From: Ezequiel Garcia <ezequiel@collabora.com>
To: Hans Verkuil <hverkuil@xs4all.nl>,
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 08:43:22 -0300 [thread overview]
Message-ID: <6e61d98bd8d7a6d41daf0edd449bd27558c0ac16.camel@collabora.com> (raw)
In-Reply-To: <bfb5d0df-779f-78d2-fc48-3c6056f5fdd3@xs4all.nl>
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?
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 11:43 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 [this message]
2020-07-16 11:44 ` Hans Verkuil
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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