Re: [PATCH v2 2/3] media: cedrus: Fix H264 default reference index count

Dne četrtek, 03. oktober 2019 ob 22:28:46 CEST je Paul Kocialkowski 
napisal(a):

Hi,

On Thu 03 Oct 19, 07:16, Jernej Škrabec wrote:

quoted

Dne četrtek, 03. oktober 2019 ob 00:06:50 CEST je Paul Kocialkowski

napisal(a):

quoted

Hi,

On Wed 02 Oct 19, 21:35, Jernej Skrabec wrote:

quoted

Reference index count in VE_H264_PPS should come from PPS control.
However, this is not really important, because reference index count
is
in our case always overridden by that from slice header.

Thanks for the fixup!

Our libva userspace and v4l2-request testing tool currently don't
provide
this, but I have a pending merge request adding it for the hantro so
it's
good to go.

Actually, I think this is just cosmetic and it would work even if it would
be always 0. We always override this number in SHS2 register with
VE_H264_SHS2_NUM_REF_IDX_ACTIVE_OVRD flag and recently there was a patch
merged to clarify that value in slice parameters should be the one that's
set on default value if override flag is not set in bitstream:
https://git.linuxtv.org/media_tree.git/commit/?
id=187ef7c5c78153acdce8c8714e5918b1018c710b

Well, we could always compare default and value in slice parameters, but I
really don't see the benefit of doing that extra work.

Thanks for the detailed explanation! So I just realized that for HEVC, I
didn't even include the default value in PPS and only went for the
per-slice value. The HEVC hardware block apparently only needs the fields
once at slice level, and by looking at the spec, only one of the two set of
fields will be used.

So perhaps we could do the same for H.264 and only have the set of fields
once in the slice params, so that both codecs are consistent. Userspace can
just check the flag to know whether it should put the PPS default or
slice-specific value in the slice-specific control.

What do you think?

I think that there would be less confusion if only value in slice params would 
exists. But since Philipp rather made clarification in documentation, maybe he 
sees benefit having both values?

Best regards,
Jernej

Cheers,

Paul

quoted

Best regards,
Jernej

quoted

Acked-by: Paul Kocialkowski <redacted>

Cheers,

Paul

quoted

Signed-off-by: Jernej Skrabec <redacted>
---

 drivers/staging/media/sunxi/cedrus/cedrus_h264.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c

b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c index
bd848146eada..4a0e69855c7f 100644

--- a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c

@@ -364,12 +364,8 @@ static void cedrus_set_params(struct cedrus_ctx

*ctx,

 	// picture parameters
 	reg = 0;

-	/*
-	 * FIXME: the kernel headers are allowing the default value to
-	 * be passed, but the libva doesn't give us that.
-	 */
-	reg |= (slice->num_ref_idx_l0_active_minus1 & 0x1f) << 10;
-	reg |= (slice->num_ref_idx_l1_active_minus1 & 0x1f) << 5;
+	reg |= (pps->num_ref_idx_l0_default_active_minus1 & 0x1f) << 10;
+	reg |= (pps->num_ref_idx_l1_default_active_minus1 & 0x1f) << 5;

 	reg |= (pps->weighted_bipred_idc & 0x3) << 2;
 	if (pps->flags & V4L2_H264_PPS_FLAG_ENTROPY_CODING_MODE)
 	
 		reg |= VE_H264_PPS_ENTROPY_CODING_MODE;

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