[FFmpeg-devel] [PATCH] Add support for drawing PTS in HHMMSSms format to vf_drawtext

[Nicolas George]

Le quintidi 5 floréal, an CCXXII, hjiodjf 97xgw46 a écrit :
> Thank you for pointing this out. I've simplified my patch and
> converted it to use an expansion function.

Thanks. A few more comments.

> From 3fb6b22d59b5216717907f591e1b57f0bad80c7d Mon Sep 17 00:00:00 2001
> From: tue46wsdgxfjrt <jfbvxt at gmail.com>
> Date: Wed, 19 Mar 2014 13:26:11 -0700
> Subject: [PATCH 2/2] Add support for drawing wall clock timestamps to
>  vf_drawtext.
> 
> ---
>  doc/filters.texi          |  3 +++
>  libavfilter/vf_drawtext.c | 25 +++++++++++++++++++++++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/doc/filters.texi b/doc/filters.texi
> index e943923..6c437e0 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -3852,6 +3852,9 @@ A 1 character description of the current picture type.
>  @item pts
>  The timestamp of the current frame, in seconds, with microsecond accuracy.
>  
> + at item timestamp

> +The timestamp of the current frame as HH:MM:SS.ms, with millisecond accuracy.

Maybe "HH:MM:SS.mmm", to make more obvious that millisecond means three
digits.

> +
>  @end table
>  
>  @subsection Examples
> diff --git a/libavfilter/vf_drawtext.c b/libavfilter/vf_drawtext.c
> index 280abb8..973f811 100644
> --- a/libavfilter/vf_drawtext.c
> +++ b/libavfilter/vf_drawtext.c
> @@ -700,6 +700,30 @@ static int func_pts(AVFilterContext *ctx, AVBPrint *bp,
>      return 0;
>  }
>  
> +static int func_timestamp(AVFilterContext *ctx, AVBPrint *bp,
> +                          char *fct, unsigned argc, char **argv, int tag)
> +{
> +    DrawTextContext *s = ctx->priv;
> +    int64_t ts = 0;
> +    int hh, mm, ss, ms;
> +

> +    if (argc > 0) {
> +        ts += round(atof(argv[0]) * 1000);
> +    }

I assume this means that %{timestamp:42} will shift the timestamps by 42
seconds, but it is not explained in the doc. And it is a bit strange to have
that feature for timestamp and not pts.

Also, maybe use av_parse_time(), that would avoid floats completely.

> +    ts += round(s->var_values[VAR_T] * 1000);

The rest of the code seems to handle the NOPTS case, so I suppose it should
be handled here too.

> +
> +    hh = ts / (3600 * 1000);
> +    ts = ts % (3600 * 1000);
> +    mm = ts / (60 * 1000);
> +    ts = ts % (60 * 1000);
> +    ss = ts / 1000;
> +    ts = ts % 1000;
> +    ms = ts;
> +
> +    av_bprintf(bp, "%02d:%02d:%02d.%03d", hh, mm, ss, ms);

Also, negative case is not handled gracefully.

> +    return 0;
> +}
> +
>  static int func_frame_num(AVFilterContext *ctx, AVBPrint *bp,
>                            char *fct, unsigned argc, char **argv, int tag)
>  {
> @@ -773,6 +797,7 @@ static const struct drawtext_function {
>      { "e",         1, 1, 0,   func_eval_expr },
>      { "pict_type", 0, 0, 0,   func_pict_type },
>      { "pts",       0, 0, 0,   func_pts      },

> +    { "timestamp", 0, 1, 0,   func_timestamp },

I find the name "timestamp" a big vague, but I have no better proposal than
"hmspts".

>      { "gmtime",    0, 1, 'G', func_strftime },
>      { "localtime", 0, 1, 'L', func_strftime },
>      { "frame_num", 0, 0, 0,   func_frame_num },

I have an alternate proposal. Please comment. And tel me if you want to be
co-credited.

Regards,

-- 
  Nicolas George
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