iter9 Phase 6 α-7: monotonic per-context timestamp counter

Replace gettimeofday in RequestEndPicture with object_context-scoped
counter producing small us values (1, 2, 3, ...) so OUTPUT QBUF
timestamp and DPB.reference_ts match ffmpeg-v4l2request's pattern.

Phase 5 IMP-1: counter scoped to object_context (not driver_data) to
avoid multi-context collisions.

Empirical confirmation only — reviewer's CRIT-1 predicts this is
inert (VP9/MPEG-2 use same path and PASS). If α-7 produces the same
broken hash, the libva wire-byte search space is exhausted and iter10
must pivot to slice-data inspection or kernel investigation.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/context.c

@@ -254,6 +254,7 @@ VAStatus RequestCreateContext(VADriverContextP context, VAConfigID config_id,
 		goto error;
 	}
 	memset(&context_object->dpb, 0, sizeof(context_object->dpb));
+	context_object->timestamp_counter = 0;	/* iter9 α-7 */
 
 	/*
 	 * Initialize the OUTPUT (bitstream-input) buffer pool. Sized by

src/context.h

@@ -55,6 +55,15 @@ struct object_context {
 	struct h264_dpb dpb;
 	bool h264_start_code;
 
+	/*
+	 * iter9 α-7: monotonic per-context timestamp counter (us). Replaces
+	 * gettimeofday in EndPicture so DPB.reference_ts / OUTPUT QBUF ts
+	 * are small values matching ffmpeg-v4l2request's pattern. Placed
+	 * here (object_context) not driver_data per Phase 5 IMP-1 to avoid
+	 * cross-context collisions.
+	 */
+	uint64_t timestamp_counter;
+
 	/* fresnel-fourier iter4: VP9 loop-filter delta state, persisted across
 	 * frames per kernel UAPI <linux/v4l2-controls.h>:2578 ("If this syntax
 	 * element is not present in the bitstream, users should pass its last

src/picture.c

@@ -461,7 +461,19 @@ VAStatus RequestEndPicture(VADriverContextP context, VAContextID context_id)
 	if (surface_object == NULL)
 		return VA_STATUS_ERROR_INVALID_SURFACE;
 
-	gettimeofday(&surface_object->timestamp, NULL);
+	/*
+	 * iter9 α-7: monotonic per-context counter instead of gettimeofday,
+	 * so DPB.reference_ts / OUTPUT QBUF ts stay small (matches
+	 * ffmpeg-v4l2request's pattern). gettimeofday's giant ns may or may
+	 * not be load-bearing for rkvdec's reference resolution — Phase 5
+	 * reviewer flagged this as low-probability (VP9/MPEG-2 use the same
+	 * pattern and PASS), but this is the only remaining wire-byte diff.
+	 */
+	context_object->timestamp_counter++;
+	surface_object->timestamp.tv_sec =
+		(time_t)(context_object->timestamp_counter / 1000000);
+	surface_object->timestamp.tv_usec =
+		(suseconds_t)(context_object->timestamp_counter % 1000000);
 
 	/*
 	 * iter6: request_fd was bound to the surface in BeginPicture from