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, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 89AF5C07E98 for ; Mon, 5 Jul 2021 04:30:31 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 447D761350 for ; Mon, 5 Jul 2021 04:30:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 447D761350 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bugs.launchpad.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:45258 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m0GFa-0008JR-CM for qemu-devel@archiver.kernel.org; Mon, 05 Jul 2021 00:30:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38964) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m0GBX-0003oV-3r for qemu-devel@nongnu.org; Mon, 05 Jul 2021 00:26:19 -0400 Received: from indium.canonical.com ([91.189.90.7]:49182) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1m0GBS-0002ta-Sg for qemu-devel@nongnu.org; Mon, 05 Jul 2021 00:26:18 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.93 #5 (Debian)) id 1m0GBO-0004RW-Az for ; Mon, 05 Jul 2021 04:26:10 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id DAAC42E826F for ; Mon, 5 Jul 2021 04:25:59 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Mon, 05 Jul 2021 04:17:26 -0000 From: Launchpad Bug Tracker <1861458@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=Expired; importance=Undecided; assignee=None; X-Launchpad-Bug-Tags: audio X-Launchpad-Bug-Information-Type: Public X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: no X-Launchpad-Bug-Commenters: janitor noah-bergbauer th-huth X-Launchpad-Bug-Reporter: Noah Bergbauer (noah-bergbauer) X-Launchpad-Bug-Modifier: Launchpad Janitor (janitor) References: <158042156192.19296.13362308580628501069.malonedeb@gac.canonical.com> Message-Id: <162545864659.12677.1193185253925647114.malone@loganberry.canonical.com> Subject: [Bug 1861458] Re: Clock drift issue with -soundhw hda X-Launchpad-Message-Rationale: Subscriber (QEMU) @qemu-devel-ml X-Launchpad-Message-For: qemu-devel-ml Precedence: bulk X-Generated-By: Launchpad (canonical.com); Revision="c7d3f30bfe7d7b488c7f9d3c8d7880184b1d065e"; Instance="production" X-Launchpad-Hash: 9ab7143929e6d646d1aa373f7622817381857654 Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com X-Spam_score_int: -66 X-Spam_score: -6.7 X-Spam_bar: ------ X-Spam_report: (-6.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Bug 1861458 <1861458@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" [Expired for QEMU because there has been no activity for 60 days.] ** Changed in: qemu Status: Incomplete =3D> Expired -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1861458 Title: Clock drift issue with -soundhw hda Status in QEMU: Expired Bug description: Here's the scenario: I'm working on code for loopback audio recording (i.e. recording what you're hearing) using WASAPI on Windows. As I usually develop on Linux, I'm using qemu to test this on a Windows 10 VM. The heart of WASAPI audio recording is the IAudioCaptureClient::GetBuffer function (https://docs.microsoft.com /en-us/windows/win32/api/audioclient/nf-audioclient- iaudiocaptureclient-getbuffer). Among other things, this function produces a timestamp for when the audio buffer it returned is supposed to be played. When the audio device in question is the qemu hda device, this timestamp is wrong. There is a clock drift error (I measured it to be about 0.1%, i.e. 1ms drift every second =3D a full second after 16 minutes) that causes the audio clock to advance faster than the system clock. Paradoxically, this does not affect audio playback through qemu at all, no delay there. Only the timestamps returned to recording applications are completely bogus. Unfortunately I'm not intimately familiar with the inner workings of Intel HD Audio. All I can tell you is that this timestamp is supposedly obtained directly from the hardware (which would be qemu in this case), which is also why e.g. chromium implements a workaround for buggy hardware that returns incorrect timestamps. Here are the relevant parts of my command line (version 4.2.0): -enable-kvm -machine pc-q35-3.1,kernel-irqchip=3Don -cpu host,kvm=3Doff,h= v_time,hv_relaxed,hv_vapic,hv_spinlocks=3D0x1fff,hv_vendor_id=3DNvidiaFuckU= -rtc base=3Dlocaltime -nodefaults -soundhw hda Just wanted to let you know about this because it took me three days of utter confusion and frustration to figure this out. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1861458/+subscriptions