Fix T94768: Crash in VSE prefetching

If timeline contains scene strip outside of edited meta strip, this will
cause crash. This is because prefetchin ignored meta strips being edited
when rendering, but did check for scene strips only inside edited meta
strip.

Change active seqbase pointer when entering meta strip. This makes it
possible to prefetch only content that is being presented to user.

2 files changed, 18 insertions, 1 deletions

diff --git a/source/blender/editors/space_sequencer/sequencer_edit.c b/source/blender/editors/space_sequencer/sequencer_edit.c
index e9f37fa6838..c1b483f27e8 100644
--- a/source/blender/editors/space_sequencer/sequencer_edit.c
+++ b/source/blender/editors/space_sequencer/sequencer_edit.c
@@ -1950,6 +1950,8 @@ static int sequencer_meta_toggle_exec(bContext *C, wmOperator *UNUSED(op))
   Editing *ed = SEQ_editing_get(scene);
   Sequence *active_seq = SEQ_select_active_get(scene);
 
+  SEQ_prefetch_stop(scene);
+
   if (active_seq && active_seq->type == SEQ_TYPE_META && active_seq->flag & SELECT) {
     /* Enter meta-strip. */
     SEQ_meta_stack_alloc(ed, active_seq);
diff --git a/source/blender/sequencer/intern/prefetch.c b/source/blender/sequencer/intern/prefetch.c
index 0c45eb09492..42affae26ed 100644
--- a/source/blender/sequencer/intern/prefetch.c
+++ b/source/blender/sequencer/intern/prefetch.c
@@ -328,6 +328,20 @@ static void seq_prefetch_update_scene(Scene *scene)
   seq_prefetch_init_depsgraph(pfjob);
 }
 
+static void seq_prefetch_update_active_seqbase(PrefetchJob *pfjob)
+{
+  MetaStack *ms_orig = SEQ_meta_stack_active_get(SEQ_editing_get(pfjob->scene));
+  Editing *ed_eval = SEQ_editing_get(pfjob->scene_eval);
+
+  if (ms_orig != NULL) {
+    Sequence *meta_eval = seq_prefetch_get_original_sequence(ms_orig->parseq, pfjob->scene_eval);
+    SEQ_seqbase_active_set(ed_eval, &meta_eval->seqbase);
+  }
+  else {
+    SEQ_seqbase_active_set(ed_eval, &ed_eval->seqbase);
+  }
+}
+
 static void seq_prefetch_resume(Scene *scene)
 {
   PrefetchJob *pfjob = seq_prefetch_job_get(scene);
@@ -486,7 +500,7 @@ static void *seq_prefetch_frames(void *job)
      */
     pfjob->scene_eval->ed->prefetch_job = pfjob;
 
-    ListBase *seqbase = SEQ_active_seqbase_get(SEQ_editing_get(pfjob->scene));
+    ListBase *seqbase = SEQ_active_seqbase_get(SEQ_editing_get(pfjob->scene_eval));
     if (seq_prefetch_must_skip_frame(pfjob, seqbase)) {
       pfjob->num_frames_prefetched++;
       continue;
@@ -549,6 +563,7 @@ static PrefetchJob *seq_prefetch_start_ex(const SeqRenderData *context, float cf
 
   seq_prefetch_update_scene(context->scene);
   seq_prefetch_update_context(context);
+  seq_prefetch_update_active_seqbase(pfjob);
 
   BLI_threadpool_remove(&pfjob->threads, pfjob);
   BLI_threadpool_insert(&pfjob->threads, pfjob);