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

"zhilizhao(赵志立)" quinkblack at foxmail.com
Fri Jan 14 15:17:49 EET 2022



> On Jan 14, 2022, at 8:14 PM, Thilo Borgmann <thilo.borgmann at mail.de> wrote:
> 
> Am 06.01.22 um 12:27 schrieb Thilo Borgmann:
>> 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.


> +    if (tag == 'M' || tag == 'm') {
> +        char *seconds = av_stristr(fmt, "%S");
> +        if (seconds) {
> +            seconds += 2;
> +            int len = seconds - fmt + 1;
> +            char *tmp = av_malloc(len);
> +            av_strlcpy(tmp, fmt, len);

Firstly, mixed variable declaration and statements.

Secondly, I think you don’t need ’tmp’, something like

av_asprintf(“%.*s.%03d%s", len, fmt, (int)(unow % 1000000) / 1000, seconds);

> +
> +            char *fmt_new = av_asprintf("%s.%03d%s", tmp, (int)(unow % 1000000) / 1000, seconds);
> +            av_bprint_strftime(bp, fmt_new, &tm);
> +
> +            av_freep(&tmp);
> +            av_freep(&fmt_new);
> +
> +            return 0;
> +        }
> +    }


> 
> Ping ^
> 
> -Thilo
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