linux-kernel - Re: [PATCH v1 04/24] media: h264: Store current picture fields

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Date:   Tue, 29 Mar 2022 11:07:31 +0200
From:   Sebastian Fricke <sebastian.fricke@...labora.com>
To:     Nicolas Dufresne <nicolas.dufresne@...labora.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>, kernel@...labora.com,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 04/24] media: h264: Store current picture fields

Hey Nicolas,

On 28.03.2022 15:59, Nicolas Dufresne wrote:
>This information, also called picture structure will be needed to construct

s/picture structure/picture structure,/
(minor.. but still ;))

>reference list when decoding field.

s/will be needed to construct reference list when decoding field./
   is required in field decoding mode to construct 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 | 10 +++++++---
> include/media/v4l2-h264.h           |  4 ++++
> 2 files changed, 11 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/media/v4l2-core/v4l2-h264.c b/drivers/media/v4l2-core/v4l2-h264.c
>index aebed1cbe05a..4c6bfb057bda 100644
>--- a/drivers/media/v4l2-core/v4l2-h264.c
>+++ b/drivers/media/v4l2-core/v4l2-h264.c
>@@ -34,13 +34,17 @@ v4l2_h264_init_reflist_builder(struct v4l2_h264_reflist_builder *b,
> 	cur_frame_num = dec_params->frame_num;
>
> 	memset(b, 0, sizeof(*b));
>-	if (!(dec_params->flags & V4L2_H264_DECODE_PARAM_FLAG_FIELD_PIC))
>+	if (!(dec_params->flags & V4L2_H264_DECODE_PARAM_FLAG_FIELD_PIC)) {
> 		b->cur_pic_order_count = min(dec_params->bottom_field_order_cnt,
> 					     dec_params->top_field_order_cnt);
>-	else if (dec_params->flags & V4L2_H264_DECODE_PARAM_FLAG_BOTTOM_FIELD)
>+		b->cur_pic_fields = V4L2_H264_FRAME_REF;
>+	} else if (dec_params->flags & V4L2_H264_DECODE_PARAM_FLAG_BOTTOM_FIELD) {
> 		b->cur_pic_order_count = dec_params->bottom_field_order_cnt;
>-	else
>+		b->cur_pic_fields = V4L2_H264_BOTTOM_FIELD_REF;
>+	} else {
> 		b->cur_pic_order_count = dec_params->top_field_order_cnt;
>+		b->cur_pic_fields = V4L2_H264_TOP_FIELD_REF;
>+	}
>
> 	for (i = 0; i < V4L2_H264_NUM_DPB_ENTRIES; i++) {
> 		u32 pic_order_count;
>diff --git a/include/media/v4l2-h264.h b/include/media/v4l2-h264.h
>index e282fb16ac58..e165a54c68fa 100644
>--- a/include/media/v4l2-h264.h
>+++ b/include/media/v4l2-h264.h
>@@ -21,6 +21,7 @@
>  * @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
>+ * @cur_pic_fields: fields present in the frame being decoded

As there are only three choices:
```
#define V4L2_H264_TOP_FIELD_REF				0x1
#define V4L2_H264_BOTTOM_FIELD_REF			0x2
#define V4L2_H264_FRAME_REF				0x3
```

Maybe it would help to say:
  * @cur_pic_fields: fields present in the frame being decoded (top/bottom/both)

Greetings,
Sebastian

>  * @unordered_reflist: unordered list of references. Will be used to generate
>  *		       ordered P/B0/B1 lists
>  * @num_valid: number of valid references in the refs array
>@@ -36,7 +37,10 @@ struct v4l2_h264_reflist_builder {
> 		u32 pic_num;
> 		u16 longterm : 1;
> 	} refs[V4L2_H264_NUM_DPB_ENTRIES];
>+
> 	s32 cur_pic_order_count;
>+	u8 cur_pic_fields;
>+
> 	struct v4l2_h264_reference unordered_reflist[V4L2_H264_REF_LIST_LEN];
> 	u8 num_valid;
> };
>-- 
>2.34.1
>