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发一份能过 V4L2 接口 读到摄像头图片信息 并将其保存下来的源码 [复制链接]

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<私密信息仅自己能看>
$#JVI:  
#include <fcntl.h> PyxN_agf  
#include <stdio.h> d#:J\2V"R  
#include <sys/ioctl.h> p}|wO&4h  
#include <stdlib.h> wvaIgy%z  
#include <linux/types.h> 9.#R?YP$  
#include <linux/videodev2.h> ]JPPL4wAT  
#include <malloc.h> x  Bw.M{  
#include <math.h> &`Z)5Ww  
#include <string.h> d*(Bs $De  
#include <sys/mman.h> bK;a V&  
#include <errno.h> -t'oW*kdL  
#include <assert.h> ?F!J@Xn5  
u,SZ-2K!7~  
#define FILE_VIDEO  "/dev/video0" /~huTKA}  
#define JPG "./image%d.jpg" ]%8;c  
RW[<e   
typedef struct{ n >PM_W  
    void *start; Wc;D{p?Lb  
    int length; tUF]f6  
}BUFTYPE; "(&`muIc  
BUFTYPE *usr_buf; X&oy.Roo  
static unsigned int n_buffer = 0; N_[ Q.HD"  
VD`2lGdF  
//set video capture ways(mmap) @5VZ   
int init_mmap(int fd) QGG(I7{-  
{ j =%-b]  
    //to request frame cache, contain requested counts 7t Kft  
    struct v4l2_requestbuffers reqbufs; \1'R}B@;  
    //request V4L2 driver allocation video cache HwMsP$`q  
    //this cache is locate in kernel and need mmap mapping J$*["y`+  
    memset(&reqbufs, 0, sizeof(reqbufs)); N%E2BJ?  
    reqbufs.count = 4; PH!B /D5G  
    reqbufs.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; GJfNO-  
    reqbufs.memory = V4L2_MEMORY_MMAP;  pytfsVM  
WREGRy  
    if(-1 == ioctl(fd,VIDIOC_REQBUFS,&reqbufs)){ i1@gHk  
        perror("Fail to ioctl 'VIDIOC_REQBUFS'"); zGz'2, o3  
        exit(EXIT_FAILURE); ]!o,S{a&  
    } 9],"AjD  
\J&#C(pn  
    n_buffer = reqbufs.count; 0 3 $ W  
    printf("n_buffer = %d\n", n_buffer); 1Klu]J%  
    usr_buf = calloc(reqbufs.count, sizeof(BUFTYPE)); TiEJyd`P  
    if(usr_buf == NULL){ [z@RgDX v  
        printf("Out of memory\n"); h,?Yw+#o"  
        exit(-1); n8aiGnd=v  
    } P,=J"%a-  
zb,`K*Z{  
    //map kernel cache to user process ([o:_5/8I  
    for(n_buffer = 0; n_buffer < reqbufs.count; ++n_buffer){ x+`3G.  
        //stand for a frame 1RHH<c%2n  
        struct v4l2_buffer buf; "fd=(& M*l  
        memset(&buf, 0, sizeof(buf)); irj}:f;!eF  
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; sswAI|6ou  
        buf.memory = V4L2_MEMORY_MMAP; 2;r^~:  
        buf.index = n_buffer; iGNKf|8{  
         *.Hnt\4|  
        //check the information of the kernel cache requested 5z]KkPQ  
        if(-1 == ioctl(fd,VIDIOC_QUERYBUF,&buf)) 5j5t?G;d,  
        { 4>`w9   
            perror("Fail to ioctl : VIDIOC_QUERYBUF"); ]r5Xp#q2  
            exit(EXIT_FAILURE); dh`A(B{hfc  
        } UpBYL?+L  
_Fy:3,(  
aKr4E3`  
    printf(" buf.length =%d\n", buf.length); ~36XJ  
Ggjb86v\  
*9^k^h(r&4  
        usr_buf[n_buffer].length = buf.length; scwlW b<N  
        usr_buf[n_buffer].start = ?IO/zkeXg  
            mmap( Yr0i9Qow  
                    NULL, 8#-}3~l[  
                    buf.length, :$d3a"]  
                    PROT_READ | PROT_WRITE, iAhRlQ{Qu  
                    MAP_SHARED, RlI qH;n  
                    fd, 8Wp1L0$B  
                    buf.m.offset )+R3C%  
                ); //mmap(0, fbSize, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 7@]hu^)rry  
#]^`BQ>  
f 2f $aZ  
     if(MAP_FAILED == usr_buf[n_buffer].start) J3^Ir [  
        { ]2 N';(R  
            perror("Fail to mmap"); PmTd+Gj$  
            exit(EXIT_FAILURE); 2b1:Tt9  
        } ||NCVGJG  
n&&y\?n  
    printf(" usr_buf[%d].start=0x%x length=0x%x \n" , n_buffer, usr_buf[n_buffer].start ,buf.length); :7*\|2zA  
EJY:C9W  
|REU7?B  
         -ZJ:<  
    } JDlIf  
    return 0; K?WqAVK  
} i?9Lf  
Zwl?*t\D  
//initial camera device X / "H+l  
int init_camera_device(int fd) ] UTP~2N  
{ a)b@en;v  
    //decive fuction, such as video input VQ`O;n6/`  
    struct v4l2_capability cap; f}3bYF  
    //video standard,such as PAL,NTSC =z.AQe+   
    struct v4l2_standard std; [r'M_foga*  
    //frame format EQ-~e   
    struct v4l2_format tv_fmt; VNPd L  
    //check control IC~D?c0H:  
    struct v4l2_queryctrl query; GV/FK{v5  
    //detail control value H& +s&F{%  
    struct v4l2_fmtdesc fmt; n_hD  
    int ret; h~t]WN  
    //get the format of video supply bN)?szh&Y  
    memset(&fmt, 0, sizeof(fmt)); c8MNo'h  
    fmt.index = 0; dno*Usx5d0  
    //supply to image capture ['<rfK  
    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; "zc!QHpSd  
    // show all format of supply c:5BQr '  
    printf("Support format:\n"); Joj8'  
    while(ioctl(fd, VIDIOC_ENUM_FMT, &fmt) == 0){ /8R1$7  
        fmt.index++; O;"%z*g.  
        printf("pixelformat = ''%c%c%c%c''\ndescription = ''%s''\n",fmt.pixelformat & 0xFF, (fmt.pixelformat >> 8) & 0xFF,(fmt.pixelformat >> 16) & 0xFF, (fmt.pixelformat >> 24) & 0xFF,fmt.description); FT6cOMu  
    } 9X~^w_cdk  
    //check video decive driver capability ~ME=!;<_  
    ret = ioctl(fd, VIDIOC_QUERYCAP, &cap); llJ)u!=5  
    if(ret < 0){ g!UM8I-$  
        perror("Fail to ioctl VIDEO_QUERYCAP"); >6j`ZWab>  
        exit(EXIT_FAILURE); n\4+xZr  
    } Qfi5fp=f  
5`Z#m:+u  
    //judge wherher or not to be a video-get device DJ.Ct4  
    if(!(cap.capabilities & V4L2_BUF_TYPE_VIDEO_CAPTURE)) HIAd"}^  
    { To+{9"$,  
        printf("The Current device is not a video capture device\n"); ;RI,zQ  
        exit(-1); va.wdk g  
    } <rI~+J]s  
]]4E)j8  
    //judge whether or not to supply the form of video stream V{r@D!}  
    if(!(cap.capabilities & V4L2_CAP_STREAMING)) wv$=0zF  
    { z?^p(UH  
        printf("The Current device does not support streaming i/o\n"); @lI/g  
        exit(EXIT_FAILURE); n:+M Nr  
    } WUWQcJj  
ADDpm-]  
    //set the form of camera capture data '*:YC  
I{ $|Ed1  
,MJZ*"V/3  
vL7}0n>tz  
    tv_fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; 5P4 >xv[  
&nYmVwi?"Q  
LO229`ARr|  
#if 0 |V& k1{V  
    tv_fmt.fmt.pix.width = 640; +?p ;,Z%5  
    tv_fmt.fmt.pix.height = 360; 5`J. ic  
#else ]_h"2|  
li[g =A,  
    tv_fmt.fmt.pix.width = 1280; d=pq+  
    tv_fmt.fmt.pix.height = 960; lF<(yF5  
j:#[voo7  
]pt @  
#endif $f%_ 4 =  
J=sQ].EK  
G2rvi=8=  
     K;K tx>Z/  
    tv_fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG; r |(Lb'k  
    //V4L2_PIX_FMT_YUYV l"Css~^  
    tv_fmt.fmt.pix.field = V4L2_FIELD_INTERLACED; 4PdFq*A  
    if (ioctl(fd, VIDIOC_S_FMT, &tv_fmt)< 0) { *KM CU m  
        printf("VIDIOC_S_FMT\n"); f%af.cR*  
        exit(-1); XjC+kH  
        close(fd); D 6(w}W  
    } 2Y,s58F  
    //initial video capture way(mmap) `CV a`%  
    init_mmap(fd); Y#G '[N>  
    return 0; SWu=n1J.?H  
} 1\BECP+  
sXFD]cF  
int open_camera_device() 6Z3v]X  
{ s=q}XIWK  
    int fd; QeK~A@|F&  
    //open video device with block sU>*S$X8  
    fd = open(FILE_VIDEO, O_RDWR /* required */ | O_NONBLOCK, 0);//打开设备 Eb*DP_  
    if(fd < 0){ 0-@waK  
        perror(FILE_VIDEO); %n( s;/_  
        exit(EXIT_FAILURE); sx9 N8T3n  
    } A;kB"Tx  
    return fd; kAqk~.  
} xKxWtZ0  
I++!F,pB  
int start_capture(int fd) d;>:<{z@CD  
{ /];F4AO5  
    unsigned int i; -n6C~Yx  
    enum v4l2_buf_type type; i"-j:b:c<  
    //place the kernel cache to a queue d{0>R{uac  
    for(i = 0; i < n_buffer; i++){ 4m~\S)ad  
        struct v4l2_buffer buf; GovGh? X#x  
        memset(&buf, 0, sizeof(buf)); 'h:4 Fzo<  
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; 5~qr+la  
        buf.memory = V4L2_MEMORY_MMAP; re<"%D  
        buf.index = i; 9J<KR #M  
X%;,r 2g  
        if(-1 == ioctl(fd, VIDIOC_QBUF, &buf)){ sg3%n0Ms.W  
            perror("Fail to ioctl 'VIDIOC_QBUF'"); NoMEe<  
            exit(EXIT_FAILURE); @wpm;]  
        } ( \]_/ W  
    } M+Dkn3bx  
<)M?qkjb  
    //start capture data LnBkd:>}  
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE; Tux~4W  
    if(-1 == ioctl(fd, VIDIOC_STREAMON, &type)){ R (6Jvub"I  
        printf("i=%d.\n", i); TiH(HW|:  
        perror("VIDIOC_STREAMON"); I qma vnM#  
        close(fd); e Q0bx&  
        exit(EXIT_FAILURE); /6>2,S8Ar  
    } -QRKDp  
    return 0; rt"\\sOlMB  
} B64%| S  
Y#uf 2>J  
;]p#PNQ0  
int process_image(void *addr, int length) m0 `wmM  
{ :qI myaGQ  
    int fd; D@mDhhK_  
    static int num = 0; Nz2}Ma 2  
    char image_name[20]; L-Z1Xs  
\&SP7~-eq  
    printf("%s addr = 0x%x  length= %d \n" , __func__,addr,length); :kgwKuhL  
 Wkf)4!  
    sprintf(image_name, JPG, num++); a-hF/~84S:  
!]W6i]p  
    if((fd= open(image_name,O_CREAT|O_WRONLY)) == NULL){ J)*y1   
3wD6,x-e   
         x *(pr5k  
        printf("Fail to fopen"); +W-sb5)  
        exit(EXIT_FAILURE); F> ..eK  
         Ff|?<\x0}A  
    } eGZId v1  
     S0\:1B  
    write(fd,addr, length); Q5baY\"9^  
    sync( ); bE0cW'6r  
    close(fd); ~bg FU  
     t:W`=^  
       return 0; x_#yH3kJ  
   T"3WB o  
   ?eeE[F  
  } -Ndd6O[ a5  
KWM.b"WnXr  
1#XMUbFc  
\\BblzGMR  
24]O0K  
Z#d_<e?  
'j>Q7M7q{  
.{~ygHQ`f  
CI ~+(+q  
 _8t{4C  
?f:FmgQk  
XVE(p3-  
4_)@Nq  
int read_frame(int fd) ;p) gTQa  
{ mR?OSeeB  
    struct v4l2_buffer buf; v;irk<5  
    unsigned int i; ig3uY#  
    memset(&buf, 0, sizeof(buf)); zPZy#7/A  
=p ^Sn,t  
   printf("%s run   place 1 \n",__func__); 4WU 6CN  
Z-Zox-I1}-  
     >|mmJ4T  
    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; WY  #pzBA  
    buf.memory = V4L2_MEMORY_MMAP; -&%#R_RV  
    //put cache from queue eCdMDSFO3  
    if(-1 == ioctl(fd, VIDIOC_DQBUF,&buf)){ vxY7/_]  
        perror("Fail to ioctl 'VIDIOC_DQBUF'"); "m(HQ5e)*  
        exit(EXIT_FAILURE); nTp?  
    } ]#KZ W)M  
NgQ {'H[Y  
    assert(buf.index < n_buffer); OlQ7Yi>  
    //read process space's data to a file n*hHqZl  
    printf("buf.index=%d\n",buf.index); xLX:>64'o>  
<LH(>  
    process_image(usr_buf[buf.index].start, buf.bytesused);  E*i <P  
89?AcZ.D  
^0c:ro  
    printf("%s run   place 2 \n",__func__); J_<ENs-  
FNtcI7  
    if(-1 == ioctl(fd, VIDIOC_QBUF,&buf)){ !Zlvz%X  
        perror("Fail to ioctl 'VIDIOC_QBUF'"); =X]$J@j  
        exit(EXIT_FAILURE); <Hig,(=`.  
    } j)]mN$Sa:  
0Evq</  
[C.Pzo  
    printf("%s run   place 3 \n",__func__); eBlVb*nmq  
     BbnY9"  
    return 1; X70G@-w  
} d>VerZZU  
u#ag|b/C:  
int mainloop(int fd) rs`H':a/  
{ *&^`Uk,[  
    int count =20; uR"(0_  
-[^aWNqyJ  
    while(count-- > 0) now\-XrS  
    { #EgFB}>1  
        for(;;) ? L|m:A`  
        { $&OoxC  
            fd_set fds; 8%@7G*  
            struct timeval tv; &>XIK8*  
            int r; [yJcM [p\  
[f!sBJ!  
            printf("count = %d \n", count); t n>$5}^;  
         =TE6R 0b  
            FD_ZERO(&fds); h}nceH0s3d  
            FD_SET(fd,&fds); aq@/sMn  
4en[!*  
            /*Timeout*/ QI0d:7!W1  
            tv.tv_sec = 200; Lp`q[Z*  
            tv.tv_usec = 0; f,wB.MN  
            r = select(fd + 1,&fds,NULL,NULL,&tv); /\q1,}M  
tg_v\n  
            if(-1 == r) 2WE_NEpJI  
            { _e E(P1  
                if(EINTR == errno) pdUrVmW"'  
                    continue; 1O"7%Pvw  
                perror("Fail to select"); 7j8nDX<  
                exit(EXIT_FAILURE); 8vjaQ5  
            } tF}Vs}  
!yI , ~`Z  
            if(0 == r) Ei2hI  
            { &-mPj82R  
                fprintf(stderr,"select Timeout\n"); FJ#:RC  
                exit(-1); ~G+o;N,V  
            } 'Y Bz?l9  
38ChS.(  
            if(read_frame(fd)) qq9fZZb  
                break; |j3mI\ANF  
        } uQIa"u7  
    } A%qlB[!:  
    return 0; EZlcpCS  
} ?nZQTO7  
@Fv"j9j-3G  
void stop_capture(int fd) //9Ro"  
{ !#wd~: H  
    enum v4l2_buf_type type; w 4-E@>%  
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE; ]k &Y )  
    if(-1 == ioctl(fd,VIDIOC_STREAMOFF,&type)) 8FYcUvxfT  
    { >|1.Z'r/  
        perror("Fail to ioctl 'VIDIOC_STREAMOFF'"); )FVW/{NF@q  
        exit(EXIT_FAILURE); wcDHx#~  
    } nG hFYQl  
    return; <!gq9  
} +o^b ,!  
x;w&JS1 V  
void close_camera_device(int fd) fbgq+f`\  
{ a7KP_[_(  
    unsigned int i; A14}  
    for(i = 0;i < n_buffer; i++) cK6M8:KW  
    { RR R'azT  
        if(-1 == munmap(usr_buf.start,usr_buf.length)){ 8#b>4 Dx  
            exit(-1); $Pv;>fHu  
        } =iF}41a  
    } o_C j o  
    free(usr_buf); `3GC}u>}  
7v\K,P8  
    if(-1 == close(fd)) =23JE'^=  
    { U,q ]  
        perror("Fail to close fd"); S,A\%:Va  
        exit(EXIT_FAILURE); OJ0Dw*K<  
    } 94Wf ]  
    return; k=L(C^VP  
} ?fF{M%i-%  
G4DuqN~2m  
int main() ^,F8 ha  
{ N]qX^RSb  
(9R;a np  
Pt<lHfd  
    int fd; 2' fg  
    fd = open_camera_device(); Q(Uj5aX  
    init_camera_device(fd); O :P%gz4  
    start_capture(fd); E5@U~|V[  
    mainloop(fd); PW a!7n#A  
    stop_capture(fd); 'U=D6X%V9m  
    close_camera_device(fd); O{WJi;l  
'Y`.0T[&  
   7I.7%m,g  
    return 0; 5<1,`Bq@  
} ;533;(d* o  


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