Linux下ffmpeg庫(kù)開(kāi)發(fā)之讀取攝像頭數(shù)據(jù)

?FFmpeg是一套可以用來(lái)記錄、轉(zhuǎn)換數(shù)字音頻、視頻，并能將其轉(zhuǎn)化為流的開(kāi)源計(jì)算機(jī)程序。采用LGPL或GPL許可證。它提供了錄制、轉(zhuǎn)換以及流化音視頻的完整解決方案。它包含了非常先進(jìn)的音頻/視頻編解碼庫(kù)libavcodec，為了保證高可移植性和編解碼質(zhì)量，libavcodec里很多code都是從頭開(kāi)發(fā)的。

1.ffmpeg源碼安裝

??安裝ffmpeg庫(kù)之前需要先安裝yasm庫(kù)和x264庫(kù)。

?1.1 Yasm安裝

??下載地址：http://yasm.tortall.net/

??安裝yasm

#解壓
tar xvf /mnt/hgfs/ubuntu/software_pack/yasm-1.3.0.tar.gz  
#配置信息，生成Makefile
./configure 
#編譯安裝
make && make install 

?1.2 x264安裝

??下載地址：https://www.videolan.org/developers/x264.html

??安裝x264

#解壓
tar xvf /mnt/hgfs/ubuntu/software_pack/x264-master.tar.bz2
#配置信息，生成Makefile
./configure --prefix=$PWD/_install --enable-shared --enable-static

??若配置時(shí)提示找不到nasm則下載nasm
??安裝nasm
??nasm下載地址：https://www.nasm.us/pub/nasm/releasebuilds/2.15.03/

?Netwide Assembler （簡(jiǎn)稱 NASM）是一款基于x86架構(gòu)的匯編與反匯編軟件。它可以用來(lái)編寫(xiě)16位（8086、80286等）、32位（IA-32）和64位（x86_64）的程序。 NASM被認(rèn)為是Linux平臺(tái)上最受歡迎的匯編工具之一。
NASM可以輸出包括通用對(duì)象文件格式（COFF）、OMF（Relocatable Object Module Format，用于80x86系列處理器上）、a.out、可執(zhí)行與可鏈接格式（ELF）、Mach-O、二進(jìn)制文件（.bin，二進(jìn)制磁盤(pán)映像，用于編譯操作系統(tǒng)）等多種二進(jìn)制格式，而地址無(wú)關(guān)代碼僅支持ELF對(duì)象文件。 NASM也有自己的稱為RDOFF（Relocatable Dynamic Object File Format）的二進(jìn)制格式。

tar xvf /mnt/hgfs/ubuntu/software_pack/nasm-2.15.03.tar.gz
./autogen.sh 
./configure
make && make install

?再重新編譯x264，按照1.2小結(jié)操作：

#解壓
tar xvf /mnt/hgfs/ubuntu/software_pack/x264-master.tar.bz2
#配置信息，生成Makefile
./configure --prefix=$PWD/_install --enable-shared --enable-static
make && make install

??拷貝相關(guān)庫(kù)到系統(tǒng)目錄下

[wbyq@wbyq _install]$ sudo cp ./lib/*.so* /usr/lib -fdv

?1.3 ffmpeg安裝

??為了保證后續(xù)音視頻錄制正常，需要先安裝聲卡驅(qū)動(dòng)。

sudo apt-get install libasound2-dev

??下載地址：http://www.ffmpeg.org/download.html

?編譯安裝ffmpeg

#解壓
tar xvf /mnt/hgfs/ubuntu/software_pack/ffmpeg-4.2.5.tar.bz2
#配置信息，生成Makefile
./configure --enable-static --enable-shared --prefix=$PWD/_install --extra-cflags=-I/home/wbyq/src_pack/x264-master/_install/include --extra-ldflags=-L/home/wbyq/src_pack/x264-master/_install/lib --enable-ffmpeg --enable-libx264 --enable-gpl
#編譯安裝
make && make install

?拷貝相關(guān)庫(kù)到系統(tǒng)目錄下

[wbyq@wbyq _install]$ sudo  cp ./bin/ffmpeg /usr/bin/
[wbyq@wbyq _install]$ sudo cp lib/*.so* /usr/lib -rfdv

2. 查看ffmpeg版本信息

[wbyq@wbyq ~]$ ffmpeg -version
ffmpeg version 4.2.5 Copyright (c) 2000-2021 the FFmpeg developers
built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
configuration: --enable-static --enable-shared --prefix=/home/wbyq/src_pack/ffmpeg-4.2.5/_install --extra-cflags=-I/home/wbyq/src_pack/x264-master/_install/include --extra-ldflags=-L/home/wbyq/src_pack/x264-master/_install/lib --enable-ffmpeg --enable-libx264 --enable-gpl
libavutil      56. 31.100 / 56. 31.100
libavcodec     58. 54.100 / 58. 54.100
libavformat    58. 29.100 / 58. 29.100
libavdevice    58.  8.100 / 58.  8.100
libavfilter     7. 57.100 /  7. 57.100
libswscale      5.  5.100 /  5.  5.100
libswresample   3.  5.100 /  3.  5.100
libpostproc    55.  5.100 / 55.  5.100

3.ffmpeg代碼開(kāi)發(fā)讀取攝像頭數(shù)據(jù)通過(guò)SDL顯示

?3.1 參考代碼

#include 
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define VIDEO_DEV "/dev/video2"
pthread_mutex_t fastmutex = PTHREAD_MUTEX_INITIALIZER;//互斥鎖
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;//條件變量
typedef enum
{
	false=0,
	true,
}bool;
int width;
int height;
int size;
unsigned char *rgb_buff=NULL;
unsigned char video_flag=1;
void *Video_CollectImage(void *arg);
int main()
{
	/*創(chuàng)建攝像頭采集線程*/
	pthread_t pthid;
    pthread_create(&pthid,NULL,Video_CollectImage, NULL);
	pthread_detach(pthid);/*設(shè)置分離屬性*/
	sleep(1);
	while(1)
	{
		if(width!=0 && height!=0 && size!=0)break;
		if(video_flag==0)return 0;
	}
	printf("image:%d * %d,%dn",width,height,size);
	unsigned char *rgb_data=malloc(size);
 	/*創(chuàng)建窗口 */
	SDL_Window *window=SDL_CreateWindow("SDL_VIDEO", SDL_WINDOWPOS_CENTERED,SDL_WINDOWPOS_CENTERED,800,480,SDL_WINDOW_ALLOW_HIGHDPI|SDL_WINDOW_RESIZABLE);
    /*創(chuàng)建渲染器*/
	SDL_Renderer *render=SDL_CreateRenderer(window,-1,SDL_RENDERER_ACCELERATED);
	/*清空渲染器*/
	SDL_RenderClear(render);
   /*創(chuàng)建紋理*/
	SDL_Texture*sdltext=SDL_CreateTexture(render,SDL_PIXELFORMAT_IYUV,SDL_TEXTUREACCESS_STREAMING,width,height);
	bool quit=true;
	SDL_Event event;
	SDL_Rect rect;
	while(quit)
	{
		while(SDL_PollEvent(&event))/*事件監(jiān)測(cè)*/
		{
			if(event.type==SDL_QUIT)/*退出事件*/
			{
				quit=false;
				video_flag=0;
				pthread_cancel(pthid);/*殺死指定線程*/
				continue;
			}
		}
		if(!video_flag)
		{
			quit=false;
			continue;
		}
		pthread_mutex_lock(&fastmutex);//互斥鎖上鎖
		pthread_cond_wait(&cond,&fastmutex);
		memcpy(rgb_data,rgb_buff,size);
		pthread_mutex_unlock(&fastmutex);//互斥鎖解鎖
		SDL_UpdateTexture(sdltext,NULL,rgb_data,width);
		//SDL_RenderCopy(render, sdltext, NULL,NULL); // 拷貝紋理到渲染器
		SDL_RenderCopyEx(render, sdltext,NULL,NULL,0,NULL,SDL_FLIP_NONE);
		SDL_RenderPresent(render); // 渲染
	}
	SDL_DestroyTexture(sdltext);/*銷毀紋理*/
    SDL_DestroyRenderer(render);/*銷毀渲染器*/
    SDL_DestroyWindow(window);/*銷毀窗口 */
    SDL_Quit();/*關(guān)閉SDL*/
    pthread_mutex_destroy(&fastmutex);/*銷毀互斥鎖*/
    pthread_cond_destroy(&cond);/*銷毀條件變量*/
	free(rgb_buff);
	free(rgb_data);
	return 0;
}
void *Video_CollectImage(void *arg)
{
	int res=0;
	AVFrame *Input_pFrame=NULL;
	AVFrame *Output_pFrame=NULL;
	printf("pth:%sn",avcodec_configuration());
	/*注冊(cè)設(shè)備*/
	avdevice_register_all();
	/*查找輸入格式*/
	AVInputFormat *ifmt=av_find_input_format("video4linux2");
	if(ifmt==NULL)
	{
		printf("av_find_input_format failedn");
		video_flag=0;
		return 0;
	}
	/*打開(kāi)輸入流并讀取頭部信息*/
	AVFormatContext *ps=NULL;
	res=avformat_open_input(&ps,VIDEO_DEV,ifmt,NULL);
	if(res)
	{
		printf("open input failedn");
		video_flag=0;
		return 0;
	}
	/*查找流信息*/
	res=avformat_find_stream_info(ps,NULL);
	if(res)
	{
		printf("find stream failedn");
		video_flag=0;
		return 0;
	}
	/*打印有關(guān)輸入或輸出格式信息*/
	av_dump_format(ps, 0, "video4linux2", 0);
	/*尋找視頻流*/
	int videostream=-1;
	videostream=av_find_best_stream(ps,AVMEDIA_TYPE_VIDEO,-1,-1,NULL,0);
	printf("videostram=%dn",videostream);
	/*尋找編解碼器*/
	AVCodec *video_avcodec=NULL;/*保存解碼器信息*/
	AVStream *stream = ps->streams[videostream];
	AVCodecContext *context=stream->codec;
	video_avcodec=avcodec_find_decoder(context->codec_id);
	if(video_avcodec==NULL)
	{
		printf("find video decodec failedn");
		video_flag=0;
		return 0;
	}	
	/*初始化音視頻解碼器*/
	res=avcodec_open2(context,video_avcodec,NULL);
	if(res)
	{
		printf("avcodec_open2 failedn");
		video_flag=0;
		return 0;
	}	
	AVPacket *packet=av_malloc(sizeof(AVPacket));/*分配包*/
	AVFrame *frame=av_frame_alloc();/*分配視頻幀*/
	AVFrame *frameyuv=av_frame_alloc();/*申請(qǐng)YUV空間*/
	/*分配空間，進(jìn)行圖像轉(zhuǎn)換*/
	width=context->width;
	height=context->height;
	int fmt=context->pix_fmt;/*流格式*/
	size=av_image_get_buffer_size(AV_PIX_FMT_YUV420P,width,height,16);
	unsigned char *buff=NULL;
	printf("w=%d,h=%d,size=%dn",width,height,size);	
	buff=av_malloc(size);
	rgb_buff=malloc(size);//保存RGB顏色數(shù)據(jù)
	/*存儲(chǔ)一幀圖像數(shù)據(jù)*/
	av_image_fill_arrays(frameyuv->data,frameyuv->linesize,buff,AV_PIX_FMT_YUV420P,width,height, 16);
	/*轉(zhuǎn)換上下文，使用sws_scale（）執(zhí)行縮放/轉(zhuǎn)換操作。*/
	struct SwsContext *swsctx=sws_getContext(width,height, fmt,width,height, AV_PIX_FMT_YUV420P,SWS_BICUBIC,NULL,NULL,NULL);
	/*讀幀*/
	int go=0;
	int Framecount=0;
	printf("read fream buffn");
	while(av_read_frame(ps,packet)>=0 && video_flag)
	{
		Framecount++;
		if(packet->stream_index == AVMEDIA_TYPE_VIDEO)/*判斷是否為視頻*/
		{
			/*解碼一幀視頻數(shù)據(jù)。輸入一個(gè)壓縮編碼的結(jié)構(gòu)體AVPacket，輸出一個(gè)解碼后的結(jié)構(gòu)體AVFrame*/
			res=avcodec_decode_video2(ps->streams[videostream]->codec,frame,&go,packet);
			if(res<0)
			{
				printf("avcodec_decode_video2 failedn");
				break;
			}
			if(go)
			{
				/*轉(zhuǎn)換像素的函數(shù)*/
				sws_scale(swsctx,(const uint8_t * const*)frame->data,frame->linesize,0,height,frameyuv->data,frameyuv->linesize);
				pthread_mutex_lock(&fastmutex);//互斥鎖上鎖
				memcpy(rgb_buff,buff,size);
		        pthread_cond_broadcast(&cond);//廣播喚醒所有線程
		        pthread_mutex_unlock(&fastmutex);//互斥鎖解鎖
			}
		}		
	}
	sws_freeContext(swsctx);/*釋放上下文*/
	av_frame_free(&frameyuv);/*釋放YUV空間*/
	av_packet_unref(packet);/*釋放包*/
	av_frame_free(&frame);/*釋放視頻幀*/
	avformat_close_input(&ps);/*關(guān)閉流*/
	video_flag=0;
	pthread_exit(NULL);	
}

?3.2 Makefile文件

OBJ=get_cameraimage.c
CFLAGS =-I/home/wbyq/src_pack/SDL2-2.0.14/_install/include -I/home/wbyq/src_pack/SDL2-2.0.14/_install/include/SDL2 -L/home/wbyq/src_pack/SDL2-2.0.14/_install/lib
CFLAGS +=-L/home/wbyq/src_pack/SDL2_image-2.0.5/_install/lib -I/home/wbyq/src_pack/SDL2_image-2.0.5/_install/include -I/home/wbyq/src_pack/SDL2_image-2.0.5/_install/include/SDL2
CFLAGS+=-lSDL2 -lpthread -lm -ldl -lSDL2_image -lavcodec -lavfilter -lavutil -lswresample -lavdevice -lavformat -lpostproc -lswscale -lpthread -lstdc++ -lm -lasound
CFLAGS+=-I/home/wbyq/src_pack/ffmpeg-4.2.5/_install/include -L/home/wbyq/src_pack/ffmpeg-4.2.5/_install/lib -I/home/wbyq/src_pack/SDL2-2.0.14/_install/include -I/home/wbyq/src_pack/SDL2-2.0.14/_install/include/SDL2 
app:
	gcc $(OBJ) $(CFLAGS)

?3.3 運(yùn)行效果