Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_MED,SPF_PASS,T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: EATSERVER: mailn 1166; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v1EFv53O029946 for ; Tue, 14 Feb 2017 16:57:07 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cdfP3-0000Sr-12 for rs_out_1@blacksheep.org; Tue, 14 Feb 2017 15:52:29 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cdfP2-0000Si-Eu for rsgb_lf_group@blacksheep.org; Tue, 14 Feb 2017 15:52:28 +0000 Received: from porthos.netcom.co.uk ([217.72.171.73]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1cdfOw-0003Ub-OS for rsgb_lf_group@blacksheep.org; Tue, 14 Feb 2017 15:52:27 +0000 X-DKIM-Result: Domain=abelian.org Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=abelian.org ; s=default; h=Content-Transfer-Encoding:Content-Type:MIME-Version:Date: Message-ID:Subject:From:To:Sender:Reply-To:Cc:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: In-Reply-To:References:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=3ZQLDP+go3fqh1vsOSpXHpmd74MPcv9BNvK5QpNjBe4=; b=O7xl4IvrJ17cXzms8kbtxBX/69 ADMfoX6aVnNO9mQGnbBkxnSnsuAeDg0fy5yr1Ndnr5OpW6eOOTDGa5gHKv7PyoqOa+fuStap87DqT HjtEsvpi1mxduHW0sU2p3Fl1urMpFPf5BbWso1sBXR6pKcHfQEqJLnOTMsVXMxlAKIt0=; Received: from i-194-106-52-83.freedom2surf.net ([194.106.52.83]:42754 helo=pn.abelian.org) by porthos.netcom.co.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.88) (envelope-from ) id 1cdfOw-0001Vi-79 for rsgb_lf_group@blacksheep.org; Tue, 14 Feb 2017 15:52:22 +0000 Received: from [127.0.0.1] (localhost [127.0.0.1]) by pn.abelian.org (Postfix) with ESMTP id 9E468400920 for ; Tue, 14 Feb 2017 15:52:21 +0000 (UTC) To: rsgb_lf_group@blacksheep.org From: Paul Nicholson Message-ID: Date: Tue, 14 Feb 2017 15:52:21 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - porthos.netcom.co.uk X-AntiAbuse: Original Domain - blacksheep.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - abelian.org X-Get-Message-Sender-Via: porthos.netcom.co.uk: authenticated_id: catchall@abelian.org X-Authenticated-Sender: porthos.netcom.co.uk: catchall@abelian.org X-Scan-Signature: c0336009bd9bab526ca27d297ea7579a Subject: LF: Raspberry Pi sound interface that works Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.75 Status: RO X-Status: X-Keywords: X-UID: 10587 USB audio on the Raspberry Pi is pretty useless thanks to lost USB packets. A much better solution for audio is to use the I2S bus via add-on boards such as the Wolfson. Unfortunately the Wolfson never worked with the quad core RPi. I'm just testing another one, called an Audio Injector from Flatmax Studios. It uses the same wm8731 chip as the Wolfson but works with the quad core Pi: http://audioinjector.net/ https://www.amazon.co.uk/gp/product/B01HBC8CJ0/ Runs up to 96k samples/sec stereo in full duplex. Measured input performance is at http://abelian.org/scard (Ignore the two spikes in the noise floor, these are from the neighbour's solar panel. I'll measure the noise again after sunset!) Noise is lower than 1uV in 1Hz and full scale input is quite high, so the dynamic range is great. It runs at 32 bits per sample very nicely. It appears to run real well with ebsynth: http://abelian.org/vlf/tmp/170214b.gif Uses about 11% of one core and appears as good if not better than even a PCI soundcard on a PC! It looks like Flatmax Studios are kick starting development of a multi-channel version with 8 outputs and 6 inputs. If that works it will be great for 3 axis coherent reception with just one Raspberry Pi. Due apparently in April. A lot more testing to do but so far it looks promising. Sorry I just bought the last two from Amazon uk so they're out of stock for the moment! -- Paul Nicholson --