From: Hans Verkuil <hverkuil@xs4all.nl>
To: Ezequiel Garcia <ezequiel@collabora.com>,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Tomasz Figa <tfiga@chromium.org>,
kernel@collabora.com, Jonas Karlman <jonas@kwiboo.se>,
Alexandre Courbot <acourbot@chromium.org>,
Jeffrey Kardatzke <jkardatzke@chromium.org>,
Nicolas Dufresne <nicolas.dufresne@collabora.com>,
Philipp Zabel <p.zabel@pengutronix.de>,
Maxime Ripard <mripard@kernel.org>,
Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Subject: Re: [PATCH 02/10] media: uapi: h264: Further clarify scaling lists order
Date: Thu, 16 Jul 2020 13:44:58 +0200 [thread overview]
Message-ID: <39819dcc-a336-3d13-38ab-93a27460e103@xs4all.nl> (raw)
In-Reply-To: <6e61d98bd8d7a6d41daf0edd449bd27558c0ac16.camel@collabora.com>
On 16/07/2020 13:43, Ezequiel Garcia wrote:
> On Thu, 2020-07-16 at 09:23 +0200, Hans Verkuil wrote:
>> On 15/07/2020 22:22, Ezequiel Garcia wrote:
>>> Commit 0b0393d59eb4a ("media: uapi: h264: clarify
>>> expected scaling_list_4x4/8x8 order") improved the
>>> documentation on H264 scaling lists order.
>>>
>>> This commit improves the documentation by clarifying
>>> that the lists themselves are expected in matrix order.
>>
>> "matrix order" is not a well defined term. Especially since different
>> programming languages lay out matrices differently (e.g. fortran uses
>> column-major order). Perhaps something like this is more unambiguous:
>>
>
> Agreed, "matrix order" is perhaps not a proper choice of words.
>
>> "The values on each scaling list are in row-major order."
>>
>> BTW, why not be explicit and use:
>>
>> __u8 scaling_list_4x4[6][4][4];
>> __u8 scaling_list_8x8[6][8][8];
>>
>> That makes it explicit and the order is just that of what the C language
>> uses.
>>
>
> I am not sure if that'll go in clearer direction.
>
> I'm thinking we just need to clarify the coefficients
> are in raster scan order, as opposed to a zig-zag scan
> order, which is a part of the decoding process.
>
> How about we simply say "raster scan order" and keep the patch as is?
That works for me.
Regards,
Hans
>
> Thanks,
> Ezequiel
>
>
>> Regards,
>>
>> Hans
>>
>>> Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
>>> ---
>>> Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst | 6 ++++--
>>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
>>> index c2e17c02f77e..16bfc98ab2f6 100644
>>> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
>>> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
>>> @@ -1725,12 +1725,14 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
>>> - ``scaling_list_4x4[6][16]``
>>> - Scaling matrix after applying the inverse scanning process.
>>> Expected list order is Intra Y, Intra Cb, Intra Cr, Inter Y,
>>> - Inter Cb, Inter Cr.
>>> + Inter Cb, Inter Cr. The values on each scaling list are
>>> + expected in matrix order.
>>> * - __u8
>>> - ``scaling_list_8x8[6][64]``
>>> - Scaling matrix after applying the inverse scanning process.
>>> Expected list order is Intra Y, Inter Y, Intra Cb, Inter Cb,
>>> - Intra Cr, Inter Cr.
>>> + Intra Cr, Inter Cr. The values on each scaling list are
>>> + expected in matrix order.
>>>
>>> ``V4L2_CID_MPEG_VIDEO_H264_SLICE_PARAMS (struct)``
>>> Specifies the slice parameters (as extracted from the bitstream)
>>>
>
>
next prev parent reply other threads:[~2020-07-16 11:45 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-15 20:22 [PATCH 0/7] media: Clean H264 stateless uAPI Ezequiel Garcia
2020-07-15 20:22 ` [PATCH 01/10] media: uapi: h264: Update reference lists Ezequiel Garcia
2020-07-22 21:43 ` Jonas Karlman
2020-07-15 20:22 ` [PATCH 02/10] media: uapi: h264: Further clarify scaling lists order Ezequiel Garcia
2020-07-16 7:23 ` Hans Verkuil
2020-07-16 11:43 ` Ezequiel Garcia
2020-07-16 11:44 ` Hans Verkuil [this message]
2020-07-15 20:22 ` [PATCH 03/10] media: uapi: h264: Split prediction weight parameters Ezequiel Garcia
2020-07-16 7:26 ` Hans Verkuil
2020-07-16 11:14 ` Ezequiel Garcia
2020-07-22 16:03 ` Jernej Škrabec
2020-07-25 13:30 ` Alexandre Courbot
2020-07-30 13:48 ` Nicolas Dufresne
2020-07-15 20:22 ` [PATCH 04/10] media: uapi: h264: Clarify pic_order_cnt_bit_size field Ezequiel Garcia
2020-07-15 20:22 ` [PATCH 05/10] media: uapi: h264: Increase size of 'first_mb_in_slice' field Ezequiel Garcia
2020-07-15 20:22 ` [PATCH 06/10] media: uapi: h264: Cleanup DPB entry interface Ezequiel Garcia
2020-07-22 16:09 ` Jernej Škrabec
2020-07-22 17:11 ` Ezequiel Garcia
2020-07-22 21:52 ` Jonas Karlman
2020-07-24 19:08 ` Ezequiel Garcia
2020-07-27 23:39 ` Jonas Karlman
2020-07-31 12:49 ` Ezequiel Garcia
2020-07-15 20:22 ` [PATCH 07/10] media: uapi: h264: Increase size of DPB entry pic_num Ezequiel Garcia
2020-07-15 20:22 ` [PATCH 08/10] media: uapi: h264: Clean slice invariants syntax elements Ezequiel Garcia
2020-07-25 14:34 ` Alexandre Courbot
2020-07-27 14:39 ` Ezequiel Garcia
2020-07-27 14:52 ` Tomasz Figa
2020-07-27 16:18 ` Ezequiel Garcia
2020-07-27 18:10 ` Tomasz Figa
2020-07-27 19:43 ` Nicolas Dufresne
2020-08-04 13:35 ` Tomasz Figa
2020-08-05 16:41 ` Ezequiel Garcia
2020-07-28 12:44 ` Maxime Ripard
2020-07-28 21:09 ` Nicolas Dufresne
2020-07-15 20:22 ` [PATCH 09/10] media: hantro: Don't require unneeded H264_SLICE_PARAMS Ezequiel Garcia
2020-07-25 14:45 ` Alexandre Courbot
2020-07-26 13:34 ` Alexandre Courbot
2020-07-27 14:44 ` Ezequiel Garcia
2020-07-15 20:22 ` [PATCH 10/10] media: rkvdec: " Ezequiel Garcia
2020-07-27 22:03 ` Jonas Karlman
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