diff --git a/src/picture.c b/src/picture.c
index c126a64..3f010e5 100644
--- a/src/picture.c
+++ b/src/picture.c
@@ -321,6 +321,29 @@ VAStatus RequestBeginPicture(VADriverContextP context, VAContextID context_id,
 		if (cap_slot == NULL)
 			return VA_STATUS_ERROR_ALLOCATION_FAILED;
 		surface_bind_slot(surface_object, cap_slot);
+
+		/*
+		 * iter8 Phase 7 IMP-1 experiment: env-gated CAPTURE buffer
+		 * pre-zero. LIBVA_V4L2_ZERO_CAPTURE=1 wipes the slot's mmap'd
+		 * region before kernel decode. Discriminates "kernel writes
+		 * partial then aborts" from "kernel writes nothing and we
+		 * see stale residue."
+		 */
+		{
+			static const char *zero_env = NULL;
+			static bool zero_env_checked = false;
+			if (!zero_env_checked) {
+				zero_env = getenv("LIBVA_V4L2_ZERO_CAPTURE");
+				zero_env_checked = true;
+			}
+			if (zero_env != NULL && zero_env[0] == '1') {
+				unsigned int b;
+				for (b = 0; b < cap_slot->buffers_count; b++)
+					if (cap_slot->map[b] != NULL)
+						memset(cap_slot->map[b], 0,
+						       cap_slot->map_lengths[b]);
+			}
+		}
 	}
 
 	/*