linux-kernel - [PATCH v2 10/23] media: h264: Sort p/b reflist using frame

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Message-Id: <20220331193726.289559-11-nicolas.dufresne@collabora.com>
Date:   Thu, 31 Mar 2022 15:37:12 -0400
From:   Nicolas Dufresne <nicolas.dufresne@...labora.com>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     kernel@...labora.com,
        Sebastian Fricke <sebastian.fricke@...labora.com>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 10/23] media: h264: Sort p/b reflist using frame_num

In the reference list builder, frame_num refers to FrameNumWrap
in the spec, which is the same as the pic_num for frame decoding.
The same applies for long_term_pic_num and long_term_frame_idx.

Sort all type of references by frame_num so the sort can be reused
for fields reflist were the sorting is done using frame_num instead.
In short, pic_num is never actually used for building reference
lists.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@...labora.com>
---
 drivers/media/v4l2-core/v4l2-h264.c | 23 +++++++++++++----------
 include/media/v4l2-h264.h           |  2 --
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-h264.c b/drivers/media/v4l2-core/v4l2-h264.c
index bcf9b7774560..7e1eba03099a 100644
--- a/drivers/media/v4l2-core/v4l2-h264.c
+++ b/drivers/media/v4l2-core/v4l2-h264.c
@@ -50,7 +50,6 @@ v4l2_h264_init_reflist_builder(struct v4l2_h264_reflist_builder *b,
 		if (!(dpb[i].flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
 			continue;
 
-		b->refs[i].pic_num = dpb[i].pic_num;
 		if (dpb[i].flags & V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM)
 			b->refs[i].longterm = true;
 
@@ -139,15 +138,19 @@ static int v4l2_h264_p_ref_list_cmp(const void *ptra, const void *ptrb,
 	}
 
 	/*
-	 * Short term pics in descending pic num order, long term ones in
-	 * ascending order.
+	 * For frames, short term pics are in descending pic num order and long
+	 * term ones in ascending order. For fields, the same direction is used
+	 * but with frame_num (wrapped). For frames, the value of pic_num and
+	 * frame_num are the same (see formula (8-28) and (8-29)). For this
+	 * reason we can use frame_num only and share this funciton between
+	 * frames and fields reflist.
 	 */
 	if (!builder->refs[idxa].longterm)
 		return builder->refs[idxb].frame_num <
 		       builder->refs[idxa].frame_num ?
 		       -1 : 1;
 
-	return builder->refs[idxa].pic_num < builder->refs[idxb].pic_num ?
+	return builder->refs[idxa].frame_num < builder->refs[idxb].frame_num ?
 	       -1 : 1;
 }
 
@@ -173,10 +176,10 @@ static int v4l2_h264_b0_ref_list_cmp(const void *ptra, const void *ptrb,
 			return 1;
 	}
 
-	/* Long term pics in ascending pic num order. */
+	/* Long term pics in ascending frame num order. */
 	if (builder->refs[idxa].longterm)
-		return builder->refs[idxa].pic_num <
-		       builder->refs[idxb].pic_num ?
+		return builder->refs[idxa].frame_num <
+		       builder->refs[idxb].frame_num ?
 		       -1 : 1;
 
 	poca = v4l2_h264_get_poc(builder, ptra);
@@ -218,10 +221,10 @@ static int v4l2_h264_b1_ref_list_cmp(const void *ptra, const void *ptrb,
 			return 1;
 	}
 
-	/* Long term pics in ascending pic num order. */
+	/* Long term pics in ascending frame num order. */
 	if (builder->refs[idxa].longterm)
-		return builder->refs[idxa].pic_num <
-		       builder->refs[idxb].pic_num ?
+		return builder->refs[idxa].frame_num <
+		       builder->refs[idxb].frame_num ?
 		       -1 : 1;
 
 	poca = v4l2_h264_get_poc(builder, ptra);
diff --git a/include/media/v4l2-h264.h b/include/media/v4l2-h264.h
index 4cef717b3f18..0d9eaa956123 100644
--- a/include/media/v4l2-h264.h
+++ b/include/media/v4l2-h264.h
@@ -18,7 +18,6 @@
  * @refs.top_field_order_cnt: top field order count
  * @refs.bottom_field_order_cnt: bottom field order count
  * @refs.frame_num: reference frame number
- * @refs.pic_num: reference picture number
  * @refs.longterm: set to true for a long term reference
  * @refs: array of references
  * @cur_pic_order_count: picture order count of the frame being decoded
@@ -36,7 +35,6 @@ struct v4l2_h264_reflist_builder {
 		s32 top_field_order_cnt;
 		s32 bottom_field_order_cnt;
 		int frame_num;
-		u32 pic_num;
 		u16 longterm : 1;
 	} refs[V4L2_H264_NUM_DPB_ENTRIES];
 
-- 
2.34.1