:VENC_CHN mVencChn;
};

关键逻辑：

• doGetNextFrame()是live555的核心回调函数，当需要发送数据时自动触发
• 时间戳必须转换为RTP时间基准（视频：90000Hz，音频：采样率）
• 若数据超过缓冲区大小，需设置fNumTruncatedBytes

---

五、RTSP服务端搭建

#include "liveMedia.hh"
#include "BasicUsageEnvironment.hh"void start_rtsp_server() {TaskScheduler* scheduler = BasicTaskScheduler::createNew();UsageEnvironment* env = BasicUsageEnvironment::createNew(*scheduler);// 创建RTSP服务器（端口554需要root权限）RTSPServer* rtspServer = RTSPServer::createNew(*env, 554, NULL);if (rtspServer == NULL) {*env << "Failed to create RTSP server: " << env->getResultMsg() << "\n";exit(1);}// 创建媒体会话（H.264 + AAC）ServerMediaSession* sms = ServerMediaSession::createNew(*env, "live", "Hi3516 Live Stream", "Session for Hi3516");// 添加视频子会话sms->addSubsession(H264VideoFileServerMediaSubsession::createNew(*env, "dummy", NULL)); // 实际应使用自定义Source// 添加音频子会话（AAC）sms->addSubsession(ADTSAudioFileServerMediaSubsession::createNew(*env, "dummy", NULL));rtspServer->addServerMediaSession(sms);// 打印RTSP URLchar* url = rtspServer->rtspURL(sms);*env << "RTSP URL: " << url << "\n";delete[] url;env->taskScheduler().doEventLoop(); // 进入主循环
}

六、音视频同步策略

// 全局时间戳生成器（单位：微秒）
uint64_t get_ntp_timestamp() {struct timeval tv;gettimeofday(&tv, NULL);return (uint64_t)tv.tv_sec * 1000000 + tv.tv_usec;
}// 在FramedSource中设置时间戳
void Hi3516VideoSource::doGetNextFrame() {// ... 获取数据 ...uint64_t now = get_ntp_timestamp();fPresentationTime.tv_sec = now / 1000000;fPresentationTime.tv_usec = now % 1000000;
}// 音频同步需转换为采样数
uint32_t audio_rtp_timestamp(uint64_t ntp_ts, int sample_rate) {return (uint32_t)((ntp_ts * sample_rate) / 1000000);
}

七、完整流程整合

1. 初始化硬件模块

   int v4l2_fd = init_v4l2_camera("/dev/video0", 1280, 720);
   init_hisi_venc(1280, 720, 30);
   snd_pcm_t* audio_handle = init_alsa("default", 44100, 2);
   AACENCODER* aac_enc = init_aac_encoder(44100, 2);
   

2. 启动RTSP服务线程

   std::thread rtsp_thread(start_rtsp_server);
   rtsp_thread.detach();
   

3. 主循环采集数据

   while (1) {// 视频采集->编码->存入队列struct v4l2_buffer buf = {0};ioctl(v4l2_fd, VIDIOC_DQBUF, &buf);HI_MPI_VENC_SendFrame(vencChn, &raw_frame); // 送入编码器ioctl(v4l2_fd, VIDIOC_QBUF, &buf);// 音频采集->编码->存入队列snd_pcm_readi(audio_handle, pcm_buffer, samples);aacEncEncode(aac_enc, ...);
   }
   

八、调试技巧

1. 验证视频编码

   # 将H.264流保存为文件
   ./your_program > test.h264
   # 使用ffplay播放
   ffplay -f h264 test.h264
   

2. 分析RTSP协议

   wireshark -f "tcp port 554 or udp port range 6970-6999"
   

3. 海思SDK调试

   HI_MPI_LOG_SetLevel(LOG_LEVEL_DEBUG); // 开启海思SDK日志
   

通过以上完整实现，您可以在hi3516平台上构建稳定的RTSP音视频服务。实际部署时需根据硬件特性调整缓冲区大小、线程优先级等参数。