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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 128D0C76196 for ; Tue, 11 Apr 2023 07:45:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230093AbjDKHp3 (ORCPT ); Tue, 11 Apr 2023 03:45:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33074 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230224AbjDKHpO (ORCPT ); Tue, 11 Apr 2023 03:45:14 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 41EF21BD1; Tue, 11 Apr 2023 00:45:12 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D0A2061D0C; Tue, 11 Apr 2023 07:45:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E81C0C433D2; Tue, 11 Apr 2023 07:45:09 +0000 (UTC) Message-ID: <5649adcd-3afe-e413-2eac-a92c78427dc9@xs4all.nl> Date: Tue, 11 Apr 2023 09:45:07 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v1] media: vivid: Add webcam parameter for (un)limited bandwidth Content-Language: en-US To: Max Staudt , Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Ricardo Ribalda , Yunke Cao , Tomasz Figa References: <20230410063356.3894767-1-mstaudt@chromium.org> <20230410102350.382f7d02@sal.lan> <6aafad18-13a2-ef45-48a1-1f094554af31@chromium.org> <6ee01cf1-5a8b-081f-e218-8c7da39343bc@xs4all.nl> From: Hans Verkuil In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/04/2023 09:31, Max Staudt wrote: > On 4/11/23 16:26, Hans Verkuil wrote: >> I think we either use this bandwidth option and calculate the max fps based on >> that (basically the bandwidth divided by (image_size + some blanking factor)), >> or we keep it simple and instead of going down two steps in fps we allow up to >> 60 fps up to 720p, then 30 fps for 1080p and 15 fps for 4k. >> >> The fps values currently used are a bit outdated w.r.t. modern webcams, so >> upgrading it wouldn't hurt. And this is a lot simpler than doing bandwidth >> calculations. > > Do I understand you correctly, are you suggesting to simply update the FPS limits to a new fixed schema, and not have an option at all? Correct. The ideal solution is indeed proper bandwidth calculations, since this would be a proper emulation of actual webcam hardware. If you have time and are interested in doing the work, then that would be great, of course. But if you just want to increase the fps limits to be more in line with modern webcams, then that's much quicker and should be fine. It might also be interesting to perhaps allow for 120 fps for the low resolutions (below 720p). Regards, Hans > > I'm happy to prepare an alternative patch for that, too. > > > > Max >