avfilter/af_stereowiden: add timeline support

libavfilter/af_stereowiden.c

@@ -113,8 +113,13 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
         if (s->cur == s->buffer + s->length)
             s->cur = s->buffer;
 
-        dst[0] = drymix * left - crossfeed * right - feedback * s->cur[1];
+        if (ctx->is_disabled) {
-        dst[1] = drymix * right - crossfeed * left - feedback * s->cur[0];
+            dst[0] = left;
+            dst[1] = right;
+        } else {
+            dst[0] = drymix * left - crossfeed * right - feedback * s->cur[1];
+            dst[1] = drymix * right - crossfeed * left - feedback * s->cur[0];
+        }
 
         s->cur[0] = left;
         s->cur[1] = right;
@@ -159,4 +164,5 @@ AVFilter ff_af_stereowiden = {
     .uninit         = uninit,
     .inputs         = inputs,
     .outputs        = outputs,
+    .flags          = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
 };