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lavf/segment: add reset_timestamps option

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The new options reset the timestamps at each new segment, so that the
generated segments will have timestamps starting close to 0.

It is meant to address trac ticket #1425.
This commit is contained in:
Stefano Sabatini 2012-11-29 13:45:50 +01:00
parent 22e4988673
commit 8e9056559e
3 changed files with 33 additions and 1 deletions
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7
doc/muxers.texi
View File

@ -598,8 +598,15 @@ the specified time and the time set by @var{force_key_frames}.
@item segment_times @var{times}
Specify a list of split points. @var{times} contains a list of comma
separated duration specifications, in increasing order.
@item segment_wrap @var{limit}
Wrap around segment index once it reaches @var{limit}.
@item reset_timestamps @var{1|0}
Reset timestamps at the begin of each segment, so that each segment
will start with near-zero timestamps. It is meant to ease the playback
of the generated segments. May not work with some combinations of
muxers/codecs. It is set to @code{0} by default.
@end table
Some examples follow.

25
libavformat/segment.c
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@ -34,6 +34,7 @@
#include "libavutil/avstring.h"
#include "libavutil/parseutils.h"
#include "libavutil/mathematics.h"
#include "libavutil/timestamp.h"
typedef enum {
LIST_TYPE_UNDEFINED = -1,
@ -71,8 +72,11 @@ typedef struct {
int64_t time_delta;
int individual_header_trailer; /**< Set by a private option. */
int write_header_trailer; /**< Set by a private option. */
int reset_timestamps; ///< reset timestamps at the begin of each segment
int has_video;
double start_time, end_time;
int64_t start_pts, start_dts;
} SegmentContext;
static void print_csv_escaped_str(AVIOContext *ctx, const char *str)
@ -467,6 +471,7 @@ static int seg_write_packet(AVFormatContext *s, AVPacket *pkt)
/* if the segment has video, start a new segment *only* with a key video frame */
if ((st->codec->codec_type == AVMEDIA_TYPE_VIDEO || !seg->has_video) &&
pkt->pts != AV_NOPTS_VALUE &&
av_compare_ts(pkt->pts, st->time_base,
end_pts-seg->time_delta, AV_TIME_BASE_Q) >= 0 &&
pkt->flags & AV_PKT_FLAG_KEY) {
@ -485,11 +490,29 @@ static int seg_write_packet(AVFormatContext *s, AVPacket *pkt)
oc = seg->avf;
seg->start_time = (double)pkt->pts * av_q2d(st->time_base);
seg->start_pts = av_rescale_q(pkt->pts, st->time_base, AV_TIME_BASE_Q);
seg->start_dts = pkt->dts != AV_NOPTS_VALUE ?
av_rescale_q(pkt->dts, st->time_base, AV_TIME_BASE_Q) : seg->start_pts;
} else if (pkt->pts != AV_NOPTS_VALUE) {
seg->end_time = FFMAX(seg->end_time,
(double)(pkt->pts + pkt->duration) * av_q2d(st->time_base));
}
if (seg->reset_timestamps) {
av_log(s, AV_LOG_DEBUG, "start_pts:%s pts:%s start_dts:%s dts:%s",
av_ts2timestr(seg->start_pts, &AV_TIME_BASE_Q), av_ts2timestr(pkt->pts, &st->time_base),
av_ts2timestr(seg->start_dts, &AV_TIME_BASE_Q), av_ts2timestr(pkt->dts, &st->time_base));
/* compute new timestamps */
if (pkt->pts != AV_NOPTS_VALUE)
pkt->pts -= av_rescale_q(seg->start_pts, AV_TIME_BASE_Q, st->time_base);
if (pkt->dts != AV_NOPTS_VALUE)
pkt->dts -= av_rescale_q(seg->start_dts, AV_TIME_BASE_Q, st->time_base);
av_log(s, AV_LOG_DEBUG, " -> pts:%s dts:%s\n",
av_ts2timestr(pkt->pts, &st->time_base), av_ts2timestr(pkt->dts, &st->time_base));
}
ret = ff_write_chained(oc, pkt->stream_index, pkt, s);
fail:
@ -548,8 +571,10 @@ static const AVOption options[] = {
{ "segment_time_delta","set approximation value used for the segment times", OFFSET(time_delta_str), AV_OPT_TYPE_STRING, {.str = "0"}, 0, 0, E },
{ "segment_times", "set segment split time points", OFFSET(times_str),AV_OPT_TYPE_STRING,{.str = NULL}, 0, 0, E },
{ "segment_wrap", "set number after which the index wraps", OFFSET(segment_idx_wrap), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, E },
{ "individual_header_trailer", "write header/trailer to each segment", OFFSET(individual_header_trailer), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, E },
{ "write_header_trailer", "write a header to the first segment and a trailer to the last one", OFFSET(write_header_trailer), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, E },
{ "reset_timestamps", "reset timestamps at the begin of each segment", OFFSET(reset_timestamps), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, E },
{ NULL },
};

2
libavformat/version.h
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@ -31,7 +31,7 @@
#define LIBAVFORMAT_VERSION_MAJOR 54
#define LIBAVFORMAT_VERSION_MINOR 49
#define LIBAVFORMAT_VERSION_MICRO 100
#define LIBAVFORMAT_VERSION_MICRO 101
#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
LIBAVFORMAT_VERSION_MINOR, \