scan: fix rescan avoidance logic

We need to rescan when the number of previews changes.

4 files changed, 23 insertions, 6 deletions

diff --git a/libhb/common.h b/libhb/common.h
index b540de9de..4f39c8944 100644
--- a/libhb/common.h
+++ b/libhb/common.h
@@ -962,6 +962,7 @@ struct hb_title_s
     /* Exact duration (in 1/90000s) */
     uint64_t      duration;
 
+    int           preview_count;
     int           has_resolution_change;
     hb_geometry_t geometry;
     hb_rational_t dar;             // aspect ratio for the title's video
diff --git a/libhb/hb.c b/libhb/hb.c
index 2f4a71720..55800c832 100644
--- a/libhb/hb.c
+++ b/libhb/hb.c
@@ -610,14 +610,29 @@ void hb_scan( hb_handle_t * h, const char * path, int title_index,
             title = hb_list_item(h->title_set.list_title, ii);
             if (title->index == title_index)
             {
-                // Title has already been scanned.
-                hb_lock( h->state_lock );
-                h->state.state = HB_STATE_SCANDONE;
-                hb_unlock( h->state_lock );
-                return;
+                // In some cases, we don't care what the preview count is.
+                // E.g. when rescanning at the start of a job. In these
+                // cases, the caller can set preview_count to -1 to tell
+                // us to use the same count as the previous scan, if known.
+                if (preview_count < 0)
+                {
+                    preview_count = title->preview_count;
+                }
+                if (preview_count == title->preview_count)
+                {
+                    // Title has already been scanned.
+                    hb_lock( h->state_lock );
+                    h->state.state = HB_STATE_SCANDONE;
+                    hb_unlock( h->state_lock );
+                    return;
+                }
             }
         }
     }
+    if (preview_count < 0)
+    {
+        preview_count = 10;
+    }
 
     h->scan_die = 0;
 
diff --git a/libhb/hb_json.c b/libhb/hb_json.c
index a9d104b90..e5c64bb9f 100644
--- a/libhb/hb_json.c
+++ b/libhb/hb_json.c
@@ -751,7 +751,7 @@ void hb_json_job_scan( hb_handle_t * h, const char * json_job )
     // If the job wants to use Hardware decode, it must also be
     // enabled during scan.  So enable it here.
     hb_hwd_set_enable(h, use_hwd);
-    hb_scan(h, path, title_index, 10, 0, 0);
+    hb_scan(h, path, title_index, -1, 0, 0);
 
     // Wait for scan to complete
     hb_state_t state;
diff --git a/libhb/scan.c b/libhb/scan.c
index 2280644ba..8626ccca8 100644
--- a/libhb/scan.c
+++ b/libhb/scan.c
@@ -240,6 +240,7 @@ static void ScanFunc( void * _data )
             hb_title_close( &title );
             continue;
         }
+        title->preview_count = npreviews;
 
         /* Make sure we found audio rates and bitrates */
         for( j = 0; j < hb_list_count( title->list_audio ); )