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avformat/dashenc: add an option to write a Latency element 

Allows to set an intended target latency while streaming that clients can use
to measure when using low latency mode.

Signed-off-by: James Almer <jamrial@gmail.com>
This commit is contained in:
James Almer 2019-12-12 22:13:13 -03:00
parent bc4f0e713b
commit 05b3460991
1 changed files with 26 additions and 1 deletions
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27
libavformat/dashenc.c
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@ -189,6 +189,8 @@ typedef struct DASHContext {
int write_prft;
int64_t max_gop_size;
int profile;
int64_t target_latency;
int target_latency_refid;
} DASHContext;
static struct codec_string {
@ -1150,6 +1152,14 @@ static int write_manifest(AVFormatContext *s, int final)
av_free(escaped);
}
avio_printf(out, "\t</ProgramInformation>\n");
if (!final && c->target_latency && c->target_latency_refid >= 0) {
avio_printf(out, "\t<ServiceDescription id=\"0\">\n");
avio_printf(out, "\t\t<Latency target=\"%"PRId64"\"", c->target_latency / 1000);
if (s->nb_streams > 1)
avio_printf(out, " referenceId=\"%d\"", c->target_latency_refid);
avio_printf(out, "/>\n");
avio_printf(out, "\t</ServiceDescription>\n");
}
if (c->window_size && s->nb_streams > 0 && c->streams[0].nb_segments > 0 && !c->use_template) {
OutputStream *os = &c->streams[0];
@ -1318,6 +1328,11 @@ static int dash_init(AVFormatContext *s)
c->ldash = 0;
}
if (c->target_latency && !c->streaming) {
av_log(s, AV_LOG_WARNING, "Target latency option will be ignored as streaming is not enabled\n");
c->target_latency = 0;
}
if (c->global_sidx && !c->single_file) {
av_log(s, AV_LOG_WARNING, "Global SIDX option will be ignored as single_file is not enabled\n");
c->global_sidx = 0;
@ -1342,6 +1357,11 @@ static int dash_init(AVFormatContext *s)
c->write_prft = 0;
}
if (c->target_latency && !c->write_prft) {
av_log(s, AV_LOG_WARNING, "Target latency option will be ignored as Producer Reference Time element will not be written\n");
c->target_latency = 0;
}
av_strlcpy(c->dirname, s->url, sizeof(c->dirname));
ptr = strrchr(c->dirname, '/');
if (ptr) {
@ -1600,6 +1620,7 @@ static int dash_init(AVFormatContext *s)
av_log(s, AV_LOG_WARNING, "no video stream and P-frame fragmentation set\n");
c->nr_of_streams_flushed = 0;
c->target_latency_refid = -1;
return 0;
}
@ -1966,8 +1987,11 @@ static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
int side_data_size;
AVProducerReferenceTime *prft = (AVProducerReferenceTime *)av_packet_get_side_data(pkt, AV_PKT_DATA_PRFT,
&side_data_size);
if (prft && side_data_size == sizeof(AVProducerReferenceTime) && !prft->flags)
if (prft && side_data_size == sizeof(AVProducerReferenceTime) && !prft->flags) {
os->producer_reference_time = prft->wallclock;
if (c->target_latency_refid < 0)
c->target_latency_refid = pkt->stream_index;
}
os->first_pts = pkt->pts;
}
os->last_pts = pkt->pts;
@ -2252,6 +2276,7 @@ static const AVOption options[] = {
{ "dash", "MPEG-DASH ISO Base media file format live profile", 0, AV_OPT_TYPE_CONST, {.i64 = MPD_PROFILE_DASH }, 0, UINT_MAX, E, "mpd_profile"},
{ "dvb_dash", "DVB-DASH profile", 0, AV_OPT_TYPE_CONST, {.i64 = MPD_PROFILE_DVB }, 0, UINT_MAX, E, "mpd_profile"},
{ "http_opts", "HTTP protocol options", OFFSET(http_opts), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, E },
{ "target_latency", "Set desired target latency for Low-latency dash", OFFSET(target_latency), AV_OPT_TYPE_DURATION, { .i64 = 0 }, 0, INT_MAX, E },
{ NULL },
};