[FFmpeg-devel] [PATCH v2] lavfi/drawtext: Add localtime_ms for millisecond precision

[James Almer]

On 1/6/2022 8:27 AM, Thilo Borgmann wrote:
> Am 03.01.22 um 16:22 schrieb Thilo Borgmann:
>> Am 29.12.21 um 12:46 schrieb Nicolas George:
>>> "zhilizhao(赵志立)" (12021-12-29):
>>>> How about add a restriction like this:
>>>>
>>>> if (format.endsWith(“%S"))
>>>>      enable the feature
>>>> else
>>>>      warning message
>>>>
>>>> It’s a useful feature, it shouldn't create unexpected results, but
>>>> doesn’t need to support every use case.
>>>
>>> I would not oppose it, but I find it inelegant, especially because it
>>> requires a different expansion function, localtime_ms instead of
>>> localtime.
>>>
>>> What about this: with the original function "localtime", if the format
>>> ends in "%3N", then append the millisecond. It can later be expanded to
>>> support %xN at any place in the format for any value of x.
>>
>> I think best will be to scan the format string for %S and extend it there with .ms part before expanding the rest of it, not? Shouldn't be too expensive for the filter.
>>
>> Just need to find time to actually implement it.
> 
> Like v5 as attached.
> 
> Thanks,
> Thilo


> From c7f7c7a1cedc4ccc51977fc92645e1131608ac95 Mon Sep 17 00:00:00 2001
> From: Thilo Borgmann <thilo.borgmann at mail.de>
> Date: Thu, 6 Jan 2022 12:24:46 +0100
> Subject: [PATCH v5] lavfi/drawtext: Add localtime_ms for millisecond precision
> 
> Suggested-By: ffmpeg at fb.com
> ---
>  doc/filters.texi          |  8 ++++++++
>  libavfilter/vf_drawtext.c | 28 ++++++++++++++++++++++++++--
>  2 files changed, 34 insertions(+), 2 deletions(-)
> 
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 05d4b1a56e..967021e48b 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -11379,10 +11379,18 @@ It can be used to add padding with zeros from the left.
>  The time at which the filter is running, expressed in UTC.
>  It can accept an argument: a strftime() format string.
>  
> + at item gmtime_ms
> +Same as @code{gmtime} but with millisecond precision.
> +It can accept an argument: a strftime() format string.
> +
>  @item localtime
>  The time at which the filter is running, expressed in the local time zone.
>  It can accept an argument: a strftime() format string.
>  
> + at item localtime_ms
> +Same as @code{localtime} but with millisecond precision.
> +It can accept an argument: a strftime() format string.
> +
>  @item metadata
>  Frame metadata. Takes one or two arguments.
>  
> diff --git a/libavfilter/vf_drawtext.c b/libavfilter/vf_drawtext.c
> index 2a88692cbd..723473f299 100644
> --- a/libavfilter/vf_drawtext.c
> +++ b/libavfilter/vf_drawtext.c
> @@ -51,6 +51,7 @@
>  #include "libavutil/opt.h"
>  #include "libavutil/random_seed.h"
>  #include "libavutil/parseutils.h"
> +#include "libavutil/time.h"
>  #include "libavutil/timecode.h"
>  #include "libavutil/time_internal.h"
>  #include "libavutil/tree.h"
> @@ -1045,14 +1046,35 @@ static int func_strftime(AVFilterContext *ctx, AVBPrint *bp,
>                           char *fct, unsigned argc, char **argv, int tag)
>  {
>      const char *fmt = argc ? argv[0] : "%Y-%m-%d %H:%M:%S";
> +    int64_t unow;
>      time_t now;
>      struct tm tm;
>  
> -    time(&now);
> -    if (tag == 'L')
> +    unow = av_gettime();
> +    now  = unow / 1000000;
> +    if (tag == 'L' || tag == 'm')
>          localtime_r(&now, &tm);
>      else
>          tm = *gmtime_r(&now, &tm);
> +
> +    if (tag == 'M' || tag == 'm') {
> +        char *seconds = av_stristr(fmt, "%S");
> +        if (seconds) {
> +            seconds += 2;
> +            int len = seconds - fmt + 1;

Should be size_t. Also, mixed declarations and code.

> +            char *tmp = av_malloc(len);
> +            av_strlcpy(tmp, fmt, len);
> +
> +            char *fmt_new = av_asprintf("%s.%03d%s", tmp, (int)(unow % 1000000) / 1000, seconds);

Same.

> +            av_bprint_strftime(bp, fmt_new, &tm);
> +
> +            av_freep(&tmp);
> +            av_freep(&fmt_new);
> +
> +            return 0;
> +        }
> +    }
> +
>      av_bprint_strftime(bp, fmt, &tm);
>      return 0;
>  }
> @@ -1152,7 +1174,9 @@ static const struct drawtext_function {
>      { "pict_type", 0, 0, 0,   func_pict_type },
>      { "pts",       0, 3, 0,   func_pts      },
>      { "gmtime",    0, 1, 'G', func_strftime },
> +    { "gmtime_ms", 0, 1, 'M', func_strftime },
>      { "localtime", 0, 1, 'L', func_strftime },
> +    { "localtime_ms", 0, 1, 'm', func_strftime },
>      { "frame_num", 0, 0, 0,   func_frame_num },
>      { "n",         0, 0, 0,   func_frame_num },
>      { "metadata",  1, 2, 0,   func_metadata },
> -- 
> 2.20.1 (Apple Git-117)
>