stream: report chapter times, use time seeks for DVD chapters

Allow the stream layer to report chapter times. Extend stream_dvd to do
this. I'm not 100% sure whether the re-used code is bug-free (because it
was used for slave-mode and/or debugging only).

MAke the frontend do time-based seeks when switching DVD chapters. I'm
not sure if there's a real reason STREAM_CTRL_SEEK_TO_CHAPTER exists
(maybe/hopefully not), but we will see.

Note that querying chapter times in demuxer_chapter_time() with the new
STREAM_CTRL_GET_CHAPTER_TIME could be excessively slow, especially with
the cache enabled. The frontend likes to query chapter times very often.
Additionally, stream_dvd uses some sort of quadratic algorithm to list
times for all chapters. For this reason, we try to query all chapters on
start (after the demuxer is opened), and add the chapters to the demuxer
chapter list. demuxer_chapter_time() will get the time from that list,
instead of asking the stream layer over and over again.

This assumes stream_dvd knows the list of chapters at the start, and
also  that the list of chapters never changes during playback. This
seems to be true, and the only exception, switching DVD titles, is not
supported at runtime (and doesn't need to be supported).

1 files changed, 17 insertions, 0 deletions

diff --git a/demux/demux.c b/demux/demux.c
index 94f54fcbfd..f95a134903 100644
--- a/demux/demux.c
+++ b/demux/demux.c
@@ -101,6 +101,8 @@ const demuxer_desc_t *const demuxer_list[] = {
     NULL
 };
 
+static void add_stream_chapters(struct demuxer *demuxer);
+
 static int packet_destroy(void *ptr)
 {
     struct demux_packet *dp = ptr;
@@ -932,6 +934,7 @@ static struct demuxer *open_given_type(struct MPOpts *opts,
             // Doesn't work, because stream_pts is a "guess".
             demuxer->accurate_seek = false;
         }
+        add_stream_chapters(demuxer);
         demuxer_sort_chapters(demuxer);
         return demuxer;
     } else {
@@ -1300,6 +1303,20 @@ int demuxer_add_chapter(demuxer_t *demuxer, struct bstr name,
     return 0;
 }
 
+static void add_stream_chapters(struct demuxer *demuxer)
+{
+    if (demuxer->num_chapters)
+        return;
+    int num_chapters = demuxer_chapter_count(demuxer);
+    for (int n = 0; n < num_chapters; n++) {
+        double p = n;
+        if (stream_control(demuxer->stream, STREAM_CTRL_GET_CHAPTER_TIME, &p)
+                != STREAM_OK)
+            return;
+        demuxer_add_chapter(demuxer, bstr0(""), p * 1e9, 0);
+    }
+}
+
 /**
  * \brief demuxer_seek_chapter() seeks to a chapter in two possible ways:
  *        either using the demuxer->chapters structure set by the demuxer