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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>
,2+d+Zuh  
#include <fcntl.h>  Fq5u%S  
#include <stdio.h> z;Fz3s7  
#include <sys/ioctl.h> %lGOExV%  
#include <stdlib.h> DS>&|zF5l  
#include <linux/types.h> mH4u@aQ}  
#include <linux/videodev2.h> 2oRwDg&7|  
#include <malloc.h> %<[{zd1C-  
#include <math.h> 9F?-zn;2s  
#include <string.h> ~TeOl|!lE+  
#include <sys/mman.h> 0a#v}w^ *  
#include <errno.h> (E&M[hH+  
#include <assert.h> S]~5iO_bst  
.:B>xg~2  
#define FILE_VIDEO  "/dev/video0" DHx&%]r;D  
#define JPG "./image%d.jpg" P8|ANe1 v  
V2M4g  
typedef struct{ m%>}T 75C^  
    void *start; O8_! !Qd  
    int length; \=mLL|a  
}BUFTYPE; yjH'<  
BUFTYPE *usr_buf; r]D U  
static unsigned int n_buffer = 0; y'I m/{9U  
?!/8~'xA6  
//set video capture ways(mmap) 5>daWmD  
int init_mmap(int fd) ksuePMIK  
{ N-knhA  
    //to request frame cache, contain requested counts _~ei1 G.R  
    struct v4l2_requestbuffers reqbufs; |G$-5 7fk  
    //request V4L2 driver allocation video cache NH}o`x/  
    //this cache is locate in kernel and need mmap mapping \[.qN  
    memset(&reqbufs, 0, sizeof(reqbufs)); %"fO^KA.h]  
    reqbufs.count = 4; RWo7_XO  
    reqbufs.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; 6NhGTLI  
    reqbufs.memory = V4L2_MEMORY_MMAP; !G0Mg; ,  
aX6}:"R2C  
    if(-1 == ioctl(fd,VIDIOC_REQBUFS,&reqbufs)){ K[0z$T\  
        perror("Fail to ioctl 'VIDIOC_REQBUFS'"); ?wCX:? g  
        exit(EXIT_FAILURE); #\n* Qg4p  
    } D1v0`od'  
J5HK1  
    n_buffer = reqbufs.count; [u2t1^#Ol  
    printf("n_buffer = %d\n", n_buffer); 9#&H'mG  
    usr_buf = calloc(reqbufs.count, sizeof(BUFTYPE)); QRBx}!:NZ#  
    if(usr_buf == NULL){ X;GU#8W  
        printf("Out of memory\n"); 2;s[m3  
        exit(-1); OY:rcGc`t  
    } a`#lYM%(>  
-WF((s;<#  
    //map kernel cache to user process ]4 c+{  
    for(n_buffer = 0; n_buffer < reqbufs.count; ++n_buffer){ -.8K"j{N  
        //stand for a frame 0H^*VUyW/  
        struct v4l2_buffer buf; `67i1w`  
        memset(&buf, 0, sizeof(buf)); Q~svtN  
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; .Wy'  
        buf.memory = V4L2_MEMORY_MMAP; 'ROz|iJ  
        buf.index = n_buffer; GN! R<9  
         E?P>s T3B  
        //check the information of the kernel cache requested >(.|oT\Tb  
        if(-1 == ioctl(fd,VIDIOC_QUERYBUF,&buf)) <f8j^  
        { .udLMS/_  
            perror("Fail to ioctl : VIDIOC_QUERYBUF"); ,(K-;Id4  
            exit(EXIT_FAILURE); <,n:w[+!`P  
        } R2-F@_  
y2s(]# 8  
#Pf<2S  
    printf(" buf.length =%d\n", buf.length); @P75f5p}<  
42"nbJ  
Q>Z~={"  
        usr_buf[n_buffer].length = buf.length; ]YFjz/f  
        usr_buf[n_buffer].start = S\A0gOL^  
            mmap( 2sk7E'2(  
                    NULL, Fb%?qaLmCv  
                    buf.length, d<Q%h?E  
                    PROT_READ | PROT_WRITE, _LC*_LT_  
                    MAP_SHARED, Hv,ll1@h  
                    fd, 4=|Q2qgFV  
                    buf.m.offset A-=hvJ5T  
                ); //mmap(0, fbSize, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); UWV%  y P  
>uq0}HB$a  
 'F.P93  
     if(MAP_FAILED == usr_buf[n_buffer].start) Qr3!6  
        { EwFq1~  
            perror("Fail to mmap"); q@[F|EF=  
            exit(EXIT_FAILURE); eUB!sR%  
        } (Q% @]  
h`N2M,  
    printf(" usr_buf[%d].start=0x%x length=0x%x \n" , n_buffer, usr_buf[n_buffer].start ,buf.length); *p\Zc*N;%  
YF-E1`+?<  
Er~KX3vF  
         H8 ? Y{H  
    } uZrp ^  
    return 0; %~Rg`+  
} kG!hqj  
d!R+-Fp  
//initial camera device sV{\IgH/x  
int init_camera_device(int fd) (P-^ PNz&  
{ i^.eX VV/  
    //decive fuction, such as video input $u~ui@kB  
    struct v4l2_capability cap; a<r,LE  
    //video standard,such as PAL,NTSC X5J)1rL  
    struct v4l2_standard std; DAWF =p]  
    //frame format "%^_.Db>|  
    struct v4l2_format tv_fmt; ly*v|(S&  
    //check control )/)u.$pi  
    struct v4l2_queryctrl query; ]9/A=p?J@  
    //detail control value L{F]uz_[x  
    struct v4l2_fmtdesc fmt; j0{`7n  
    int ret; N'EZJ oH  
    //get the format of video supply +O 7( >a  
    memset(&fmt, 0, sizeof(fmt)); SIrNZ^I  
    fmt.index = 0; fTy:Re  
    //supply to image capture Icg-rwa<Z  
    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; `+\$  
    // show all format of supply c8uw_6#r(D  
    printf("Support format:\n"); E#rQJ  
    while(ioctl(fd, VIDIOC_ENUM_FMT, &fmt) == 0){ #n|5ng|CJ  
        fmt.index++; }O@>:?U  
        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); ANw1P{9*  
    } ^"?a)KC  
    //check video decive driver capability ~s HdOMw  
    ret = ioctl(fd, VIDIOC_QUERYCAP, &cap); @hg[v`~  
    if(ret < 0){ L QV@]z&  
        perror("Fail to ioctl VIDEO_QUERYCAP"); MjC<N[WO>N  
        exit(EXIT_FAILURE); zu @|"f^`  
    } K a(B&.  
ZXYyG`3+  
    //judge wherher or not to be a video-get device CS~onf<xz  
    if(!(cap.capabilities & V4L2_BUF_TYPE_VIDEO_CAPTURE)) ^lV}![do!  
    { # 2^H{7  
        printf("The Current device is not a video capture device\n"); dR\yRC]I  
        exit(-1); JX 5/PCO  
    } 3R%JmLM+R9  
\HzmhQb+m  
    //judge whether or not to supply the form of video stream o;Z"I&  
    if(!(cap.capabilities & V4L2_CAP_STREAMING)) 7:vl -ZW  
    { .cs x"JC  
        printf("The Current device does not support streaming i/o\n"); "]]LQb$  
        exit(EXIT_FAILURE); p )JR5z  
    } #btf|\D  
p!:oT1U  
    //set the form of camera capture data !|4]V}JQ  
S5>ztK.e  
PsNrCe%e  
7"'PfP4c  
    tv_fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; >Df; 1:U  
(VM CVZ  
7 SJ=2  
#if 0 q9ra  
    tv_fmt.fmt.pix.width = 640; }1 qQ7}v  
    tv_fmt.fmt.pix.height = 360; dX1jn;7  
#else T=-UcF  
o#wly%i')  
    tv_fmt.fmt.pix.width = 1280; Ir>4-@  
    tv_fmt.fmt.pix.height = 960; 7=?!B#hm !  
p#P<V%  
^ fC2o%3^  
#endif )m =xf1  
^\B4]'+^j  
AeEdqX)  
     (,o@/ -o  
    tv_fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG; JGvhw,g  
    //V4L2_PIX_FMT_YUYV d]sqj\Q57  
    tv_fmt.fmt.pix.field = V4L2_FIELD_INTERLACED; .gC.T`/m  
    if (ioctl(fd, VIDIOC_S_FMT, &tv_fmt)< 0) { 9Xg7=(#  
        printf("VIDIOC_S_FMT\n"); GP4!t~"1  
        exit(-1); k6(</uRj  
        close(fd); dYD;Z<l  
    } uQ_C<ii"W  
    //initial video capture way(mmap) %b*N.v1+  
    init_mmap(fd); jcj8w  
    return 0; n!Y_SPg   
} <\$"U5"`  
Wm-$l  
int open_camera_device() -DHzBq=H  
{ fTR6]i;  
    int fd; aG;F=e  
    //open video device with block pEcYfj3M  
    fd = open(FILE_VIDEO, O_RDWR /* required */ | O_NONBLOCK, 0);//打开设备 *8,W$pe3  
    if(fd < 0){ P]^OSPRg  
        perror(FILE_VIDEO); l9|K,YVW  
        exit(EXIT_FAILURE); {~9HJDcM  
    } |0}Xb|+  
    return fd; Ot47.z  
} r@r*|50  
!$1qnsz  
int start_capture(int fd) AC <2.i_  
{ QpQ2hNf  
    unsigned int i; ZJWpb  
    enum v4l2_buf_type type;  .GJbrz  
    //place the kernel cache to a queue o>(<:^x9  
    for(i = 0; i < n_buffer; i++){ 1o\2\B=k{  
        struct v4l2_buffer buf; fh)eL<I  
        memset(&buf, 0, sizeof(buf)); :35h0;8+  
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; <?IDCOt ?  
        buf.memory = V4L2_MEMORY_MMAP; iP9]b&  
        buf.index = i; BQWg L  
&D[M<7T  
        if(-1 == ioctl(fd, VIDIOC_QBUF, &buf)){ }a!|n4|`  
            perror("Fail to ioctl 'VIDIOC_QBUF'"); ,sc#l<v  
            exit(EXIT_FAILURE); 53aJnxX  
        } Mx, 5  
    } C TG^lms  
Ww8U{f  
    //start capture data U1/I( w  
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE; 6P >Y2xV:  
    if(-1 == ioctl(fd, VIDIOC_STREAMON, &type)){ W^^0Rh_  
        printf("i=%d.\n", i); S[9b I&C  
        perror("VIDIOC_STREAMON"); v7@"9Uw}  
        close(fd); ^kcuRJ0*$  
        exit(EXIT_FAILURE); eSObOG/  
    } 7Z:HwZ  
    return 0; FLQke"6i0:  
} v `/nX->  
X:`=\D  
vgtAJp+p*  
int process_image(void *addr, int length) i03S9J  
{ um$U3'0e  
    int fd; dkEbP*y Xg  
    static int num = 0; L''VBY"?  
    char image_name[20]; 8g{Mv#b%  
cu5}(  
    printf("%s addr = 0x%x  length= %d \n" , __func__,addr,length); ']2d^'TH  
*^]  
    sprintf(image_name, JPG, num++); P]}:E+E<.I  
9:RV5Dt  
    if((fd= open(image_name,O_CREAT|O_WRONLY)) == NULL){ "'``O~08/  
\2El>>  
         GNmP_N  
        printf("Fail to fopen"); 6@# =z  
        exit(EXIT_FAILURE); 4IW90"uc  
         R6 ej  
    } ts[8;<YD  
     tOnOzD  
    write(fd,addr, length); * wqR.n?  
    sync( ); Yy/,I]F  
    close(fd); _+)OL-  
     d=+zOF  
       return 0;  7Tr '<(A  
   C<:wSS^@1  
   @~$=96^  
  } 0[ "CP:u  
>(n /  
z<A8S=s6n  
W=S^t_F  
GfP'  
|uFb(kL[U  
?T%"Jgy8  
(]mBAQ#hw  
SLkgIb~'X  
{be|G^.c  
b?Q$UMAbH  
 wDiq~!  
A9Ea}v9:  
int read_frame(int fd) G~&q  
{ V0,5c`H c  
    struct v4l2_buffer buf; E<B/5g!  
    unsigned int i; ,{iMF (Nj  
    memset(&buf, 0, sizeof(buf)); $@{ d\@U  
B[w.8e5  
   printf("%s run   place 1 \n",__func__); UZiL NKc  
~9!@BL\  
     It3@ Cd>  
    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; vqUYr  
    buf.memory = V4L2_MEMORY_MMAP; OS L~a_  
    //put cache from queue VWXyN  
    if(-1 == ioctl(fd, VIDIOC_DQBUF,&buf)){ j}@LiH'Q  
        perror("Fail to ioctl 'VIDIOC_DQBUF'"); 33}p02#  
        exit(EXIT_FAILURE); ^N ;TCn  
    } 'R$/Qt;uA  
V.Lk70 \  
    assert(buf.index < n_buffer); o4rf[.z  
    //read process space's data to a file `7`` 1TL  
    printf("buf.index=%d\n",buf.index); l'!_km0{d  
bS|h~B]rd  
    process_image(usr_buf[buf.index].start, buf.bytesused); 's"aPqF?  
E'+z.~+  
4|j Pr J  
    printf("%s run   place 2 \n",__func__); Ttb?x<)+8  
'|tmmoY6a:  
    if(-1 == ioctl(fd, VIDIOC_QBUF,&buf)){ i-95>ff  
        perror("Fail to ioctl 'VIDIOC_QBUF'"); 6]!Jo)BF  
        exit(EXIT_FAILURE); y(C',Xn  
    } 8-L -W[  
(S=CxK  
b83m'`vRM  
    printf("%s run   place 3 \n",__func__); >"zN`  
     {c $8?6  
    return 1; s/;S2l$`  
} Yv{$XI7  
'OhGSs|  
int mainloop(int fd) >^@~}]L  
{ !a%_A^t7  
    int count =20; 7/=r-  
UY\E uA9  
    while(count-- > 0) @9]TjZd  
    { 4Dd]:2|D  
        for(;;) }&l%>P  
        { /I`-  
            fd_set fds; e/)Vx'd`+  
            struct timeval tv; `- 9p)@'8k  
            int r; >T14 J'\  
H7{kl  
            printf("count = %d \n", count); o8A(Cg}  
         "GxQ9=Z  
            FD_ZERO(&fds);  </Dv?  
            FD_SET(fd,&fds); )4GCL(&  
w/ID y Q  
            /*Timeout*/ *u>[  
            tv.tv_sec = 200; _^0UK|[  
            tv.tv_usec = 0; 0e'@Xo2e  
            r = select(fd + 1,&fds,NULL,NULL,&tv); UQT=URS  
I<&) P#"  
            if(-1 == r) Z7MGBwP(  
            { `4|:8@,3{  
                if(EINTR == errno) :{#w-oC>6P  
                    continue; 3qp\jh=FE  
                perror("Fail to select"); `y&2Bf  
                exit(EXIT_FAILURE); EBUCG"e  
            } )c0Dofhg  
&X}i%etp^2  
            if(0 == r) al]-*=v7}  
            { 9iK%@k  
                fprintf(stderr,"select Timeout\n"); V9D>Xh!0H  
                exit(-1); Pfg.'Bl  
            } {9./-  
|198A,^  
            if(read_frame(fd)) b5%T)hn=  
                break; _/}/1/y$Y  
        } R6irL!akAd  
    } @w;&:J9m  
    return 0; 3gs7Xj%N  
} mx0EEU*  
c38ENf  
void stop_capture(int fd) \2 `|eo  
{ lM%3 ?~?Q&  
    enum v4l2_buf_type type; ekSSqj9";  
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE; H')8p;~{}  
    if(-1 == ioctl(fd,VIDIOC_STREAMOFF,&type)) =i Wn T  
    { N MH'4R  
        perror("Fail to ioctl 'VIDIOC_STREAMOFF'"); &>Nw>V  
        exit(EXIT_FAILURE); V.kf@  
    } yT C+5_7  
    return; mA\}zLw+r9  
} {60U6n  
f;a55%3c  
void close_camera_device(int fd) c"S{5xh0&  
{ iq`caoi  
    unsigned int i; ys} I~MK-  
    for(i = 0;i < n_buffer; i++) z7]GZF  
    { ~|8-Mo1ce  
        if(-1 == munmap(usr_buf.start,usr_buf.length)){ `z6I][Uf  
            exit(-1); 39Tlt~Psz  
        } OP\m~1  
    } qbD[<T  
    free(usr_buf); =a_ >")  
2j-^F  
    if(-1 == close(fd)) pn aSOyR  
    { F+m;y  
        perror("Fail to close fd"); d`J~w/] `\  
        exit(EXIT_FAILURE); sk~inIj-  
    } ee .,D  
    return; N|  
} a/lTQj]A  
t'bhA20Z\  
int main() *f3? 0w  
{ mBg$eiGTB  
OCbwV7q:  
G Y+li {  
    int fd; (cm8x  
    fd = open_camera_device(); h~u|v[@{J  
    init_camera_device(fd); 4)E$. F^   
    start_capture(fd); k[5:]5lp+  
    mainloop(fd); o%[swoM@  
    stop_capture(fd); Apc!!*7  
    close_camera_device(fd); `E8D5'tt  
D` 2w>{Y  
   RZqou|ki  
    return 0; b_a6|  
} 4* V[^mht  
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离线thanky0u58

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谢谢分享。楼主做出实物了吗
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