[FFmpeg-devel] [PATCH ] libavformat/utils : add timestamp option in av_get_frame_filename

[Nicolas George]

Le nonidi 29 vendémiaire, an CCXXI, Tom Fonck a écrit :
> I added an option to use the current time in the filename output
> instead of a counter.
> 
> If you think it isn't useful for others (or the code is bad), no problem.

It is probably useful, indded. Thanks for the patch.

> 
> Regards,
> 
> Tom
> 

> >From 71bb60aee7513e0fb22f6252aec85a7fe572f915 Mon Sep 17 00:00:00 2001
> From: Tom Fonck <tomf at besite.be>
> Date: Sat, 20 Oct 2012 14:32:05 +0200
> Subject: [PATCH 1/1] libavformat/utils : add timestamp option in av_get_frame_filename
> 
> ---
>  libavformat/utils.c |   16 ++++++++++++++++
>  1 files changed, 16 insertions(+), 0 deletions(-)
> 
> diff --git a/libavformat/utils.c b/libavformat/utils.c
> index be1be00..4477b06 100644
> --- a/libavformat/utils.c
> +++ b/libavformat/utils.c
> @@ -21,6 +21,7 @@
>  
>  /* #define DEBUG */
>  
> +#include <sys/time.h>
>  #include "avformat.h"
>  #include "avio_internal.h"
>  #include "internal.h"
> @@ -3409,6 +3410,8 @@ int av_get_frame_filename(char *buf, int buf_size,
>      const char *p;
>      char *q, buf1[20], c;
>      int nd, len, percentd_found;
> +    const struct timeval tim;

> +    long int timestamp;

long is almost never an adequate type. In this particular case, it is not:
on 32 bits architectures, long is almost always 32 bits, and your
computations will overflow immediately.

>  
>      q = buf;
>      p = path;
> @@ -3429,6 +3432,19 @@ int av_get_frame_filename(char *buf, int buf_size,
>              switch(c) {
>              case '%':
>                  goto addchar;
> +            case 't':
> +                if (percentd_found)
> +                    goto fail;
> +                percentd_found = 1;
> +                gettimeofday(&tim, NULL);
> +                timestamp = (tim.tv_sec * 1000000) + tim.tv_usec;

There is an av_gettime that already does that, without the portability
issues.

But I fail to see the use of that: a frame name based on the frame timestamp
(PTS) seems useful, but based on the physical time the frame happens to
arrive to the muxer I do not see.

> +                snprintf(buf1, sizeof(buf1), "%lu", timestamp);
> +                len = strlen(buf1);
> +                if ((q - buf + len) > buf_size - 1)
> +                    goto fail;
> +                memcpy(q, buf1, len);
> +                q += len;
> +                break;
>              case 'd':
>                  if (percentd_found)
>                      goto fail;

Regards,

-- 
  Nicolas George
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