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avformat/dashenc: Added support for Low-latency HLS(Experimental)

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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.
This commit is contained in:
kjeyapal@akamai.com 2018-12-12 21:50:19 +05:30 committed by Karthick J
parent d209a3d50f
commit f22fcd4483
2 changed files with 41 additions and 4 deletions
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8
doc/muxers.texi
View File

@ -305,6 +305,14 @@ 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.
This is an experimental feature.
@end table
@anchor{framecrc}

37
libavformat/dashenc.c
View File

@ -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 +1063,21 @@ static int dash_init(AVFormatContext *s)
c->seg_duration = c->min_seg_duration;
}
#endif
if (c->lhls && s->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL) {
av_log(s, AV_LOG_ERROR,
"LHLS is experimental, Please set -strict experimental in order to enable it.\n");
return AVERROR_EXPERIMENTAL;
}
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 +1659,10 @@ 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 +1788,7 @@ 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(Experimental). Adds #EXT-X-PREFETCH tag with current segment's URI", OFFSET(lhls), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, E },
{ NULL },
};