[libdvdnav-devel] [Git][videolan/libdvdnav][master] Handle out-of-order ADMAP entries by looking ahead from any

[Jean-Baptiste Kempf]

Jean-Baptiste Kempf pushed to branch master at VideoLAN / libdvdnav


Commits:
f2b095c7 by John Sullivan at 2019-11-11T20:57:14Z
Handle out-of-order ADMAP entries by looking ahead from any
prospective match and skipping entries if we see the sequence go back
down again.

- - - - -


1 changed file:

- src/searching.c


Changes:

=====================================
src/searching.c
=====================================
@@ -84,8 +84,33 @@ static dvdnav_status_t dvdnav_scan_admap(dvdnav_t *this, int32_t domain, uint32_
 
       /* fprintf(MSG_OUT, "libdvdnav: Found block %u\n", next_vobu); */
 
-      if(vobu_start <= seekto_block && next_vobu > seekto_block)
-        break;
+      if(vobu_start <= seekto_block && next_vobu > seekto_block) {
+        /* We expect the ADMAP to be sorted in order of increasing
+         * sector number, but some discs store out-of-order values in
+         * cells that would not normally be playable, cells which
+         * themselves contain bad sectors. The straightforward linear
+         * search would get "stuck" on those values, essentially
+         * forcing playback of the bad sectors on any sector seek
+         * anywhere within the title. To prevent this, scan the next
+         * few entries to make sure they're all really later than the
+         * current entry, and skip over the out-of-order entries if
+         * not. */
+        uint32_t ooo_address = 0;
+        uint32_t ooo_vobu = SRI_END_OF_CELL;
+        for ( uint32_t check=1 ; check<=32 && address+check<admap_entries ; check++ ) {
+          uint32_t check_vobu = admap->vobu_start_sectors[address+check];
+          if (check_vobu < next_vobu && check_vobu < ooo_vobu) {
+            ooo_address = address+check;
+            ooo_vobu = check_vobu;
+          }
+        }
+        if (ooo_vobu < next_vobu) {
+          address = ooo_address;
+          next_vobu = ooo_vobu;
+        } else {
+          break;
+        }
+      }
       vobu_start = next_vobu;
       address++;
     }



View it on GitLab: https://code.videolan.org/videolan/libdvdnav/commit/f2b095c75d2b358d2a76d970d0512f79cfa19295

-- 
View it on GitLab: https://code.videolan.org/videolan/libdvdnav/commit/f2b095c75d2b358d2a76d970d0512f79cfa19295
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