From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07E9FC31E40 for ; Mon, 12 Aug 2019 11:59:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CFB97206DF for ; Mon, 12 Aug 2019 11:59:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728245AbfHLL7P (ORCPT ); Mon, 12 Aug 2019 07:59:15 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:56380 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728216AbfHLL7O (ORCPT ); Mon, 12 Aug 2019 07:59:14 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: ezequiel) with ESMTPSA id 8F78728AC52 Message-ID: <1d1ff6c5943c462f38235e4b003eff5ab65dbbd0.camel@collabora.com> Subject: Re: [PATCH v4 03/11] media: uapi: h264: Add the concept of decoding mode From: Ezequiel Garcia To: Hans Verkuil , linux-media@vger.kernel.org Cc: kernel@collabora.com, Nicolas Dufresne , Tomasz Figa , linux-rockchip@lists.infradead.org, Heiko Stuebner , Jonas Karlman , Philipp Zabel , Boris Brezillon , Paul Kocialkowski , Alexandre Courbot , fbuergisser@chromium.org, linux-kernel@vger.kernel.org Date: Mon, 12 Aug 2019 08:59:02 -0300 In-Reply-To: References: <20190808103432.12062-1-ezequiel@collabora.com> <20190808103432.12062-4-ezequiel@collabora.com> Organization: Collabora Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5-1.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Mon, 2019-08-12 at 12:19 +0200, Hans Verkuil wrote: > On 8/8/19 12:34 PM, Ezequiel Garcia wrote: > > From: Boris Brezillon > > > > Some stateless decoders don't support per-slice decoding granularity > > (or at least not in a way that would make them efficient or easy to use). > > > > Expose a menu to control the supported decoding modes. Drivers are > > allowed to support only one decoding but they can support both too. > > > > Signed-off-by: Boris Brezillon > > Reviewed-by: Paul Kocialkowski > > --- > > Changes in v4: > > * Typos/rewording fixes > > > > Changes in v3: > > * s/per-{slice,frame} decoding/{slice,frame}-based decoding/ > > * Add Paul's R-b > > > > Changes in v2: > > * Allow decoding multiple slices in per-slice decoding mode > > * Minor doc improvement/fixes > > --- > > .../media/uapi/v4l/ext-ctrls-codec.rst | 43 ++++++++++++++++++- > > drivers/media/v4l2-core/v4l2-ctrls.c | 9 ++++ > > include/media/h264-ctrls.h | 11 +++++ > > 3 files changed, 62 insertions(+), 1 deletion(-) > > > > diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > > index c5f39dd50043..ea0455957149 100644 > > --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > > +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > > @@ -1747,6 +1747,11 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type - > > * - __u32 > > - ``size`` > > - > > + * - __u32 > > + - ``start_byte_offset`` > > + - Where the slice payload starts in the output buffer. Useful when the > > + OUTPUT buffer contains more than one slice (some codecs need to know > > + where each slice starts in this buffer). > > * - __u32 > > - ``header_bit_size`` > > - > > @@ -1930,7 +1935,10 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type - > > - > > * - __u16 > > - ``num_slices`` > > - - Number of slices needed to decode the current frame > > + - Number of slices needed to decode the current frame/field. When > > + operating in slice-based decoding mode (see > > + :c:type:`v4l2_mpeg_video_h264_decoding_mode`), this field > > + should always be set to one. > > * - __u16 > > - ``nal_ref_idc`` > > - NAL reference ID value coming from the NAL Unit header > > @@ -2021,6 +2029,39 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type - > > - 0x00000004 > > - The DPB entry is a long term reference frame > > > > +``V4L2_CID_MPEG_VIDEO_H264_DECODING_MODE (enum)`` > > + Specifies the decoding mode to use. Currently exposes slice-based and > > + frame-based decoding but new modes might be added later on. > > + Drivers may expose a single or multiple decoding modes, > > + depending on what they can support. > > This should mention that this is valid for V4L2_PIX_FMT_H264_SLICE pixelformat > only. And it is a required control (i.e. it must always be present for that > pixelformat). Ditto for the start code control. > > Also, the V4L2_PIX_FMT_H264_SLICE should refer to this control and the start > code control as well since these controls effectively are modifiers for the > pixelformat. > Right, this makes perfect sense. > > + > > + .. note:: > > + > > + This menu control is not yet part of the public kernel API and > > + it is expected to change. > > + > > +.. c:type:: v4l2_mpeg_video_h264_decoding_mode > > + > > +.. cssclass:: longtable > > + > > +.. flat-table:: > > + :header-rows: 0 > > + :stub-columns: 0 > > + :widths: 1 1 2 > > + > > + * - ``V4L2_MPEG_VIDEO_H264_SLICE_BASED_DECODING`` > > + - 0 > > + - The decoding is done at the slice granularity. > > + v4l2_ctrl_h264_decode_params->num_slices should be set to 1. > > + The OUTPUT buffer must contain a single slice. > > + * - ``V4L2_MPEG_VIDEO_H264_FRAME_BASED_DECODING`` > > + - 1 > > + - The decoding is done at the frame granularity. > > + v4l2_ctrl_h264_decode_params->num_slices should be set to the number of > > + slices forming a frame. > > Actually, I wonder if there shouldn't be a third option: FIELD_BASED_DECODING > to indicate that the hardware expects the slices of a single field in a buffer > instead of both fields. > > Or just stick to FRAME_BASED_DECODING for now but explicitly mention that > in the case of interlaced decoding both fields must be present in the buffer. > OK. > A FIELD_BASED_DECODING option can always be added later if necessary. > Thanks, Ezequiel