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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>
} p `A>  
#include <fcntl.h> f&!{o=  
#include <stdio.h> LwcAF g|  
#include <sys/ioctl.h> xE- _Fv9  
#include <stdlib.h> SW7AG;c=  
#include <linux/types.h> ` >[Offhd  
#include <linux/videodev2.h> v.F|8 cG  
#include <malloc.h> %xdyG Al:  
#include <math.h> 3&zcdwPj  
#include <string.h> up2wkc8  
#include <sys/mman.h> vngn^2  
#include <errno.h> Dlg9PyQ  
#include <assert.h> R%6KxN)+@  
S3^(L   
#define FILE_VIDEO  "/dev/video0" AbIYdFXB  
#define JPG "./image%d.jpg"  ?%*p!m  
>,x``-  
typedef struct{ [I,s:mn  
    void *start; 4VhKV JX  
    int length; VjJ}q*/3e  
}BUFTYPE; ?u>A2Vc!  
BUFTYPE *usr_buf; 4wPP/`  
static unsigned int n_buffer = 0; cToT_Mk  
a1z*Z/!5  
//set video capture ways(mmap) _Uhl4Mh  
int init_mmap(int fd) ,8o Y(h  
{ 0+NGFX \p  
    //to request frame cache, contain requested counts ;)z+dd#3  
    struct v4l2_requestbuffers reqbufs; /%TL{k&m$  
    //request V4L2 driver allocation video cache Z  GrDa  
    //this cache is locate in kernel and need mmap mapping  tk+4noA  
    memset(&reqbufs, 0, sizeof(reqbufs)); P>'29$1'  
    reqbufs.count = 4; gnlU  
    reqbufs.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; =l>=]O~h  
    reqbufs.memory = V4L2_MEMORY_MMAP; n@J>,K_B  
,,;vG6^a  
    if(-1 == ioctl(fd,VIDIOC_REQBUFS,&reqbufs)){ ZUS06# t}  
        perror("Fail to ioctl 'VIDIOC_REQBUFS'"); \pXo~;E\  
        exit(EXIT_FAILURE); NtkZ\3  
    } ^M+aQg%  
:(;ho.zz  
    n_buffer = reqbufs.count; t c{Qd&"(  
    printf("n_buffer = %d\n", n_buffer); A}i>ys  
    usr_buf = calloc(reqbufs.count, sizeof(BUFTYPE)); =oTj3+7  
    if(usr_buf == NULL){ #lF 2q w  
        printf("Out of memory\n"); 6 2t 9SY  
        exit(-1); w!OYH1ds]_  
    } e8{!Kjiz  
vJ e c+a  
    //map kernel cache to user process 4c<\_\\ck  
    for(n_buffer = 0; n_buffer < reqbufs.count; ++n_buffer){ fzUG1|$e  
        //stand for a frame 7h`t-6<!q  
        struct v4l2_buffer buf; @>`qfy?  
        memset(&buf, 0, sizeof(buf)); p ^Y2A  
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; <tdsUh:?&  
        buf.memory = V4L2_MEMORY_MMAP; u24XuSe$  
        buf.index = n_buffer; >]kZ2gVt  
         w@H@[x  
        //check the information of the kernel cache requested 3|D.r-Q  
        if(-1 == ioctl(fd,VIDIOC_QUERYBUF,&buf)) M|7][! <G!  
        { 1^2]~R9,9  
            perror("Fail to ioctl : VIDIOC_QUERYBUF"); `t+;[G>ZE  
            exit(EXIT_FAILURE); VP*B<u  
        } I>lblI$7  
!\\OMAf7  
A @e!~  
    printf(" buf.length =%d\n", buf.length); yUs/lI, Q  
cCcJOhk|d  
H=9{|%iS  
        usr_buf[n_buffer].length = buf.length; bjq.nn<=  
        usr_buf[n_buffer].start = dRUmC H  
            mmap( B.~[m}  
                    NULL, 0Z{u;FI  
                    buf.length, 6\? 2=dNX  
                    PROT_READ | PROT_WRITE, \W|ymV_Ki  
                    MAP_SHARED, eF?jNO3  
                    fd, t-SZBNb  
                    buf.m.offset %!R\-Vej  
                ); //mmap(0, fbSize, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); u$qazj  
v)nBp\fjxp  
.g_^! t  
     if(MAP_FAILED == usr_buf[n_buffer].start) _p<wATv?7t  
        { )"%J~:`h}  
            perror("Fail to mmap"); gp+@+i>b+[  
            exit(EXIT_FAILURE); RtEx WTc  
        } 2#Qw  
QiaBZAol  
    printf(" usr_buf[%d].start=0x%x length=0x%x \n" , n_buffer, usr_buf[n_buffer].start ,buf.length); `:d\L H  
[Bj\h7 G  
zek>]l`!  
         !E^\)=E)P  
    } ~SI G0U8  
    return 0; 4W=fQx]  
} $&sV.fGu  
| NyANsI  
//initial camera device L#fK ,r8  
int init_camera_device(int fd) &td   
{ I(j$^DA.  
    //decive fuction, such as video input VdGpreRPC  
    struct v4l2_capability cap; 3teP6|K'g  
    //video standard,such as PAL,NTSC ViU5l*n;  
    struct v4l2_standard std; eKRE1DK  
    //frame format Lc(eY{CY  
    struct v4l2_format tv_fmt; kpMo7n  
    //check control /$9We8  
    struct v4l2_queryctrl query; sYB2{w   
    //detail control value Y4[oa?G  
    struct v4l2_fmtdesc fmt; E0.o/3Gw6  
    int ret; NMzq10M=6  
    //get the format of video supply Nl^u A  
    memset(&fmt, 0, sizeof(fmt)); |3>%(4 OS  
    fmt.index = 0; sAnb   
    //supply to image capture  }- wK  
    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; 9zm2}6r4  
    // show all format of supply |gU)6}V@  
    printf("Support format:\n"); LtV,djk  
    while(ioctl(fd, VIDIOC_ENUM_FMT, &fmt) == 0){ 2"WP>>b80  
        fmt.index++; wM}AWmH  
        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); .etG>tH  
    } tD,I7%|@  
    //check video decive driver capability 6_K7!?YG7  
    ret = ioctl(fd, VIDIOC_QUERYCAP, &cap); \5j#ad  
    if(ret < 0){ U#{(*)qr  
        perror("Fail to ioctl VIDEO_QUERYCAP"); 0 qW"b`9R  
        exit(EXIT_FAILURE); tjQ6[`  
    } h+Y>\Cxg  
gL`aLg_  
    //judge wherher or not to be a video-get device fh` }~ aQ  
    if(!(cap.capabilities & V4L2_BUF_TYPE_VIDEO_CAPTURE)) 4~2 9,  
    { '=J|IN7WT  
        printf("The Current device is not a video capture device\n"); &ViK9  
        exit(-1); FytGg[#]  
    } iu2O/l# r  
l nJ  
    //judge whether or not to supply the form of video stream YD0j&@.  
    if(!(cap.capabilities & V4L2_CAP_STREAMING)) EA z>`~  
    { m ;wj|@cF  
        printf("The Current device does not support streaming i/o\n"); 'Z)#SzY  
        exit(EXIT_FAILURE); l< HnPR/  
    } gUYTVp Vf  
0v``4z2Z  
    //set the form of camera capture data RFq=`/>dG  
]ZH6 .@|  
h?vny->uJ  
%v UUx+  
    tv_fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; w }8=sw  
V0n8fez b  
N|8^S  
#if 0 ]hRs -x  
    tv_fmt.fmt.pix.width = 640; {MUO25s02  
    tv_fmt.fmt.pix.height = 360; UG]x CkDS  
#else |)mUO:*  
,^jQBD4={  
    tv_fmt.fmt.pix.width = 1280; 4b}'W}  
    tv_fmt.fmt.pix.height = 960; 4tSh.qBht  
=6N=5JePB  
pp2 Jy{\d  
#endif mq4VwT  
,V)hV@Dk  
TN/&^/  
     [ C!m,4  
    tv_fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG; 21] K7  
    //V4L2_PIX_FMT_YUYV C;ME"4,(  
    tv_fmt.fmt.pix.field = V4L2_FIELD_INTERLACED; JB!*{{  
    if (ioctl(fd, VIDIOC_S_FMT, &tv_fmt)< 0) { aHPx'R  
        printf("VIDIOC_S_FMT\n"); u3DFgl3-7  
        exit(-1); ^P`I"T d  
        close(fd); p*JP='p  
    } zLPCWP.u  
    //initial video capture way(mmap) |T-Y tuy8  
    init_mmap(fd); W k"_lJ  
    return 0; rMJ4w['J=  
} V'9OGn2v  
9h<iw\ $'  
int open_camera_device() (1'sBm7F  
{ ^5+7D1>W%  
    int fd; @f-rS{  
    //open video device with block 5U*${  
    fd = open(FILE_VIDEO, O_RDWR /* required */ | O_NONBLOCK, 0);//打开设备 {@s6ly].  
    if(fd < 0){ L l,nt  
        perror(FILE_VIDEO); d8WEsQ+)A  
        exit(EXIT_FAILURE); UM'JK#P"  
    } z[JM ]Wy  
    return fd; YL[y3&K  
} !H @nAz  
D:(h^R0;  
int start_capture(int fd) E.yc"|n7l2  
{ o Y<vKs^  
    unsigned int i; ^SS9BQ*m  
    enum v4l2_buf_type type; 'NnmLM(oh  
    //place the kernel cache to a queue "eI">`!g  
    for(i = 0; i < n_buffer; i++){ ])WIw'L!  
        struct v4l2_buffer buf; 9y)}-TcSpY  
        memset(&buf, 0, sizeof(buf)); w_Z*X5u  
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; X4"[,:Tw  
        buf.memory = V4L2_MEMORY_MMAP; C+gu'hD  
        buf.index = i; [VOw:|Tt  
Bv`3T Af2  
        if(-1 == ioctl(fd, VIDIOC_QBUF, &buf)){ =[Tf9u QY  
            perror("Fail to ioctl 'VIDIOC_QBUF'"); _3gF~qr  
            exit(EXIT_FAILURE); w_q =mKu  
        } tgu fU  
    } <%oT}K\;  
oXqx]@7  
    //start capture data u?8e>a  
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE; Q\$cBSJC1  
    if(-1 == ioctl(fd, VIDIOC_STREAMON, &type)){ ralU9MN.  
        printf("i=%d.\n", i); E+eC #!&w  
        perror("VIDIOC_STREAMON"); [_p&,$z8[  
        close(fd); @'S !G"\  
        exit(EXIT_FAILURE); yMf["AvG  
    } a#,lf9M  
    return 0; +@#-S  
} H, O_l%  
q5~fU$ ,  
*\[GfTL  
int process_image(void *addr, int length) 3a,7lTUuB  
{ U,$^| Iz  
    int fd; ;p)fW/<  
    static int num = 0; p5=VGKp  
    char image_name[20]; lb#`f,r>  
$ZE"o`=7  
    printf("%s addr = 0x%x  length= %d \n" , __func__,addr,length); |Oe$)(`|h  
YZ+<+`Mz<  
    sprintf(image_name, JPG, num++); LpSd/_^b  
3 jay V  
    if((fd= open(image_name,O_CREAT|O_WRONLY)) == NULL){ Hd=!  
FYeUz$/  
         <}Rr C#uiA  
        printf("Fail to fopen"); 7o64|@'j  
        exit(EXIT_FAILURE); tPho4,x$  
         ^2um.`8  
    } Hk;) l3oB  
     }U7 ><I  
    write(fd,addr, length); las|ougLy  
    sync( ); v\ Xk6k  
    close(fd); uEkUK|  
     _ ;_NM5  
       return 0; }))JzrqAe  
   8'Ph/L,  
   K3^N_^H  
  } q9c:,k  
fmj-&6  
ySwvjP7f  
*a4nd_!  
~*h` ?A0  
O WVa&8O  
w">p 8  
bI~(<-S~K  
j:{d'OV  
X+T +y>e a  
(""1[XURQK  
/xRPQ|  
cC6W1K!  
int read_frame(int fd) d`;_~{sleR  
{ sX,oJIt  
    struct v4l2_buffer buf; 64OgE!  
    unsigned int i; 6uf+,F  
    memset(&buf, 0, sizeof(buf)); ;yO7!{_  
QNH5Cq;Y  
   printf("%s run   place 1 \n",__func__); Dh|8$(Jt  
PuhFbgxy  
     ^w XXx=Xf  
    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; ,#42ebGHR  
    buf.memory = V4L2_MEMORY_MMAP; jnuovM!x~  
    //put cache from queue *a7&v3X  
    if(-1 == ioctl(fd, VIDIOC_DQBUF,&buf)){ }*4K]3et$  
        perror("Fail to ioctl 'VIDIOC_DQBUF'"); iVt*N$iZ  
        exit(EXIT_FAILURE); wV;qc3  
    } =%YU~  
)MZQ\8,)]  
    assert(buf.index < n_buffer); 1dF=BR8  
    //read process space's data to a file dkC[Jt  
    printf("buf.index=%d\n",buf.index); DM%4 V|F"  
C{ {DZ*  
    process_image(usr_buf[buf.index].start, buf.bytesused); 37@_"  
yU~OfwQ  
:*"0o{ ie  
    printf("%s run   place 2 \n",__func__); <=*xwI&q  
AoEG%nT  
    if(-1 == ioctl(fd, VIDIOC_QBUF,&buf)){ E{*~>#+  
        perror("Fail to ioctl 'VIDIOC_QBUF'"); [*O#6Xu  
        exit(EXIT_FAILURE); j|&?BBa9  
    } eXI^9uH  
D^Bd>Ey4  
XTD _q  
    printf("%s run   place 3 \n",__func__); )IGE2k|  
     mB.kV Ve0  
    return 1; +1 H.5|  
} "]ow1{  
y8Bi5Ae,+1  
int mainloop(int fd) :cmfy6h]  
{ is%qG?,P  
    int count =20; -bK#&o,  
qTnfiYG}  
    while(count-- > 0) ) w.cCDL c  
    { ;6I{7[  
        for(;;) kn_%'7  
        { h1Ca9Z_  
            fd_set fds; `5;O|qRq  
            struct timeval tv; t+k"$zR  
            int r; 3VbQDPG  
_^'fp  
            printf("count = %d \n", count); lM C4j  
         ur-&- G^  
            FD_ZERO(&fds); +d6/*}ht  
            FD_SET(fd,&fds); 2Av3.u8%u  
&%`IPhbT  
            /*Timeout*/ KE+y'j#C3  
            tv.tv_sec = 200; '2a}1?  
            tv.tv_usec = 0; '+NmHu:q  
            r = select(fd + 1,&fds,NULL,NULL,&tv); MN|y5w}$u  
qtTys gv  
            if(-1 == r) ~wIVw}  
            { 6#O n .Q  
                if(EINTR == errno) 6pI =?g  
                    continue; LWc}j`Wd  
                perror("Fail to select"); 1`2n<qo  
                exit(EXIT_FAILURE); b5 YE4h8%  
            } 8zGe5Dn9  
FGBPhH% (8  
            if(0 == r) =Z iyT$p  
            { D Y($  
                fprintf(stderr,"select Timeout\n"); +/7UM x1  
                exit(-1); I@a7AuOw  
            } @0?Mwy!  
<wxI>T}b  
            if(read_frame(fd)) ;RW!l pGjP  
                break;  mQBq-;  
        } a_m P$4T  
    } ZebXcT ,41  
    return 0; BD[XP`[{  
} ~d ~$fR  
JJq= {;  
void stop_capture(int fd) s<|.vVi"  
{ s"p}>BjMIC  
    enum v4l2_buf_type type; Gk*Mx6|N  
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE; qiiX49}{  
    if(-1 == ioctl(fd,VIDIOC_STREAMOFF,&type)) *nluK  
    { Miqu  
        perror("Fail to ioctl 'VIDIOC_STREAMOFF'"); !E,$@mvd  
        exit(EXIT_FAILURE); 0tm%Kd  
    } +?[TH?2c+  
    return; B%Dy;zdWd/  
} }]N7CWy  
tfvX0J  
void close_camera_device(int fd) xIf,1g@Cq9  
{ -7*,}xV  
    unsigned int i; g4&zBn  
    for(i = 0;i < n_buffer; i++) kWc%u-_  
    { Lg[*P8wE  
        if(-1 == munmap(usr_buf.start,usr_buf.length)){ abuHu'73  
            exit(-1); x"K<@mR5G  
        } m'XzZmI  
    } ,Ww)>O+  
    free(usr_buf); 5Y#yz>B@ ]  
6 9ia #  
    if(-1 == close(fd)) v2G_p |+O  
    { Gn #5zx#l  
        perror("Fail to close fd"); Aga2 I#1r  
        exit(EXIT_FAILURE); }k.-xaj  
    } a9mLPP  
    return; 9XX&~GW/  
} F(^vD_G  
$`.7XD}  
int main() *4Y1((1k  
{ $GNN* WmHw  
c<wsWs 4V  
@bOhnd#W  
    int fd; "n," >  
    fd = open_camera_device(); LoSblV  
    init_camera_device(fd); [0El z@.C  
    start_capture(fd); fAm^-uq[  
    mainloop(fd); I!dA{INN  
    stop_capture(fd); |)* K#%j  
    close_camera_device(fd); 5'd$TC  
Q4Zuz)r*  
   0#<q]M?hW  
    return 0; 8{#W F#  
} CeSr~Ikg|  
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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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