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5df901ffa5
av_ts_make_time_string() used "%.6g" format, but this format was losing precision even when the timestamp to be printed was not that large. For example for 3 hours (10800) seconds, only 1 decimal digit was printed, which made this format inaccurate when it was used in e.g. the silencedetect filter. Other detection filters printing timestamps had similar issues. Also time base parameter of the function was *AVRational instead of AVRational. Resolve these problems by introducing a new function, av_ts_make_time_string2(). We change the used format to "%.*f", use a precision of 6, except when printing values near 0, in which case we calculate the precision dynamically to aim for a similar precision in normal form as with %.6g. No longer using scientific representation can make parsing the timestamp easier for the users, we can safely do this because the theoretical maximum of INT64_MAX*INT32_MAX still fits into the string buffer in normal form. We somewhat imitate %g by trimming ending zeroes and the potential decimal point characters. In order not to trim "inf" as well, we assume that the decimal point string does not contain the letter "f". Note that depending on printf %f implementation, we might trim "infinity" to "inf". Thanks for Allan Cady for bringing up this issue. Signed-off-by: Marton Balint <cus@passwd.hu>
37 lines
1.4 KiB
C
37 lines
1.4 KiB
C
/*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "timestamp.h"
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char *av_ts_make_time_string2(char *buf, int64_t ts, AVRational tb)
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{
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if (ts == AV_NOPTS_VALUE) {
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snprintf(buf, AV_TS_MAX_STRING_SIZE, "NOPTS");
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} else {
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double val = av_q2d(tb) * ts;
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double log = floor(log10(fabs(val)));
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int precision = (isfinite(log) && log < 0) ? -log + 5 : 6;
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int last = snprintf(buf, AV_TS_MAX_STRING_SIZE, "%.*f", precision, val);
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last = FFMIN(last, AV_TS_MAX_STRING_SIZE - 1) - 1;
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for (; last && buf[last] == '0'; last--);
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for (; last && buf[last] != 'f' && (buf[last] < '0' || buf[0] > '9'); last--);
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buf[last + 1] = '\0';
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}
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return buf;
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}
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