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lavf/segment: add reset_timestamps option 

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
View File

@ -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
View File

@ -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, \