Ubuntu 下QT 创建FFMpeg SDL 开发环境遇到的问题以及SDL_Init初始化失败返回-1

周六在家没什么事，就来公司加班。

最近正好在做音视频的项目，避免不了要和FFMpeg打些交道。之前没怎么接用过FFMpeg，之前就是简单的用FFmpeg拉了RTSP流，截个图缩放什么的更深入的功能没有做过。想借助这个时间好好学习下FFMpeg。本来想在windows下做的，需要下载visual studio .网上看了下 VS太大了真的太大了动不动10几个G 公司的网速下载看了下不到500K 放弃了。

正好项目开发是在ubuntu下的有VMware的ubuntu环境。我自己都不知道什么时候装了QT。

QT本来就是跨平台的，网上搜了下在Ubuntu下可以用QT+FFMpeg+SDL来做开发。

之前已经下了FFMpeg的源码了，只不过编译的是海思平台ARM版本的需要重新编译成ubuntu版本。

编译脚本如下，默认配置

./configure --prefix=./install_ubunt \
--disable-x86asm

接着 make make install 没啥问题

接下来QT新建一个NON-QT的 plain C或者C++项目都可以，修改pro配置文件

如下图

写了个测试程序编译出错更准确的应该是连接如下图莫名其妙的一大堆

没咋搞过百度，大概知道了原因

pro文件添加

LIBS += -lz 没问题继续编译

又来了连接错误如下图

这次是找不到av开头的函数，继续百度百度说要把libavformat.a放在最前面

果然放在前面就没这个错误了 FFMpeg的代码顺利执行没问题。

接下来要把SDL也集成进来。官网直接下源码http://www.libsdl.org/download-2.0.php

下下来配置下 make make install

有个比较吭的地方是 sdl的configure 不支持相对路径只能用绝对路径没办法

看这么一长串的目录都闹心，对了说下我习惯建一个build.sh 把这个配置写进去，直接执行对应的脚本，这样不同平台起一个不用的名字，比如arm平台需要修改编译链，增加删除裁剪一些功能什么的这，这样比较方便。

./configure --prefix=/home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/SDL2-2.0.16/install_ubuntu

OK 继续，改pro文件把头文件的路径，lib都加进工程里面，网上copy一个简单的测试环境

编译又是报错 SDL_SetVideoMode API什么的找不到，继续百度，百度说是这个API过期了，得用新的API好继续改改好了 ok编译又是一连串红色错误：

继续百度

说是要LIBS += -ldl ok 修改pro文件编译一切ok 运行又出错了

继续百度发现是虚拟机下AUDIO设备不正常所以失败了，SDL_Init那里去掉 AUDIO 的flag 终于运行正常了。看效果图

完整的PRO配置如下：

TEMPLATE = app
CONFIG += console c++11
CONFIG -= app_bundle
CONFIG -= qt

SOURCES += main.cpp

INCLUDEPATH +=  /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/FFmpeg-n4.3.2/install_ubunt/include
INCLUDEPATH +=  /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/SDL2-2.0.16/install_ubuntu/include

LIBS +=     /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/FFmpeg-n4.3.2/install_ubunt/lib/libavformat.a
LIBS +=     /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/FFmpeg-n4.3.2/install_ubunt/lib/libavcodec.a

LIBS +=     /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/FFmpeg-n4.3.2/install_ubunt/lib/libavdevice.a
LIBS +=     /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/FFmpeg-n4.3.2/install_ubunt/lib/libavfilter.a

LIBS +=     /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/FFmpeg-n4.3.2/install_ubunt/lib/libavutil.a
LIBS +=     /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/FFmpeg-n4.3.2/install_ubunt/lib/libswresample.a
LIBS +=     /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/FFmpeg-n4.3.2/install_ubunt/lib/libswscale.a
LIBS +=     /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/SDL2-2.0.16/install_ubuntu/lib/libSDL2.a
LIBS +=     /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/SDL2-2.0.16/install_ubuntu/lib/libSDL2main.a
LIBS +=     /home/jason/HS/Hi3531DV200_SDK_V2.0.0.3/mpp/sample/SDL2-2.0.16/install_ubuntu/lib/libSDL2_test.a

LIBS += -lpthread
LIBS += -lxcb -lm

LIBS += -lz
LIBS += -ldl

main.cpp如下：

#include <iostream>

using namespace std;


#include<stdlib.h>

#include <sys/stat.h>
#include <unistd.h>

#define RTSPSOURCE1  "rtsp://uer:[email protected]:554/Streaming/Channels/101"	//720P

extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavdevice/avdevice.h"
#include "SDL2/SDL.h"
}


void SaveFrame(AVFrame *frame,int width, int height ,int iFrame)
{
    FILE *fp;
    char filename[100]={0};
    int y = 0;

    sprintf(filename,"frame_%d.ppm",iFrame);
    fp = fopen(filename,"wb");
    if(fp == NULL)
    {
        cout<<"fp is null "<<endl;
        return;
    }

    fprintf(fp,"P6\n%d %d\n255\n",width,height);

    for(y=0;y<height;y++)
    {
        fwrite(frame->data[0]+y*frame->linesize[0],1,width*3,fp);
    }
    fclose(fp);
    cout<<"fp is end "<<endl;
}

int main()
{
    AVFormatContext *pFormatCtx = NULL;
    AVDictionary *options = NULL;
    AVPacket *packet = NULL;
    AVCodecContext* avc_cxt = NULL;
    AVFrame* frame = NULL;
    AVFrame* frameRGB = NULL;
    AVCodec* codec    ;
    struct SwsContext *sws_ctx = NULL;
    int ret = 0,i = 0;
    char *input_file = RTSPSOURCE1;
    int videoindex = -1;
    uint8_t *buffer = NULL;
    int bytes = 0;
    int gotFrame = 0;
    int w_width = 1280;
    int w_height = 720;
    Uint32 pixformat;

	SDL_Rect rect;
    SDL_Window *win = NULL;
    SDL_Renderer *renderer = NULL;
    SDL_Texture *texture = NULL;

    ret = SDL_Init(SDL_INIT_VIDEO);
    if (ret) {
		cout<<"SDL init error :"<<ret<<endl;
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Could not initialize SDL - %s\n", SDL_GetError());
        return ret;
    }


    av_dict_set(&options, "buffer_size", "1024000", 0); //Buffer size


    av_dict_set(&options, "rtsp_transport", "tcp", 0); //UDP or TCP

    av_dict_set(&options, "stimeout", "5000000", 0); //Timeout value :us
    av_dict_set(&options, "max_delay", "500000", 0); //Max delay time:us

    pFormatCtx = avformat_alloc_context(); //Init handle


    //Open file or stream URL
    ret = avformat_open_input(&pFormatCtx, input_file, NULL, &options);
    if(ret != 0)
    {
        cout<<"open file failed:"<<input_file<<endl;
    }


    //Get video info
    if (avformat_find_stream_info(pFormatCtx, NULL)<0)
    {
        printf("Couldn't find stream information.\n");

        goto EXIT;
    }

    //Check if has video info


    for (i = 0; i<pFormatCtx->nb_streams; i++)
    if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
    {
        videoindex = i;
        break;
    }
    if (videoindex == -1)
    {
        printf("Didn't find a video stream.\n");

        goto EXIT;
    }

    av_dump_format(pFormatCtx,0,input_file,0);

    avc_cxt = pFormatCtx->streams[videoindex]->codec;

    codec = avcodec_find_decoder(avc_cxt->codec_id);
    if(!codec){
        av_log(NULL,AV_LOG_ERROR,"No decoder ");
        goto EXIT;
    }
    ret = avcodec_open2(avc_cxt,codec,NULL);
    if(ret < 0){
        av_log(NULL,AV_LOG_ERROR,"Can not open decoder");
        goto EXIT;
    }

    frame = av_frame_alloc();

    frameRGB = av_frame_alloc();
    if(frameRGB == NULL)
    {
        goto EXIT;
    }

    packet = (AVPacket *)av_malloc(sizeof(AVPacket)); //Malloc packet

    bytes= avpicture_get_size(AV_PIX_FMT_RGB24,avc_cxt->width,avc_cxt->height);
    buffer = (uint8_t*)av_malloc(bytes*sizeof(uint8_t));
    avpicture_fill((AVPicture *)frameRGB,buffer,AV_PIX_FMT_RGB24,avc_cxt->width,avc_cxt->height);

    frameRGB->width = avc_cxt->width;
    frameRGB->height = avc_cxt->height;
    sws_ctx = sws_getContext(avc_cxt->width,avc_cxt->height,avc_cxt->pix_fmt,
                 frameRGB->width,frameRGB->height,AV_PIX_FMT_RGB24,SWS_BICUBIC,NULL,NULL,NULL);

    win = SDL_CreateWindow("Media Player",
                           SDL_WINDOWPOS_UNDEFINED,
                           SDL_WINDOWPOS_UNDEFINED,
                           w_width, w_height,
                           SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
    if (!win) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to create window by SDL");
        goto EXIT;
    }

    renderer = SDL_CreateRenderer(win, -1, 0);
    if (!renderer) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to create Renderer by SDL");
        goto EXIT;
    }

    pixformat = SDL_PIXELFORMAT_IYUV;//YUV\u683c\u5f0f

    texture = SDL_CreateTexture(renderer,
                                pixformat,
                                SDL_TEXTUREACCESS_STREAMING,
                                w_width,
                                w_height);



    while(1)
    {
        if (av_read_frame(pFormatCtx, packet) >= 0)
        {
                if (packet->stream_index == videoindex)
            {
                //cout<<"packet size is :"<<packet->size<<endl;
                avcodec_decode_video2(avc_cxt,frame,&gotFrame,packet);
                if(gotFrame)
                {

                    if(i++ % 25 == 0)
                    {
                        ret = sws_scale(sws_ctx, (uint8_t const * const *)frame->data,
                                frame->linesize, 0, frame->height,
                                frameRGB->data, frameRGB->linesize);
                        cout<<"ret :"<<ret<<endl;
                        SaveFrame(frameRGB,avc_cxt->width,avc_cxt->height,i);
                        if(i>200)
                        {
                            //goto EXIT;
                        }
                    }

                SDL_UpdateYUVTexture(texture, NULL,
                                     frame->data[0], frame->linesize[0],
                                     frame->data[1], frame->linesize[1],
                                     frame->data[2], frame->linesize[2]);
 
                // Set Size of Window
                rect.x = 0;
                rect.y = 0;
                rect.w = frameRGB->width;
                rect.h = frameRGB->height;
 

                SDL_RenderClear(renderer);
                SDL_RenderCopy(renderer, texture, NULL, &rect);
                SDL_RenderPresent(renderer);					

                }
                else
                {
                    cout<<"avcodec_decode_video2 failed size is:"<<packet->size<<endl;
                }
                av_frame_unref(frame);

            }
            av_packet_unref(packet);

	        SDL_Event event;
	        SDL_PollEvent(&event);
	        switch (event.type) {
	            case SDL_QUIT:
	                goto EXIT;
	            default:
	                break;
	        }			
        }

    }
	
	EXIT:

	av_free(buffer);

	av_free(packet);
	av_frame_free(&frameRGB);
	av_frame_free(&frame);
	avformat_close_input(&pFormatCtx);

	if (win) {
		SDL_DestroyWindow(win);
	}

	if (renderer) {
		SDL_DestroyRenderer(renderer);
	}

	if (texture) {
		SDL_DestroyTexture(texture);
	}

	SDL_Quit();


    printf("%s This is a test \n",__FUNCTION__);
    return 0;
}

SaveFrame是之前测试保存图片用的

前文提到SDL_Init里面有SDL_INIT_AUDIO 的时候回初始化失败返回-1

网上搜了下说要装两个东东如下：

 sudo apt-get install libasound2-dev libpulse-dev

下载完之后，SDL make clean 重新 build make make install 即可解决返回-1 的问题。

Ubuntu 下QT 创建FFMpeg SDL 开发环境遇到的问题 以及SDL_Init初始化失败返回-1

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