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From: Alexandre Courbot <acourbot@chromium.org>
To: Ezequiel Garcia <ezequiel@collabora.com>
Cc: Linux Media Mailing List <linux-media@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Tomasz Figa <tfiga@chromium.org>,
	kernel@collabora.com, Jonas Karlman <jonas@kwiboo.se>,
	Hans Verkuil <hverkuil@xs4all.nl>,
	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 08/10] media: uapi: h264: Clean slice invariants syntax elements
Date: Sat, 25 Jul 2020 23:34:00 +0900	[thread overview]
Message-ID: <CAPBb6MVMXeTcUfb-98McYCKjh=eM=BTo2dSY=L1c6dv2jHqXcg@mail.gmail.com> (raw)
In-Reply-To: <20200715202233.185680-9-ezequiel@collabora.com>

On Thu, Jul 16, 2020 at 5:23 AM Ezequiel Garcia <ezequiel@collabora.com> wrote:
>
> The H.264 specification requires in its "Slice header semantics"
> section that the following values shall be the same in all slice headers:
>
>   pic_parameter_set_id
>   frame_num
>   field_pic_flag
>   bottom_field_flag
>   idr_pic_id
>   pic_order_cnt_lsb
>   delta_pic_order_cnt_bottom
>   delta_pic_order_cnt[ 0 ]
>   delta_pic_order_cnt[ 1 ]
>   sp_for_switch_flag
>   slice_group_change_cycle
>
> and can therefore be moved to the per-frame decode parameters control.

I am really not a H.264 expert, so this question may not be relevant,
but are these values specified for every slice header in the
bitstream, or are they specified only once per frame?

I am asking this because it would certainly make user-space code
simpler if we could remain as close to the bitstream as possible. If
these values are specified once per slice, then factorizing them would
leave user-space with the burden of deciding what to do if they change
across slices.

Note that this is a double-edged sword, because it is not necessarily
better to leave the firmware in charge of deciding what to do in such
a case. :) So hopefully these are only specified once per frame in the
bitstream, in which case your proposal makes complete sense.

  reply	other threads:[~2020-07-25 14:34 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
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 [this message]
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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