edl: make it possible to delay-load files with multiple tracks

Until now, delay-loading was for files with single tracks only
(basically what DASH and HLS like to expose, so adaptive streaming and
codec selection becomes easier - for sites, not for us). But they also
provide some interleaved versions, probably for compatibility. Until
now, we were forced to eagerly load it (making startup slightly slower).

But there is not much missing. We just need a way to provide multiple
metadata entries, and use them to represent each track.

A side effect is now that the "track_meta" header can be used for normal
EDL files too.

3 files changed, 49 insertions, 17 deletions

diff --git a/demux/demux_edl.c b/demux/demux_edl.c
index e71c1dfd99..f72aeb2c03 100644
--- a/demux/demux_edl.c
+++ b/demux/demux_edl.c
@@ -50,7 +50,8 @@ struct tl_parts {
     bool disable_chapters;
     bool dash, no_clip, delay_open;
     char *init_fragment_url;
-    struct sh_stream *sh_meta;
+    struct sh_stream **sh_meta;
+    int num_sh_meta;
     struct tl_part *parts;
     int num_parts;
     struct tl_parts *next;
@@ -145,12 +146,22 @@ static bool get_param_time(struct parse_ctx *ctx, const char *name, double *t)
 static struct tl_parts *add_part(struct tl_root *root)
 {
     struct tl_parts *tl = talloc_zero(root, struct tl_parts);
-    tl->sh_meta = demux_alloc_sh_stream(STREAM_TYPE_COUNT);
-    talloc_steal(tl, tl->sh_meta);
     MP_TARRAY_APPEND(root, root->pars, root->num_pars, tl);
     return tl;
 }
 
+static struct sh_stream *get_meta(struct tl_parts *tl, int index)
+{
+    for (int n = 0; n < tl->num_sh_meta; n++) {
+        if (tl->sh_meta[n]->index == index)
+            return tl->sh_meta[n];
+    }
+    struct sh_stream *sh = demux_alloc_sh_stream(STREAM_TYPE_COUNT);
+    talloc_steal(tl, sh);
+    MP_TARRAY_APPEND(tl, tl->sh_meta, tl->num_sh_meta, sh);
+    return sh;
+}
+
 /* Returns a list of parts, or NULL on parse error.
  * Syntax (without file header or URI prefix):
  *    url      ::= <entry> ( (';' | '\n') <entry> )*
@@ -223,12 +234,15 @@ static struct tl_root *parse_edl(bstr str, struct mp_log *log)
             } else if (bstr_equals0(f_type, "no_chapters")) {
                 tl->disable_chapters = true;
             } else if (bstr_equals0(f_type, "track_meta")) {
-                struct sh_stream *sh = tl->sh_meta;
+                int index = get_param_int(&ctx, "index", -1);
+                struct sh_stream *sh = index < 0 && tl->num_sh_meta
+                    ? tl->sh_meta[tl->num_sh_meta - 1]
+                    : get_meta(tl, index);
                 sh->lang = get_param0(&ctx, sh, "lang");
                 sh->title = get_param0(&ctx, sh, "title");
                 sh->hls_bitrate = get_param_int(&ctx, "byterate", 0) * 8;
             } else if (bstr_equals0(f_type, "delay_open")) {
-                struct sh_stream *sh = tl->sh_meta;
+                struct sh_stream *sh = get_meta(tl, tl->num_sh_meta);
                 bstr mt = get_param(&ctx, "media_type");
                 if (bstr_equals0(mt, "video")) {
                     sh->type = sh->codec->type = STREAM_VIDEO;
@@ -371,8 +385,12 @@ static struct timeline_par *build_timeline(struct timeline *root,
     tl->delay_open = parts->delay_open;
 
     // There is no copy function for sh_stream, so just steal it.
-    tl->sh_meta = talloc_steal(tl, parts->sh_meta);
-    parts->sh_meta = NULL;
+    for (int n = 0; n < parts->num_sh_meta; n++) {
+        MP_TARRAY_APPEND(tl, tl->sh_meta, tl->num_sh_meta,
+                         talloc_steal(tl, parts->sh_meta[n]));
+        parts->sh_meta[n] = NULL;
+    }
+    parts->num_sh_meta = 0;
 
     if (parts->init_fragment_url && parts->init_fragment_url[0]) {
         MP_VERBOSE(root, "Opening init fragment...\n");
diff --git a/demux/demux_timeline.c b/demux/demux_timeline.c
index ab6d29b538..eb923d92e4 100644
--- a/demux/demux_timeline.c
+++ b/demux/demux_timeline.c
@@ -528,6 +528,17 @@ static void apply_meta(struct sh_stream *dst, struct sh_stream *src)
         dst->attached_picture = src->attached_picture;
 }
 
+// This is mostly for EDL user-defined metadata.
+static struct sh_stream *find_matching_meta(struct timeline_par *tl, int index)
+{
+    for (int n = 0; n < tl->num_sh_meta; n++) {
+        struct sh_stream *sh = tl->sh_meta[n];
+        if (sh->index == index || sh->index < 0)
+            return sh;
+    }
+    return NULL;
+}
+
 static bool add_tl(struct demuxer *demuxer, struct timeline_par *tl)
 {
     struct priv *p = demuxer->priv;
@@ -553,7 +564,7 @@ static bool add_tl(struct demuxer *demuxer, struct timeline_par *tl)
     // delay_open streams normally have meta==NULL, and 1 virtual stream
     int num_streams = 0;
     if (tl->delay_open) {
-        num_streams = 1;
+        num_streams = tl->num_sh_meta;
     } else if (meta) {
         num_streams = demux_get_num_stream(meta);
     }
@@ -561,9 +572,10 @@ static bool add_tl(struct demuxer *demuxer, struct timeline_par *tl)
         struct sh_stream *new = NULL;
 
         if (tl->delay_open) {
-            assert(tl->sh_meta);
-            new = demux_alloc_sh_stream(tl->sh_meta->type);
-            new->codec = tl->sh_meta->codec;
+            struct sh_stream *tsh = tl->sh_meta[n];
+            new = demux_alloc_sh_stream(tsh->type);
+            new->codec = tsh->codec;
+            apply_meta(new, tsh);
             demuxer->is_network = true;
             demuxer->is_streaming = true;
         } else {
@@ -571,11 +583,11 @@ static bool add_tl(struct demuxer *demuxer, struct timeline_par *tl)
             new = demux_alloc_sh_stream(sh->type);
             apply_meta(new, sh);
             new->codec = sh->codec;
+            struct sh_stream *tsh = find_matching_meta(tl, n);
+            if (tsh)
+                apply_meta(new, tsh);
         }
 
-        if (tl->sh_meta)
-            apply_meta(new, tl->sh_meta);
-
         demux_add_sh_stream(demuxer, new);
         struct virtual_stream *vs = talloc_ptrtype(p, vs);
         *vs = (struct virtual_stream){
diff --git a/demux/timeline.h b/demux/timeline.h
index faeec53b32..93919a5c51 100644
--- a/demux/timeline.h
+++ b/demux/timeline.h
@@ -24,9 +24,11 @@ struct timeline_par {
     bstr init_fragment;
     bool dash, no_clip, delay_open;
 
-    // If non-NULL, _some_ fields are used. If delay_open==true, this must be
-    // set, and the codec info is used.
-    struct sh_stream *sh_meta;
+    // Of any of these, _some_ fields are used. If delay_open==true, this
+    // describes each sub-track, and the codec info is used.
+    // In both cases, the metadata is mapped to actual tracks in specific ways.
+    struct sh_stream **sh_meta;
+    int num_sh_meta;
 
     // Segments to play, ordered by time.
     struct timeline_part *parts;