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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham 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 A8555C282C3 for ; Tue, 22 Jan 2019 08:06:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7941B2084C for ; Tue, 22 Jan 2019 08:06:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727524AbfAVIGA (ORCPT ); Tue, 22 Jan 2019 03:06:00 -0500 Received: from lb2-smtp-cloud7.xs4all.net ([194.109.24.28]:48553 "EHLO lb2-smtp-cloud7.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727165AbfAVIGA (ORCPT ); Tue, 22 Jan 2019 03:06:00 -0500 Received: from [192.168.2.10] ([212.251.195.8]) by smtp-cloud7.xs4all.net with ESMTPA id lr4EgkddxBDyIlr4HgSm6x; Tue, 22 Jan 2019 09:05:58 +0100 Subject: Re: [PATCH v2] media: docs-rst: Document m2m stateless video decoder interface To: Alexandre Courbot , Tomasz Figa , Paul Kocialkowski , Maxime Ripard , Mauro Carvalho Chehab , Pawel Osciak , linux-media@vger.kernel.org Cc: linux-kernel@vger.kernel.org References: <20190122062616.164838-1-acourbot@chromium.org> From: Hans Verkuil Message-ID: <9c6ceddc-62c4-e4e7-9e27-b8213d8adb42@xs4all.nl> Date: Tue, 22 Jan 2019 09:05:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20190122062616.164838-1-acourbot@chromium.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfFN+05/CpeswRCtOqgbdRuEGa0RoMps27PYWJR/qbFL/iKmLbs9yf3s6RjDuqLMTbtM7j5TBbVk3H7Mh+KhJav4/oiXyC+WPLF21V+dGZGbZsM5a7owb M0kvjJ8eE8jAVCY9837x9knCK3R7LsnTlY4DruHzt2AmGLfZ88GtYJPQzv1IIv+5YRLeRLG384l0TSKeq5FzhZv6feWkBHRCJ+ffrWTQ+plm2vyU7Ztkadmg 3kbRXskBMbOXVu/DUu8e2q7zBCJDaeLIOdAfGLrT3J4mvwf+PN/Lxiprapl9K20x++Vu9g3zPfKT+0ZpcBG7OwyMShTeuHyYvfmjE3mqf9dqwxFEhlX+GOFb sWRFP8bcxVJGmQ4BHY/cRlMi6yrvSrGX9DZPld8VDwt7n18N3L4/lEGeeB3ys6/IRge0YG7f Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/22/2019 07:26 AM, Alexandre Courbot wrote: > Documents the protocol that user-space should follow when > communicating with stateless video decoders. > > The stateless video decoding API makes use of the new request and tags > APIs. While it has been implemented with the Cedrus driver so far, it > should probably still be considered staging for a short while. > > Signed-off-by: Alexandre Courbot > --- > Changes since v1: > > * Use timestamps instead of tags to reference frames, > * Applied Paul's suggestions to not require one frame worth of data per OUTPUT > buffer > > One of the effects of requiring sub-frame units to be submitted per request is > that the stateless decoders are not exactly "stateless" anymore: if a frame is > made of several slices, then the decoder must keep track of the buffer in which > the current frame is being decoded between requests, and all the slices for the > current frame must be submitted before we can consider decoding the next one. > > Also if we decide to force clients to submit one slice per request, then doesn't > some of the H.264 controls need to change? For instance, in the current v2 > there is still a v4l2_ctrl_h264_decode_param::num_slices member. It is used in > Chromium to specify the number of slices given to the > V4L2_CID_MPEG_VIDEO_H264_SLICE_PARAMS control, but is apparently ignored by the > Cedrus driver. Maxime, can you comment on this? > > Documentation/media/uapi/v4l/dev-codec.rst | 5 + > .../media/uapi/v4l/dev-stateless-decoder.rst | 378 ++++++++++++++++++ > 2 files changed, 383 insertions(+) > create mode 100644 Documentation/media/uapi/v4l/dev-stateless-decoder.rst > Thank you! I have uploaded a version of the V4L2 spec with this and the two older stateful codec patches applied: https://hverkuil.home.xs4all.nl/codec-api/uapi/v4l/dev-codec.html Regards, Hans