Fix chapter handling with first chapter not at beginning of file

Before "-chapter 1" did nothing even if the first chapter didn't start
at the beginning of file. Fix it.
Before all chapter property commands (including chapter seek keys)
failed if the current playback position was before the start of the
first chapter. Now they'll work. Relative chapter seeks will go to the
first chapter (even if that's in the wrong direction for backward
seeks).

3 files changed, 5 insertions, 4 deletions

diff --git a/command.c b/command.c
index 4e1a6c87ab..9084ff37df 100644
--- a/command.c
+++ b/command.c
@@ -396,7 +396,7 @@ static int mp_property_chapter(m_option_t *prop, int action, void *arg,
 
     if (mpctx->demuxer)
         chapter = get_current_chapter(mpctx);
-    if (chapter < 0)
+    if (chapter < -1)
         return M_PROPERTY_UNAVAILABLE;
 
     switch (action) {
diff --git a/libmpdemux/demuxer.c b/libmpdemux/demuxer.c
index 0f026dffd6..551fd330c4 100644
--- a/libmpdemux/demuxer.c
+++ b/libmpdemux/demuxer.c
@@ -1529,11 +1529,11 @@ int demuxer_seek_chapter(demuxer_t *demuxer, int chapter, double *seek_pts,
 
 int demuxer_get_current_chapter(demuxer_t *demuxer)
 {
-    int chapter = -1;
+    int chapter = -2;
     if (!demuxer->num_chapters || !demuxer->chapters) {
         if (stream_control(demuxer->stream, STREAM_CTRL_GET_CURRENT_CHAPTER,
                            &chapter) == STREAM_UNSUPPORTED)
-            chapter = -1;
+            chapter = -2;
     } else {
         sh_video_t *sh_video = demuxer->video->sh;
         sh_audio_t *sh_audio = demuxer->audio->sh;
diff --git a/mplayer.c b/mplayer.c
index f5544b8e57..4eec335b99 100644
--- a/mplayer.c
+++ b/mplayer.c
@@ -2790,6 +2790,7 @@ static int seek(MPContext *mpctx, double amount, int style)
     return 0;
 }
 
+// -2 is no chapters, -1 is before first chapter
 int get_current_chapter(struct MPContext *mpctx)
 {
     if (!mpctx->chapters || !mpctx->sh_video)
@@ -4058,7 +4059,7 @@ if (seek_to_sec || mpctx->timeline) {
     seek(mpctx, seek_to_sec, SEEK_ABSOLUTE);
     end_at.pos += seek_to_sec;
 }
-if (opts->chapterrange[0] > 1) {
+if (opts->chapterrange[0] > 0) {
     double pts;
     if (seek_chapter(mpctx, opts->chapterrange[0]-1, &pts, NULL) >= 0
         && pts > -1.0)