[FFmpeg-devel] Image sequence file names

[Michael Niedermayer]

Hi robert

On Wed, Aug 31, 2011 at 10:43:17PM +0200, Robert Petka wrote:
> Dňa 31. 8. 2011 0:59, Michael Niedermayer  wrote / napísal(a):
>> On Wed, Aug 31, 2011 at 12:08:56AM +0200, Robert Petka wrote:
>> when you do, please write the implementation so as to avoid known
>> bugs in dirname.
>>
>> the manpage says (dunno if you have the manpages on msys)
>>   BUGS
>>         In the glibc implementation of the POSIX versions of these functions they modify their argument, and segfault when called with a static string like "/usr/".  Before glibc 2.2.1, the  glibc  version
>>         of dirname() did not correctly handle pathnames with trailing '/' characters, and generated a segfault if given a NULL argument.
>>
>>
>> [...]
>>
>>
>>
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> Here's the modified patch file with dirname usage.
>
> Robert

>  img2.c |   71 +++++++++++++++++++++++++++++++++++++++++++++++++++++++----------
>  1 file changed, 61 insertions(+), 10 deletions(-)
> 3d2e9a948755cdeb1b940f8f86381bb5982ee492  image_range.diff
> diff --git a/libavformat/img2.c b/libavformat/img2.c
> index 77145cb..2b2c37c 100644
> --- a/libavformat/img2.c
> +++ b/libavformat/img2.c
> @@ -30,6 +30,10 @@
>  #include "avio_internal.h"
>  #include "internal.h"
>  #include <strings.h>
> +#include <stdio.h>
> +#include <sys/types.h>
> +#include <dirent.h>
> +#include <libgen.h>
>  
>  typedef struct {
>      const AVClass *class;  /**< Class for private options. */
> @@ -133,27 +137,74 @@ static enum CodecID av_str2id(const IdStrMap *tags, const char *str)
>      return CODEC_ID_NONE;
>  }
>  
> +static int get_index_for_file(const char* path)
> +{
> +    int i, last_digit, first_digit, index;
> +
> +    first_digit = -1;
> +    last_digit = -1;
> +
> +    for (i=strlen(path)-1;i>=0;i--) {
> +        if (last_digit == -1) {
> +            if (isdigit(path[i]))
> +                last_digit = i;
> +        } else {
> +            if (isdigit(path[i])) {
> +                first_digit = i;
> +            } else
> +                break;
> +        }
> +    }
> +
> +    index = -1;
> +    if (first_digit != -1) {
> +        sscanf(path + first_digit,"%d",&index);
> +    }
> +
> +    return index;
> +}
> +
>  /* return -1 if no image found */
>  static int find_image_range(int *pfirst_index, int *plast_index,
>                              const char *path)
>  {
>      char buf[1024];
>      int range, last_index, range1, first_index;
> +    DIR *dp = 0;
> +    struct dirent *ep = 0;
> +    char dirPath[MAX_PATH], pathCopy[MAX_PATH];
> +    char *directory = 0;
>  
>      /* find the first image */
> -    for(first_index = 0; first_index < 5; first_index++) {
> -        if (av_get_frame_filename(buf, sizeof(buf), path, first_index) < 0){
> -            *pfirst_index =
> -            *plast_index = 1;
> -            if (avio_check(buf, AVIO_FLAG_READ) > 0)
> -                return 0;
> -            return -1;
> +    first_index = -1;
> +
> +    /* get files directory */
> +    av_strlcpy(pathCopy, path, FFMIN(sizeof(pathCopy),strlen(path) + 1));
> +    directory = dirname(pathCopy);
> +    av_strlcpy(dirPath, directory, FFMIN(sizeof(dirPath),strlen(directory) + 1));

the FFMIN and strlen seem unneeded


> +
> +    dp = opendir (dirPath);

this code should only be run when the underlaying protocol is file,
it should for example not be used with http://


> +    if (dp) {

> +        int min_index;
> +        min_index = INT_MAX;

could be merged


> +
> +        while (ep = readdir (dp)) {
> +            int file_index;
> +            file_index = get_index_for_file(ep->d_name);
> +
> +            if (file_index != -1) {
> +                min_index = FFMIN(min_index, file_index);
> +            }

if the "fail" value is INT_MAX instead of -1 then the if() is unneeded


[...]


-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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