On Mon, 9 Sep 2019 09:28:15 +0200
Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> wrote:
> Step '8.2.4.1 Decoding process for picture numbers' was missing in the
> reflist creation logic, leading to invalid P reflists when a
> ->frame_num wraparound happens.
>
> Fixes: a9471e25629b ("media: hantro: Add core bits to support H264 decoding")
> Reported-by: Francois Buergisser <fbuergisser@xxxxxxxxxx>
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> ---
For those who would like to test this patch, here is a video [1] showing
artifacts without this change.
[1]http://crosvideo.commondatastorage.googleapis.com/1080.mp4
> drivers/staging/media/hantro/hantro_h264.c | 23 +++++++++++++++++++++-
> 1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/media/hantro/hantro_h264.c b/drivers/staging/media/hantro/hantro_h264.c
> index 881d73977ff6..e3f757a7de34 100644
> --- a/drivers/staging/media/hantro/hantro_h264.c
> +++ b/drivers/staging/media/hantro/hantro_h264.c
> @@ -271,6 +271,7 @@ struct hantro_h264_reflist_builder {
> const struct v4l2_h264_dpb_entry *dpb;
> s32 pocs[HANTRO_H264_DPB_SIZE];
> u8 unordered_reflist[HANTRO_H264_DPB_SIZE];
> + int frame_nums[HANTRO_H264_DPB_SIZE];
> s32 curpoc;
> u8 num_valid;
> };
> @@ -294,13 +295,20 @@ static void
> init_reflist_builder(struct hantro_ctx *ctx,
> struct hantro_h264_reflist_builder *b)
> {
> + const struct v4l2_ctrl_h264_slice_params *slice_params;
> const struct v4l2_ctrl_h264_decode_params *dec_param;
> + const struct v4l2_ctrl_h264_sps *sps;
> struct vb2_v4l2_buffer *buf = hantro_get_dst_buf(ctx);
> const struct v4l2_h264_dpb_entry *dpb = ctx->h264_dec.dpb;
> struct vb2_queue *cap_q = &ctx->fh.m2m_ctx->cap_q_ctx.q;
> + int cur_frame_num, max_frame_num;
> unsigned int i;
>
> dec_param = ctx->h264_dec.ctrls.decode;
> + slice_params = &ctx->h264_dec.ctrls.slices[0];
> + sps = ctx->h264_dec.ctrls.sps;
> + max_frame_num = 1 << (sps->log2_max_frame_num_minus4 + 4);
> + cur_frame_num = slice_params->frame_num;
>
> memset(b, 0, sizeof(*b));
> b->dpb = dpb;
> @@ -318,6 +326,18 @@ init_reflist_builder(struct hantro_ctx *ctx,
> continue;
>
> buf = to_vb2_v4l2_buffer(vb2_get_buffer(cap_q, buf_idx));
> +
> + /*
> + * Handle frame_num wraparound as described in section
> + * '8.2.4.1 Decoding process for picture numbers' of the spec.
> + * TODO: This logic will have to be adjusted when we start
> + * supporting interlaced content.
> + */
> + if (dpb[i].frame_num > cur_frame_num)
> + b->frame_nums[i] = (int)dpb[i].frame_num - max_frame_num;
> + else
> + b->frame_nums[i] = dpb[i].frame_num;
> +
> b->pocs[i] = get_poc(buf->field, dpb[i].top_field_order_cnt,
> dpb[i].bottom_field_order_cnt);
> b->unordered_reflist[b->num_valid] = i;
> @@ -353,7 +373,8 @@ static int p_ref_list_cmp(const void *ptra, const void *ptrb, const void *data)
> * ascending order.
> */
> if (!(a->flags & V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM))
> - return HANTRO_CMP(b->frame_num, a->frame_num);
> + return HANTRO_CMP(builder->frame_nums[idxb],
> + builder->frame_nums[idxa]);
>
> return HANTRO_CMP(a->pic_num, b->pic_num);
> }
