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

[Thilo Borgmann <thilo.borgmann@mail.de>]

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Am 14.01.22 um 14:17 schrieb "zhilizhao(赵志立)":
> 
> 
>> On Jan 14, 2022, at 8:14 PM, Thilo Borgmann <thilo.borgmann@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);

You know your printf format-string :)

Thanks, v6 attached.
-Thilo


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From 603a52a2bb86e558acdd754d8322e89e984dad08 Mon Sep 17 00:00:00 2001
From: Thilo Borgmann <thilo.borgmann@mail.de>
Date: Fri, 14 Jan 2022 18:38:14 +0100
Subject: [PATCH v6] lavfi/drawtext: Add localtime_ms for millisecond precision

Suggested-By: ffmpeg@fb.com
---
 doc/filters.texi          |  8 ++++++++
 libavfilter/vf_drawtext.c | 20 ++++++++++++++++++--
 2 files changed, 26 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.
 
+@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.
 
+@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..7e3771fdca 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 +1046,27 @@ 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) {
+            int len = seconds + 2 - fmt;
+            char *fmt_new = av_asprintf("%.*s.%03d%s", len, fmt, (int)(unow % 1000000) / 1000, seconds + 2);
+            av_bprint_strftime(bp, fmt_new, &tm);
+            return 0;
+        }
+    }
+
     av_bprint_strftime(bp, fmt, &tm);
     return 0;
 }
@@ -1152,7 +1166,9 @@ 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)


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