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

[Thilo Borgmann]

Hi,

add %{localtime_ms} function to the drawtext filter. Same as %{localtime} but with additional millisecond part. 

-Thilo
-------------- next part --------------
From f3b32f3e2b01f50b4fa41f8432ccd5a5eeea1ec1 Mon Sep 17 00:00:00 2001
From: Kirill Pugin <ikir at fb.com>
Date: Tue, 8 Jun 2021 18:32:45 +0200
Subject: [PATCH] lavfi/drawtext: Add localtime_ms for millisecond precision

Suggested-By: ffmpeg at fb.com
---
 doc/filters.texi          |  4 ++++
 libavfilter/vf_drawtext.c | 20 +++++++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index 78faf767cf..bf073e0560 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -10953,6 +10953,10 @@ It can accept an argument: a strftime() format string.
 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 382d589e26..684f954236 100644
--- a/libavfilter/vf_drawtext.c
+++ b/libavfilter/vf_drawtext.c
@@ -53,6 +53,7 @@
 #include "libavutil/parseutils.h"
 #include "libavutil/timecode.h"
 #include "libavutil/time_internal.h"
+#include "libavutil/time.h"
 #include "libavutil/tree.h"
 #include "libavutil/lfg.h"
 #include "libavutil/detection_bbox.h"
@@ -1049,11 +1050,27 @@ static int func_strftime(AVFilterContext *ctx, AVBPrint *bp,
     struct tm tm;
 
     time(&now);
-    if (tag == 'L')
+    if (tag == 'L' || tag == 'M')
         localtime_r(&now, &tm);
     else
         tm = *gmtime_r(&now, &tm);
     av_bprint_strftime(bp, fmt, &tm);
+
+    if (tag == 'M') {
+        char ms[5] = {0};
+        // get time returns time since epoch in micro seconds, localtime_r would
+        // already take care of representing seconds part, so we need to get
+        // milliseconds, to do that we round up microseconds to seconds
+        // then convert seconds back to microseconds - this will drop microsecond
+        // precision, then compute difference between av_gettime result and
+        // rounded up sec -> usec representation and convert that to milliseconds
+        int64_t usecs      = av_gettime();
+        int64_t secs       = usecs / 1000000;
+        int64_t msec_delta = (usecs - secs * 1000000) / 1000;
+        snprintf(ms, 5, ".%03d", (int)msec_delta);
+        av_bprint_append_data(bp, ms, 4);
+    }
+
     return 0;
 }
 
@@ -1153,6 +1170,7 @@ static const struct drawtext_function {
     { "pts",       0, 3, 0,   func_pts      },
     { "gmtime",    0, 1, 'G', 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)