Apple doesn't have an official spec for LHLS. Meanwhile hls.js player folks are
trying to standardize a open LHLS spec. The draft spec is available in
https://github.com/video-dev/hlsjs-rfcs/blob/lhls-spec/proposals/0001-lhls.md
This option will also try to comply with the above open spec, till Apple's spec
officially supports it.
Applicable only when @var{streaming} and @var{hls_playlist} options are enabled.
---
doc/muxers.texi | 7 +++++++
libavformat/dashenc.c | 31 +++++++++++++++++++++++++++----
2 files changed, 34 insertions(+), 4 deletions(-)
diff --git a/doc/muxers.texi b/doc/muxers.texi
index 809f88662e..f09a89db82 100644
--- a/doc/muxers.texi
+++ b/doc/muxers.texi
@@ -305,6 +305,13 @@ If this flag is set, the dash segment files will be in in
WebM format.
@item -ignore_io_errors @var{ignore_io_errors}
Ignore IO errors during open and write. Useful for long-duration runs with
network output.
+@item -lhls @var{lhls}
+Enable Low-latency HLS(LHLS). Adds #EXT-X-PREFETCH tag with current segment's
URI.
+Apple doesn't have an official spec for LHLS. Meanwhile hls.js player folks are
+trying to standardize a open LHLS spec. The draft spec is available in
https://github.com/video-dev/hlsjs-rfcs/blob/lhls-spec/proposals/0001-lhls.md
+This option will also try to comply with the above open spec, till Apple's
spec officially supports it.
+Applicable only when @var{streaming} and @var{hls_playlist} options are
enabled.
+
@end table
@anchor{framecrc}
diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
index f797b7bd1c..8685642437 100644
--- a/libavformat/dashenc.c
+++ b/libavformat/dashenc.c
@@ -139,6 +139,7 @@ typedef struct DASHContext {
char *format_options_str;
SegmentType segment_type_option; /* segment type as specified in options
*/
int ignore_io_errors;
+ int lhls;
} DASHContext;
static struct codec_string {
@@ -418,7 +419,8 @@ static void get_start_index_number(OutputStream *os,
DASHContext *c,
}
static void write_hls_media_playlist(OutputStream *os, AVFormatContext *s,
- int representation_id, int final) {
+ int representation_id, int final,
+ char *prefetch_url) {
DASHContext *c = s->priv_data;
int timescale = os->ctx->streams[0]->time_base.den;
char temp_filename_hls[1024];
@@ -431,6 +433,11 @@ static void write_hls_media_playlist(OutputStream *os,
AVFormatContext *s,
int i, start_index, start_number;
get_start_index_number(os, c, &start_index, &start_number);
+
+ if (!c->hls_playlist || start_index >= os->nb_segments ||
+ os->segment_type != SEGMENT_TYPE_MP4)
+ return;
+
get_hls_playlist_name(filename_hls, sizeof(filename_hls),
c->dirname, representation_id);
@@ -468,6 +475,9 @@ static void write_hls_media_playlist(OutputStream *os,
AVFormatContext *s,
}
}
+ if (prefetch_url)
+ avio_printf(c->m3u8_out, "#EXT-X-PREFETCH:%s\n", prefetch_url);
+
if (final)
ff_hls_write_end_list(c->m3u8_out);
@@ -594,9 +604,8 @@ static void output_segment_list(OutputStream *os,
AVIOContext *out, AVFormatCont
}
avio_printf(out, "\t\t\t\t</SegmentList>\n");
}
- if (c->hls_playlist && start_index < os->nb_segments && os->segment_type
== SEGMENT_TYPE_MP4)
- {
- write_hls_media_playlist(os, s, representation_id, final);
+ if (!c->lhls || final) {
+ write_hls_media_playlist(os, s, representation_id, final, NULL);
}
}
@@ -1054,6 +1063,15 @@ static int dash_init(AVFormatContext *s)
c->seg_duration = c->min_seg_duration;
}
#endif
+ if (c->lhls && !c->streaming) {
+ av_log(s, AV_LOG_WARNING, "LHLS option will be ignored as streaming is
not enabled\n");
+ c->lhls = 0;
+ }
+
+ if (c->lhls && !c->hls_playlist) {
+ av_log(s, AV_LOG_WARNING, "LHLS option will be ignored as hls_playlist
is not enabled\n");
+ c->lhls = 0;
+ }
av_strlcpy(c->dirname, s->url, sizeof(c->dirname));
ptr = strrchr(c->dirname, '/');
@@ -1635,6 +1653,10 @@ static int dash_write_packet(AVFormatContext *s,
AVPacket *pkt)
if (ret < 0) {
return handle_io_open_error(s, ret, os->temp_path);
}
+ if (c->lhls) {
+ char *prefetch_url = use_rename ? NULL : os->filename;
+ write_hls_media_playlist(os, s, pkt->stream_index, 0,
prefetch_url);
+ }
}
//write out the data immediately in streaming mode
@@ -1760,6 +1782,7 @@ static const AVOption options[] = {
{ "mp4", "make segment file in ISOBMFF format", 0, AV_OPT_TYPE_CONST,
{.i64 = SEGMENT_TYPE_MP4 }, 0, UINT_MAX, E, "segment_type"},
{ "webm", "make segment file in WebM format", 0, AV_OPT_TYPE_CONST, {.i64
= SEGMENT_TYPE_WEBM }, 0, UINT_MAX, E, "segment_type"},
{ "ignore_io_errors", "Ignore IO errors during open and write. Useful for
long-duration runs with network output", OFFSET(ignore_io_errors),
AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, E },
+ { "lhls", "Enable Low-latency HLS(LHLS). Adds #EXT-X-PREFETCH tag with
current segment's URI", OFFSET(lhls), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, E },
{ NULL },
};
--
2.17.1 (Apple Git-112)
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