From: Vishwanath Dixit <vdi...@akamai.com>
availability time of Nth segment = availabilityStartTime + (N*segment duration)
- availabilityTimeOffset.
This field helps to reduce the latency by about a segment duration in streaming
mode.
---
libavformat/dashenc.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
index b62cb3e..d20bdba 100644
--- a/libavformat/dashenc.c
+++ b/libavformat/dashenc.c
@@ -85,6 +85,7 @@ typedef struct OutputStream {
char filename[1024];
char full_path[1024];
char temp_path[1024];
+ int64_t chunk_duration;
} OutputStream;
typedef struct DASHContext {
@@ -343,8 +344,12 @@ static void output_segment_list(OutputStream *os,
AVIOContext *out, AVFormatCont
if (c->use_template) {
int timescale = c->use_timeline ? os->ctx->streams[0]->time_base.den :
AV_TIME_BASE;
avio_printf(out, "\t\t\t\t<SegmentTemplate timescale=\"%d\" ",
timescale);
- if (!c->use_timeline)
+ if (!c->use_timeline) {
avio_printf(out, "duration=\"%d\" ", c->seg_duration);
+ if (c->streaming && os->chunk_duration)
+ avio_printf(out, "availabilityTimeOffset=\"%.3f\" ",
+ ((double) c->seg_duration - os->chunk_duration) /
AV_TIME_BASE);
+ }
avio_printf(out, "initialization=\"%s\" media=\"%s\"
startNumber=\"%d\">\n", c->init_seg_name, c->media_seg_name, c->use_timeline ?
start_number : 1);
if (c->use_timeline) {
int64_t cur_time = 0;
@@ -1283,6 +1288,10 @@ static int dash_write_packet(AVFormatContext *s,
AVPacket *pkt)
format_date_now(c->availability_start_time,
sizeof(c->availability_start_time));
+ if (!os->chunk_duration && pkt->duration)
+ os->chunk_duration = av_rescale_q(pkt->duration, st->time_base,
+ AV_TIME_BASE_Q);
+
if (c->use_template && !c->use_timeline) {
elapsed_duration = pkt->pts - os->first_pts;
seg_end_duration = (int64_t) os->segment_index * c->seg_duration;
--
1.9.1
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