FFmpeg 播放rtsp流视频

FFmpeg

ffmpeg是较成熟的一款音视频开源库，由于公司有音视频这块的开发需求，所以本人就对FFmpeg的粗浅了解做一个学习记录.

ffmpeg 播放rtsp流视频不含音频要经过如下几个步骤，打开流，查找视频流，创建解码器，打开解码器，循环读取数据，解码数据为图像数据，播放

流程如下：

Created with Raphaël 2.2.0 读取视频文件 avformat_open_input(...) 查找视频信息 avformat_find_stream_info(...) 查找解码器 avcodec_find_decode(...) 打开解码器 avcodec_open2(...) 读视频帧 av_read_frame(...) 解码视频帧 avcodec_decode_video2(...) 像素转换 sws_scale(...) 显示视频 ANativeWindow_lock(...) ANativeWindow_unlockAndPost(...) End

---

函数调用过程中返回的错误代码可用如下代码解析出来:

char temp[30] = {0};
av_strerror(ret,temp,30);

---

视频播放代码：

 //-------------------------相关变量初始化-------------------//
    int ret = 0,i = 0;
    int videoStream = -1;
    AVPacket *pPacket;
    AVFrame *pFrame;
    int got_picture;
    mFlagStop = false;
    mFlayPause = false;
    //-----------------------------必须有，初始化工作-------------//
    av_register_all();
    avformat_network_init();

    LOGD("inputUrl = %s",inputUrl);
    m_iformatCtx = avformat_alloc_context();
    ret = avformat_open_input(&m_iformatCtx,inputUrl,NULL,NULL);
    if(ret <0){
        char temp[30] = {0};
        av_strerror(ret,temp,30);
        LOGE("open inpput fail! %d - %s",ret,temp);
        return;
    }
    ret = avformat_find_stream_info(m_iformatCtx,NULL);
    if(ret<0){
        LOGE("Couldn't find stream info !");
        goto error;
    }
    videoStream = -1;
    for(i = 0;inb_streams;i++){
        if(m_iformatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO){
            videoStream = i;
            break;
        }
    }
    if(videoStream == -1){
        LOGE("Didn't find video stream !");
        goto error;
    }
    m_icondecCtx = m_iformatCtx->streams[videoStream]->codec;
    //-------------------------------查找解码器--------------------------//
    m_icodec = avcodec_find_decoder(m_icondecCtx->codec_id);
    if(!m_icodec){
        LOGE("Codec not find !");
        goto error;
    }
    //-------------------------------打开解码器--------------------------//
    ret = avcodec_open2(m_icondecCtx,m_icodec,NULL);
    if(ret <0){
        LOGE("codec open fail!");
        goto error;
    }

    if ((m_icondecCtx->width > 0) && (m_icondecCtx->height > 0)) {
        set_BuffersGeometry(m_icondecCtx->width,
                            m_icondecCtx->height);
    }
    pPacket = av_packet_alloc();
    av_init_packet(pPacket);
    pFrame = av_frame_alloc();
    while(!mFlagStop){
        ret = av_read_frame(m_iformatCtx,pPacket);
        if(ret <0){
            LOGE("read error!");
            break;
        }
        ret = avcodec_decode_video2(m_icondecCtx,pFrame,&got_picture,pPacket);
        if(got_picture == 1){
            uint8_t *dst_data[8];
            int dst_linesize[8];
            av_image_alloc(dst_data,dst_linesize,m_icondecCtx->width,m_icondecCtx->height,
                           AV_PIX_FMT_RGB565LE,16);
            img_convert(dst_data,dst_linesize, AV_PIX_FMT_RGB565LE, (AVPicture *) pFrame,
                        m_icondecCtx->pix_fmt,
                        m_icondecCtx->width,
                        m_icondecCtx->height);
            render_surface(dst_data[0]);
            av_freep(dst_data);
        }
    }
    error:
    if(m_icondecCtx){
        avcodec_close(m_icondecCtx);
        m_icondecCtx = NULL;
    }
    if(m_iformatCtx){
        avformat_close_input(&m_iformatCtx);
        m_iformatCtx = NULL;
    }
    avformat_network_deinit();

---

render_surface方法是视频渲染的代码，代码如下

/**
 * 渲染surface
 * @param pixel
 */
void render_surface(uint8_t *pixel) {
    LOGV("MonkeyDemo:  renderSurface");
    if (mFlayPause) {
        return;
    }

    ANativeWindow_acquire(mANativeWindow);
//    LOGV("开始渲染");
    if (0 != ANativeWindow_lock(mANativeWindow, &nwBuffer, NULL)) {
        LOGV("ANativeWindow_lock() error");
        return;
    }
    //LOGV("renderSurface, %d, %d, %d", nwBuffer.width ,nwBuffer.height, nwBuffer.stride);
    if (nwBuffer.width >= nwBuffer.stride) {
        //srand(time(NULL));
        //memset(piexels, rand() % 100, nwBuffer.width * nwBuffer.height * 2);
        //memcpy(nwBuffer.bits, piexels, nwBuffer.width * nwBuffer.height * 2);
        memcpy(nwBuffer.bits, pixel, nwBuffer.width * nwBuffer.height * 2);
    } else {
//        LOGV("new buffer width is %d,height is %d ,stride is %d",
//             nwBuffer.width, nwBuffer.height, nwBuffer.stride);
        int i;
        for (i = 0; i < nwBuffer.height; ++i) {
            memcpy((void*) ((uintptr_t) nwBuffer.bits + nwBuffer.stride * i * 2),
                   (void*) ((uintptr_t) pixel + nwBuffer.width * i * 2),
                   nwBuffer.width * 2);
        }
    }

    if (0 != ANativeWindow_unlockAndPost(mANativeWindow)) {
        LOGV("ANativeWindow_unlockAndPost error");
        return;
    }

    ANativeWindow_release(mANativeWindow);
}

img_convert是格式转换的方法,将AVFrame结构体对应的图像数据转换为指定格式的图像数据

/**
 * 格式转换
 * @param dst_data
 * @param dst_linesize
 * @param dst_pix_fmt
 * @param src
 * @param src_pix_fmt
 * @param src_width
 * @param src_height
 * @return
 */
int img_convert(uint8_t *dst_data[8],int dst_linesize[8], int dst_pix_fmt, const AVPicture *src,
                int src_pix_fmt, int src_width, int src_height) {
    int w;
    int h;
    struct SwsContext *pSwsCtx;

    w = src_width;
    h = src_height;

    pSwsCtx = sws_getContext(w, h, (AVPixelFormat) src_pix_fmt, w, h,
                             (AVPixelFormat) dst_pix_fmt, SWS_BICUBIC, NULL, NULL, NULL);
    sws_scale(pSwsCtx, (const uint8_t *const *) src->data, src->linesize, 0, h,
              dst_data, dst_linesize);
    sws_freeContext(pSwsCtx);
    return 0;
}

源码地址