From owner-freebsd-multimedia@FreeBSD.ORG Thu Apr 22 19:37:00 2010 Return-Path: Delivered-To: freebsd-multimedia@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 58DDB1065687 for ; Thu, 22 Apr 2010 19:37:00 +0000 (UTC) (envelope-from a_best01@uni-muenster.de) Received: from zivm-relay3.uni-muenster.de (ZIVM-RELAY3.UNI-MUENSTER.DE [128.176.192.19]) by mx1.freebsd.org (Postfix) with ESMTP id E04278FC18 for ; Thu, 22 Apr 2010 19:36:59 +0000 (UTC) X-IronPort-AV: E=Sophos;i="4.52,258,1270418400"; d="scan'208";a="31993365" Received: from zivmaildisp1.uni-muenster.de (HELO ZIVMAILUSER03.UNI-MUENSTER.DE) ([128.176.188.85]) by zivm-relay3.uni-muenster.de with ESMTP; 22 Apr 2010 21:25:12 +0200 Received: by ZIVMAILUSER03.UNI-MUENSTER.DE (Postfix, from userid 149459) id 27A1A1B0758; Thu, 22 Apr 2010 21:25:12 +0200 (CEST) Date: Thu, 22 Apr 2010 21:25:11 +0200 (CEST) From: Alexander Best Sender: Organization: Westfaelische Wilhelms-Universitaet Muenster To: Andrew Reilly , Roman Divacky Message-ID: In-Reply-To: <20100422042929.GA79075@duncan.reilly.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: freebsd-multimedia@freebsd.org, freebsd-current@FreeBSD.org Subject: Re: [CFT]: ClangBSD is selfhosting, we need testers now X-BeenThere: freebsd-multimedia@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Multimedia discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Apr 2010 19:37:00 -0000 Andrew Reilly schrieb am 2010-04-22: > On Wed, Apr 21, 2010 at 05:23:38PM +0200, Roman Divacky wrote: > > On Wed, Apr 21, 2010 at 05:20:57PM +0200, Alexander Best wrote: > > > i might have stumbled upon a problem with clang. i've compiled a > > > kernel from > > > the clang branch using `make kernel INSTKERNNAME=clang` and > > > booted from it. > > > i'm now experiencing audio problems with mp3s and certain video > > > files. > > > playback is awfully slow and the audio output gets distorted > > > massively. `top` > > > however reports no high cpu load and `vmstat -i` doesn't report > > > anything > > > unusual either. > > > this problem doesn't occur with a regular gcc-kernel. > > > both kernels are running under a regular (gcc) world. > > > i thought it might be a problem with acpi, but disabling acpi > > > (hint.acpi.0.disabled=1) gives me a system freeze. > > I've heard about this problem but did not manage to reproduce that. > > can you try to bisect what file is being miscompiled? ie. compile > > half of the kernel with gcc and half with clang and bisect this > > way to a single file. > The FreeBSD sound subsystem has a sample-rate converter built > into the feeder that (from a cursory look) is probably quite > carefully tweaked to be able to perform well (or at all). I've > added -multimedia to the CC line, because they're the guys > who are going to know the details. It's possible that some > GCC-specific manifest constants are being tested-for, with > sub-optimal fall-back code being run, instead. > In the mean-time, Alexander, are there any sound-related sysctls > that you can tweak so that the audio playback that you're doing > does *not* involve sample rate conversion? i'm not sure because i'm not an expert on audio stuff. these sysctl vars might contain the functionality you mentioned: hw.snd.feeder_rate_presets: 100:8:0.85 100:36:0.92 100:164:0.97 hw.snd.feeder_rate_polyphase_max: 183040 hw.snd.feeder_rate_min: 1 hw.snd.feeder_rate_max: 2016000 hw.snd.feeder_rate_round: 25 hw.snd.feeder_rate_quality: 1 hw.snd.feeder_eq_presets: PEQ:16000,0.2500,62,0.2500:-9,9,1.0:44100,48000,88200,96000,176400,192000 hw.snd.feeder_eq_exact_rate: 0 > Cheers, -- Alexander Best