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分享opencv如何读取遍历读取某个文件夹下的mp4文件
首先是文件的遍历不会写，再个是opencv如何才能读取mp4的视频信息放到一个对象里面，对象里包含帧数，宽高，。。。。等等信息
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赵4老师 2015-09-09
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搜能将mp4转为avi的命令行工具，使用system函数调用之。
shmilymdt 2015-09-09
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老师，那opencv好像只能读取avi的视频啊，有什么办法读取mp4的视频呢
赵4老师 2015-09-08
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那是因为你没遇到过“非法文件夹名或非法文件名或非法文件长度、非法文件日期、压缩文件、链接文件、稀疏文件……等各种意料之外的情况”
假正经的班长 2015-09-08
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遍历文件有现成的API，干嘛要用这种方式，解析起来麻烦，而且还依赖输出的格式变化。
赵4老师 2015-09-08
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system("dir /b /a-d c:\\*.* >d:\\allfiles.txt");
//读文件d:\\allfiles.txt的内容即C:\\下所有文件的名字
system("dir /b /a-d /s c:\\*.* >d:\\allfilesinsub.txt");
//读文件d:\\allfilesinsub.txt的内容即C:\\下所有文件的名字包含子目录
system("dir /b /ad c:\\*.* >d:\\alldirs.txt");
//读文件d:\\alldirs.txt的内容即C:\\下所有子目录的名字
请记住，能用shell命令获取文件、文件夹信息或者操作文件、文件夹最好用shell命令获取或者操作，而不要用各种API获取或者操作，因为当遇到非法文件夹名或非法文件名或非法文件长度、非法文件日期、压缩文件、链接文件、稀疏文件……等各种意料之外的情况时，API会处理的不全面或陷入死循环，而shell命令不会。
赵4老师 2015-09-08
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仅供参考：
//将c:\\tmp文件夹下的所有文件的内容全部放到用malloc分配的内存中
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <io.h>
struct FB {
char fn[256];
size_t fl;
char *b;
struct FB *next;
struct FB *prev;
} *fh,*fb,*ft;
char ln[256];
char fpn[256];
FILE *af;
FILE *f;
int L,n;
int main() {
system("dir /b /a-d c:\\tmp\\*.* >c:\\allfn.txt");
af=fopen("c:\\allfn.txt","r");
if (NULL==af) {
printf("Can not open file c:\\allfn.txt!\n");
return 1;
}
fh=NULL;
fb=NULL;
n=0;
while (1) {
if (NULL==fgets(ln,256,af)) break;
L=strlen(ln);
if ('\n'==ln[L-1]) ln[L-1]=0;
printf("read %s\n",ln);
strcpy(fpn,"c:\\tmp\\");
strcat(fpn,ln);
ft=(struct FB *)malloc(sizeof(struct FB));
if (NULL==ft) {
printf("Can not malloc ft!\n");
fclose(af);
return 2;//之前的malloc在main退出后由操作系统自动free
}
printf("ft[%d]==%p\n",n,ft);
strcpy(ft->fn,fpn);
f=fopen(fpn,"rb");
if (NULL==f) {
printf("Can not open file %s!\n",fpn);
fclose(af);
return 3;//之前的malloc在main退出后由操作系统自动free
}
ft->fl=_filelength(fileno(f));
ft->b=malloc(ft->fl);
if (NULL==ft->b) {
printf("Can not malloc ft->b!\n");
fclose(f);
fclose(af);
return 4;//之前的malloc在main退出后由操作系统自动free
}
printf("ft[%d]->b==%p\n",n,ft->b);
if (ft->fl!=fread(ft->b,1,ft->fl,f)) {
printf("fread error!\n");
fclose(f);
fclose(af);
return 5;//之前的malloc在main退出后由操作系统自动free
}
fclose(f);
ft->next=NULL;
if (NULL==fh) {
ft->prev=NULL;
fh=ft;
} else {
fb->next=ft;
ft->prev=fb;
}
fb=ft;
n++;
}
fclose(af);
printf("-----list-----\n");
for (ft=fh;NULL!=ft;ft=ft->next) {
printf("%8d %s\n",ft->fl,ft->fn);
if (NULL!=ft) fb=ft;
}
printf("-----free-----\n");
n--;
if (NULL!=fh) {
for (ft=fb->prev;NULL!=ft;ft=ft->prev) {
if (NULL!=ft->next->b) {
printf("ft[%d]->b==%p\n",n,ft->next->b);
free(ft->next->b);
}
if (NULL!=ft->next) {
printf("ft[%d]==%p\n",n,ft->next);
free(ft->next);
}
n--;
}
if (NULL!=fh->b) {
printf("ft[0]->b==%p\n",fh->b);
free(fh->b);
}
printf("ft[0]==%p\n",fh);
free(fh);
}
return 0;
}
//C:\tmp\tmp\Debug>dir /a-d c:\tmp
// 驱动器 C 中的卷是 C_HD5_1
// 卷的序列号是 1817-D526
//
// c:\tmp 的目录
//
//找不到文件
//
//C:\tmp\tmp\Debug>tmp
//找不到文件
//-----list-----
//-----free-----
//
//C:\tmp\tmp\Debug>dir /a-d c:\tmp
// 驱动器 C 中的卷是 C_HD5_1
// 卷的序列号是 1817-D526
//
// c:\tmp 的目录
//
//2011-06-30 18:04 44,840 my_c.rar
//2011-06-30 17:18 1,036 err.frm
//2011-06-30 14:32 14,243 出租.txt
//2011-06-28 12:08 23,681 MSDN98书签.txt
// 4 个文件 83,800 字节
// 0 个目录 17,041,870,848 可用字节
//
//C:\tmp\tmp\Debug>tmp
//read my_c.rar
//ft[0]==00421800
//ft[0]->b==00520068
//read err.frm
//ft[1]==00421670
//ft[1]->b==0052AFC0
//read 出租.txt
//ft[2]==00421530
//ft[2]->b==00378F28
//read MSDN98书签.txt
//ft[3]==004213F0
//ft[3]->b==0052B3F8
//-----list-----
// 44840 c:\tmp\my_c.rar
// 1036 c:\tmp\err.frm
// 14243 c:\tmp\出租.txt
// 23681 c:\tmp\MSDN98书签.txt
//-----free-----
//ft[3]->b==0052B3F8
//ft[3]==004213F0
//ft[2]->b==00378F28
//ft[2]==00421530
//ft[1]->b==0052AFC0
//ft[1]==00421670
//ft[0]->b==00520068
//ft[0]==00421800
//
//C:\tmp\tmp\Debug>
赵4老师 2015-09-08
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Linux下opendir()、readdir()和closedir()这三个函数主要用来遍历目录
赵4老师 2015-09-08
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FindFirstFile
The FindFirstFile function searches a directory for a file whose name matches the specified filename. FindFirstFile examines subdirectory names as well as filenames.
HANDLE FindFirstFile(
LPCTSTR lpFileName, // pointer to name of file to search for
LPWIN32_FIND_DATA lpFindFileData
// pointer to returned information
);
Parameters
lpFileName
Windows 95: Pointer to a null-terminated string that specifies a valid directory or path and filename, which can contain wildcard characters (* and ?). This string must not exceed MAX_PATH characters.
Windows NT: Pointer to a null-terminated string that specifies a valid directory or path and filename, which can contain wildcard characters (* and ?).
There is a default string size limit for paths of MAX_PATH characters. This limit is related to how the FindFirstFile function parses paths. An application can transcend this limit and send in paths longer than MAX_PATH characters by calling the wide (W) version of FindFirstFile and prepending "\\?\" to the path. The "\\?\" tells the function to turn off path parsing; it lets paths longer than MAX_PATH be used with FindFirstFileW. However, each component in the path cannot be more than MAX_PATH characters long. This also works with UNC names. The "\\?\" is ignored as part of the path. For example, "\\?\C:\myworld\private" is seen as "C:\myworld\private", and "\\?\UNC\bill_g_1\hotstuff\coolapps" is seen as "\\bill_g_1\hotstuff\coolapps".
lpFindFileData
Pointer to the WIN32_FIND_DATA structure that receives information about the found file or subdirectory. The structure can be used in subsequent calls to the FindNextFile or FindClose function to refer to the file or subdirectory.
Return Values
If the function succeeds, the return value is a search handle used in a subsequent call to FindNextFile or FindClose.
If the function fails, the return value is INVALID_HANDLE_VALUE. To get extended error information, call GetLastError.
Remarks
The FindFirstFile function opens a search handle and returns information about the first file whose name matches the specified pattern. Once the search handle is established, you can use the FindNextFile function to search for other files that match the same pattern. When the search handle is no longer needed, close it by using the FindClose function.
This function searches for files by name only; it cannot be used for attribute-based searches.
QuickInfo
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winbase.h.
Import Library: Use kernel32.lib.
Unicode: Implemented as Unicode and ANSI versions on Windows NT.
See Also
File I/O Overview, File Functions, FindClose, FindNextFile, GetFileAttributes, SetFileAttributes, WIN32_FIND_DATA
shmilymdt 2015-09-08
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遍历文件有现成的API，干嘛要用这种方式，解析起来麻烦，而且还依赖输出的格式变化。
[/quote]用API的你会写么？我表示不会写
shmilymdt 2015-09-08
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看不懂。。。
欧阳春晖 2015-09-08
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没看懂什么意思？
