From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [46.235.227.227]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 288495398; Mon, 28 Feb 2022 10:24:56 +0000 (UTC) Received: from [IPV6:2a01:e0a:120:3210:82d4:230a:70ff:cde0] (unknown [IPv6:2a01:e0a:120:3210:82d4:230a:70ff:cde0]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: benjamin.gaignard) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id BDB6F1F4381D; Mon, 28 Feb 2022 10:24:53 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1646043894; bh=kA6wk9poQowj7pG8o/AcE0UkJDbBr/dkYvIeNp0XXWg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=JhADHZpx2XchL7wRFhLx9u5AdEFzJyh4R4y2hmB/LFpilBHi0RF9NmQCSkY/Z3Fcg 0viETfCyEKPIArjmwBA1drhd9DWUsjnHqdUdd1728mdY551ARSdD0yvKV36gOW1g9x z4dlhpdZa5dyhfT3QxFgbM9HpaJ8dGkgaVeGAOCP8reZLiphJKiaZfANLEPFMD2dAr W43+yfakSqTqkNYemMpsvKxZRdIOGqTyK2FozsbDTjGGzWgudE3xSmhut/0ObtQerK 406AutADF3dKoEc16xMoiMQuVIDRILtR00w1hiSXLEsAGo7qxZ9GAhtWghaOLOLE70 MlGDuKiKBqBDg== Message-ID: <14bd4748-1b73-c102-e98f-933efa34cd3c@collabora.com> Date: Mon, 28 Feb 2022 11:24:51 +0100 Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v3 09/14] media: uapi: Add V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSET control Content-Language: en-US To: John Cox , =?UTF-8?Q?Jernej_=c5=a0krabec?= Cc: mchehab@kernel.org, ezequiel@vanguardiasur.com.ar, p.zabel@pengutronix.de, gregkh@linuxfoundation.org, mripard@kernel.org, paul.kocialkowski@bootlin.com, wens@csie.org, jonas@kwiboo.se, nicolas@ndufresne.ca, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-staging@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev, kernel@collabora.com, knaerzche@gmail.com References: <20220225164600.1044663-1-benjamin.gaignard@collabora.com> <4378293.LvFx2qVVIh@kista> <1884298.PYKUYFuaPT@kista> <7348885.EvYhyI6sBW@kista> From: Benjamin Gaignard In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Le 28/02/2022 à 10:47, John Cox a écrit : > On Sat, 26 Feb 2022 19:17:46 +0100, you wrote: > >> Dne sobota, 26. februar 2022 ob 18:59:18 CET je Jernej Škrabec napisal(a): >>> Hi! >>> >>> Dne petek, 25. februar 2022 ob 20:30:20 CET je Jernej Škrabec napisal(a): >>>> Hi! >>>> >>>> Dne petek, 25. februar 2022 ob 17:45:55 CET je Benjamin Gaignard >> napisal(a): >>>>> The number of 'entry point offset' could be very variable. >>>>> Rather than use a large static array define a v4l2 dynamic array >>>>> of integer control. >>>> I suggest we should be more specific and say U32 (V4L2_CTRL_TYPE_U32). >>>> >>>>> The number of entry point offsets is reported by the elems field. >>> I did few more tests and these are my findings: >>> 1. dynamic array can't be set over size, specified in .dims array >>> 2. entry point offsets are per slice, so if we make slices dynamic array, >> then >>> entry points would become two dimensional dynamic array >>> 3. num_entry_point_offsets must be part of slice control, because it can be >>> zero, but size of array can't be >> Clarification: num_entry_point_offsets is needed in any case, even without entry >> point list. > I thought that at least one decoder wanted the entry points or have we > decided that we don't? Whilst they aren't required for decode, what they > give you, if your h/w supports it, is the ability to decode multiple > lines of CTBs in parallel (with a 2 CTB offset between lines), so they > aren't useless. > > If we do decided we want the entry point offset control, now or later, > then num_entry_points in the slice_param allows you to determine which > offsets apply to which slices without the complexity of a variable array > of variable arrays. > > But whether or not we end up supporting entry point offsets, the Pi h/w > requires me to generate 1 table entry for each CTB line and > num_entry_points is the parameter I need for that, so I really want it > in the slice_params. I'm adding a control (dynamic array) and num_entry_points field in slice parameters in the next version. See here: https://gitlab.collabora.com/benjamin.gaignard/for-upstream/-/commit/6b4efa4dc54de069893f5203d885fea2c1347916 Regards, Benjamin > Regards > > John Cox > >>> 4. fortunately, not setting entry points doesn't impact decoding >> correctness. >>> This is in line what John told me about them. >>> >>> Hans, can you comment points 1-3? I might misunderstand point 1. >>> >>> In short, it seems like we don't really need entry points, even if they are >>> used in BSP library. In both cases, I got fluster score 119/138 (10-bit >>> excluded), so we can just drop this patch, although I'm a bit uneasy not >>> setting entry points... >>> >>> Best regards, >>> Jernej >>> >>>>> Signed-off-by: Benjamin Gaignard >>>>> --- >>>>> .../userspace-api/media/v4l/ext-ctrls-codec.rst | 9 +++++++++ >>>>> include/media/hevc-ctrls.h | 1 + >>>>> 2 files changed, 10 insertions(+) >>>>> >>>>> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/ >>>> Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst >>>>> index 44a268a948c0..71f7dc1c1ccd 100644 >>>>> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst >>>>> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst >>>>> @@ -3128,6 +3128,15 @@ enum v4l2_mpeg_video_hevc_size_of_length_field - >>>>> >>>>> \normalsize >>>>> >>>>> +``V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS (integer)`` >>>> Here you have OFFSETS (plural) ... >>>> >>>>> + Specifies the i-th entry point offset in bytes and is represented by >>>>> + offset_len_minus1 plus 1 bits. >>>> You probably mean entry_point_offset_minus1? offset_len_minus1 just tells >> how >>>> much bits need to be read for each element and it's not important for >> actual >>>> decoding. >>>> >>>>> + This control is a dynamically sized array. The number of entry >> point >>>>> + offsets is reported by the ``elems`` field. >>>>> + This bitstream parameter is defined according to :ref:`hevc`. >>>>> + They are described in section 7.4.7.1 "General slice segment header >>>>> + semantics" of the specification. >>>>> + >>>>> ``V4L2_CID_STATELESS_HEVC_SCALING_MATRIX (struct)`` >>>>> Specifies the HEVC scaling matrix parameters used for the scaling >>>> process >>>>> for transform coefficients. >>>>> diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h >>>>> index 3016c1abb1d0..3f8a67924df3 100644 >>>>> --- a/include/media/hevc-ctrls.h >>>>> +++ b/include/media/hevc-ctrls.h >>>>> @@ -20,6 +20,7 @@ >>>>> #define V4L2_CID_STATELESS_HEVC_DECODE_PARAMS (V4L2_CID_CODEC_BASE + >>>> 1012) >>>>> #define V4L2_CID_STATELESS_HEVC_DECODE_MODE (V4L2_CID_CODEC_BASE + >>>> 1015) >>>>> #define V4L2_CID_STATELESS_HEVC_START_CODE (V4L2_CID_CODEC_BASE >> + >>> 1016) >>>>> +#define V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSET (V4L2_CID_CODEC_BASE >> + >>>> 1017) >>>> >>>> ... and here you have OFFSET (singlular). I suggest plural form to be used >>> in >>>> all places, including subject line of this commit. >>>> >>>> Additionally, it would be nice if control is initialized, like so: >>>> https://github.com/jernejsk/linux-1/commit/ >>>> f938e162cd8dd77c9f6f1b248d80144840a37bce >>>> >>>> Best regards, >>>> Jernej >>>> >>>>> >>>>> /* enum v4l2_ctrl_type type values */ >>>>> #define V4L2_CTRL_TYPE_HEVC_SPS 0x0120 >>>>> -- >>>>> 2.32.0 >>>>> >>>>> >>>> >>>> >>> >>>