skip_to_segment

libavformat/dashenc.c

@@ -100,6 +100,7 @@ typedef struct DASHContext {
     AVRational min_frame_rate, max_frame_rate;
     int ambiguous_frame_rate;
     const char *utc_timing_url;
+    int skip_to_segment;
 } DASHContext;
 
 static struct codec_string {
@@ -780,7 +781,10 @@ static int dash_init(AVFormatContext *s)
         os->init_start_pos = 0;
 
         if (!strcmp(os->format_name, "mp4")) {
-            av_dict_set(&opts, "movflags", "frag_custom+dash+delay_moov", 0);
+            if (c->skip_to_segment > 1)
+                av_dict_set(&opts, "movflags", "frag_custom+dash+delay_moov+frag_discont", 0);
+            else
+                av_dict_set(&opts, "movflags", "frag_custom+dash+delay_moov", 0);
         } else {
             dict_set_int(&opts, "cluster_time_limit", c->min_seg_duration / 1000, 0);
             dict_set_int(&opts, "cluster_size_limit", 5 * 1024 * 1024, 0); // set a large cluster size limit
@@ -793,6 +797,9 @@ static int dash_init(AVFormatContext *s)
 
         av_log(s, AV_LOG_VERBOSE, "Representation %d init segment will be written to: %s\n", i, filename);
 
+        if (c->skip_to_segment > 1)
+            av_opt_set_int(os->ctx, "fragments", c->skip_to_segment, AV_OPT_SEARCH_CHILDREN);
+
         // Flush init segment
         // except for mp4, since delay_moov is set and the init segment
         // is then flushed after the first packets
@@ -822,7 +829,7 @@ static int dash_init(AVFormatContext *s)
         os->first_pts = AV_NOPTS_VALUE;
         os->max_pts = AV_NOPTS_VALUE;
         os->last_dts = AV_NOPTS_VALUE;
-        os->segment_index = 1;
+        os->segment_index = c->skip_to_segment;
     }
 
     if (!c->has_video && c->min_seg_duration <= 0) {
@@ -1050,6 +1057,12 @@ static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
     DASHContext *c = s->priv_data;
     AVStream *st = s->streams[pkt->stream_index];
     OutputStream *os = &c->streams[pkt->stream_index];
+    int64_t seg_end_duration = (os->segment_index - c->skip_to_segment + 1) * (int64_t) c->min_seg_duration;
+
+    /* av_log(s, AV_LOG_WARNING, "segment_index=%d\n", os->segment_index); */
+    /* av_log(s, AV_LOG_WARNING, "min_seg_duration=%d\n", c->min_seg_duration); */
+    /* av_log(s, AV_LOG_WARNING, "seg_end_duration=%d\n", seg_end_duration); */
+
     int ret;
 
     ret = update_stream_extradata(s, os, st->codecpar);
@@ -1080,7 +1093,7 @@ static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
     if ((!c->has_video || st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) &&
         pkt->flags & AV_PKT_FLAG_KEY && os->packets_written &&
         av_compare_ts(pkt->pts - os->start_pts, st->time_base,
-                      c->min_seg_duration, AV_TIME_BASE_Q) >= 0) {
+                      seg_end_duration, AV_TIME_BASE_Q) >= 0) {
         int64_t prev_duration = c->last_duration;
 
         c->last_duration = av_rescale_q(pkt->pts - os->start_pts,
@@ -1190,6 +1203,7 @@ static const AVOption options[] = {
     { "init_seg_name", "DASH-templated name to used for the initialization segment", OFFSET(init_seg_name), AV_OPT_TYPE_STRING, {.str = "init-stream$RepresentationID$.m4s"}, 0, 0, E },
     { "media_seg_name", "DASH-templated name to used for the media segments", OFFSET(media_seg_name), AV_OPT_TYPE_STRING, {.str = "chunk-stream$RepresentationID$-$Number%05d$.m4s"}, 0, 0, E },
     { "utc_timing_url", "URL of the page that will return the UTC timestamp in ISO format", OFFSET(utc_timing_url), AV_OPT_TYPE_STRING, { 0 }, 0, 0, E },
+    { "skip_to_segment", "first segment number to actually write", OFFSET(skip_to_segment), AV_OPT_TYPE_INT, { .i64 = 1 }, 1, INT_MAX, E },
     { NULL },
 };