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lavfi/drawtext: Add %N for drawing fractions of a second

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Suggested-By: ffmpeg@fb.com
This commit is contained in:
Thilo Borgmann
2022-02-08 11:39:46 +01:00
parent 3706fb8f16
commit 74117abf0c
2 changed files with 71 additions and 3 deletions
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4
doc/filters.texi
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@@ -11431,10 +11431,14 @@ It can be used to add padding with zeros from the left.
@item gmtime
The time at which the filter is running, expressed in UTC.
It can accept an argument: a strftime() format string.
The format string is extended to support the variable @var{%[1-6]N}
which prints fractions of the second with optionally specified number of digits.
@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.
The format string is extended to support the variable @var{%[1-6]N}
which prints fractions of the second with optionally specified number of digits.
@item metadata
Frame metadata. Takes one or two arguments.

70
libavfilter/vf_drawtext.c
View File

@@ -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"
@@ -1045,15 +1046,78 @@ 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";
const char *fmt_begin = fmt;
int64_t unow;
time_t now;
struct tm tm;
const char *begin;
const char *tmp;
int len;
int div;
AVBPrint fmt_bp;
time(&now);
if (tag == 'L')
av_bprint_init(&fmt_bp, 0, AV_BPRINT_SIZE_UNLIMITED);
unow = av_gettime();
now = unow / 1000000;
if (tag == 'L' || tag == 'm')
localtime_r(&now, &tm);
else
tm = *gmtime_r(&now, &tm);
av_bprint_strftime(bp, fmt, &tm);
// manually parse format for %N (fractional seconds)
begin = fmt;
while ((begin = strchr(begin, '%'))) {
tmp = begin + 1;
len = 0;
// skip escaped "%%"
if (*tmp == '%') {
begin = tmp + 1;
continue;
}
// count digits between % and possible N
while (*tmp != '\0' && av_isdigit((int)*tmp)) {
len++;
tmp++;
}
// N encountered, insert time
if (*tmp == 'N') {
int num_digits = 3; // default show millisecond [1,6]
// if digit given, expect [1,6], warn & clamp otherwise
if (len == 1) {
num_digits = av_clip(*(begin + 1) - '0', 1, 6);
} else if (len > 1) {
av_log(ctx, AV_LOG_WARNING, "Invalid number of decimals for %%N, using default of %i\n", num_digits);
}
len += 2; // add % and N to get length of string part
div = pow(10, 6 - num_digits);
av_bprintf(&fmt_bp, "%.*s%0*d", (int)(begin - fmt_begin), fmt_begin, num_digits, (int)(unow % 1000000) / div);
begin += len;
fmt_begin = begin;
continue;
}
begin = tmp;
}
av_bprintf(&fmt_bp, "%s", fmt_begin);
if (!av_bprint_is_complete(&fmt_bp)) {
av_log(ctx, AV_LOG_WARNING, "Format string truncated at %u/%u.", fmt_bp.size, fmt_bp.len);
}
av_bprint_strftime(bp, fmt_bp.str, &tm);
av_bprint_finalize(&fmt_bp, NULL);
return 0;
}