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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 01BE4C433DB for ; Fri, 26 Mar 2021 16:45:25 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7101761A27 for ; Fri, 26 Mar 2021 16:45:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7101761A27 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 1100B166E; Fri, 26 Mar 2021 17:44:31 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 1100B166E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1616777121; bh=bY6cNo4Qv+bZ/wzcm+QxJ6q6VokYAr2y8KoBrNBD5Vc=; h=Date:From:To:Subject:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=OqTFuLusBoX5qBcnYk6aUleC1eJljtiYMxncp1QmQPRMY4vbK7TastKPfQ03bRWG+ iWducLmKlh/OmAt7VbGAi4ejIovy5fogzzpgqGj//EdRHeleUpD2TkM0ezNogxL4hW eM1yxJ9ayAJoACGHkchesf27u0bTS10GCaeNgW/8= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 7AF4AF80156; Fri, 26 Mar 2021 17:44:30 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 29630F8016B; Fri, 26 Mar 2021 17:44:29 +0100 (CET) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 29D19F80104 for ; Fri, 26 Mar 2021 17:44:19 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 29D19F80104 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id A2D87AC6A; Fri, 26 Mar 2021 16:44:16 +0000 (UTC) Date: Fri, 26 Mar 2021 17:44:16 +0100 Message-ID: From: Takashi Iwai To: David Henningsson Subject: Re: [PATCH v2] sound: rawmidi: Add framing mode In-Reply-To: <2ca71809-9872-bfee-c19d-76b6ce143212@diwic.se> References: <20210324054253.34642-1-coding@diwic.se> <20210324124430.GA3711@workstation> <057ef387-9ee1-2678-29ce-d644f2a3a90a@diwic.se> <20210326044615.GA51246@workstation> <2ca71809-9872-bfee-c19d-76b6ce143212@diwic.se> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Cc: alsa-devel@alsa-project.org X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Fri, 26 Mar 2021 17:29:04 +0100, David Henningsson wrote: > > > But actually I'd like to see some measurement how much we can improve > > the timestamp accuracy by shifting the post office. This may show > > interesting numbers. > > Sorry, I don't know the idiom "shifting the post office" and neither > does the urban dictionary, so I have no idea what this means. :-) It was just joking; you basically moved the place to stamp the incoming data from one place (at the delivery center of a sequencer event) to another earlier place (at the irq handler). The question is: how much time difference have you measured by this move? > > Also, one thing to be more considered is the support for MIDI v2 in > > future. I haven't seen any development so far (and no device > > available around), so I cannot comment on this much more, but it'd be > > worth to take a quick look before defining the solid API/ABI. > > I had a quick look at MIDI 2.0. It offers something called "Jitter > reduction timestamps". After some searching I found that its > resolution is 16 bit, and in units of 1/31250 seconds [1]. So the > suggested timestamp format of secs + nsecs would suit us well for that > case, I believe. When implemented, MIDI 2.0 jitter reduction > timestamps would be another clock ID on top of the existing frame > format (or a new frame format, if we prefer). > > A midi 2.0 UMP (Universal Midi Packet) seems to be 4, 8, 12 or 16 > bytes, excluding the timestamp. If we want to fit that format with the > existing patch, we could increase the frame to 32 bytes so we can fit > more data per packet. Do you think we should do that? Otherwise I > think Patch v3 is ready for merging. Let's evaluate a bit what would be the best fit. I see no big reason to rush the merge right now. thanks, Takashi > > // David > > [1] https://imitone.com/discover-midi/ >