avfilter/af_afade: make sure that in is available

libavfilter/af_afade.c

@@ -459,17 +459,18 @@ static int activate(AVFilterContext *ctx)
         } else if (ff_inlink_acknowledge_status(ctx->inputs[1], &status, &pts)) {
             ff_outlink_set_status(ctx->outputs[0], status, pts);
             return 0;
-        } else {
-            if (ff_outlink_frame_wanted(ctx->outputs[0]) && !in) {
+        } else if (!ret) {
+            if (ff_outlink_frame_wanted(ctx->outputs[0])) {
                 ff_inlink_request_frame(ctx->inputs[1]);
                 return 0;
             }
-        }
+        } else {
             in->pts = s->pts;
             s->pts += av_rescale_q(in->nb_samples,
                       (AVRational){ 1, outlink->sample_rate }, outlink->time_base);
             return ff_filter_frame(outlink, in);
         }
+    }
 
     if (ff_inlink_queued_samples(ctx->inputs[0]) > s->nb_samples) {
         nb_samples = ff_inlink_queued_samples(ctx->inputs[0]) - s->nb_samples;