From owner-freebsd-questions@freebsd.org Fri Apr 24 08:06:45 2020 Return-Path: Delivered-To: freebsd-questions@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id D668D2ABB3E for ; Fri, 24 Apr 2020 08:06:45 +0000 (UTC) (envelope-from 4250.82.1d4c100038be914.93016ee4d2db4499c9f14af20c4de270@email-od.com) Received: from s1-b0c6.socketlabs.email-od.com (s1-b0c6.socketlabs.email-od.com [142.0.176.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 497mwN5kfXz4128 for ; Fri, 24 Apr 2020 08:06:44 +0000 (UTC) (envelope-from 4250.82.1d4c100038be914.93016ee4d2db4499c9f14af20c4de270@email-od.com) DKIM-Signature: v=1; a=rsa-sha256; d=email-od.com;i=@email-od.com;s=dkim; c=relaxed/relaxed; q=dns/txt; t=1587715605; x=1590307605; h=content-transfer-encoding:content-type:mime-version:references:in-reply-to:message-id:subject:cc:to:from:date:x-thread-info; bh=ooT3dmsMMKejMXBNFCtCXLCMV2Nbi7U+0AHB5RNUlK4=; b=dOvywS13Sziy5iSfbgetP3bGLDYh3W7TO1MG8dlRqkmqSk34jkry750M85ThXTHvYkiu1XcrLGOrhDnKrL83ULJuTHM+g3Udtb5CsbUlMLTCjg2Hlx85I2Ibn/52pu1mf2eUU8cJYnbfgoLh4tPeAnUiY6a7qJ1V+tE8XWti3IU= X-Thread-Info: NDI1MC45Mi4xZDRjMTAwMDM4YmU5MTQuZnJlZWJzZC1xdWVzdGlvbnM9ZnJlZWJzZC5vcmc= Received: from r1.us-east-1.aws.in.socketlabs.com (r1.us-east-1.aws.in.socketlabs.com [142.0.191.1]) by mxsg2.email-od.com with ESMTP(version=Tls12 cipher=Aes256 bits=256); Fri, 24 Apr 2020 04:06:38 -0400 Received: from smtp.lan.sohara.org (EMTPY [185.202.17.215]) by r1.us-east-1.aws.in.socketlabs.com with ESMTP(version=Tls12 cipher=Aes256 bits=256); Fri, 24 Apr 2020 04:06:36 -0400 Received: from [192.168.63.1] (helo=steve.lan.sohara.org) by smtp.lan.sohara.org with smtp (Exim 4.92.3 (FreeBSD)) (envelope-from ) id 1jRtM3-0001Um-LQ; Fri, 24 Apr 2020 09:06:35 +0100 Date: Fri, 24 Apr 2020 09:06:35 +0100 From: Steve O'Hara-Smith To: Polytropon Cc: FreeBSD Questions Subject: Re: Audio recording on demand (level + duration) Message-Id: <20200424090635.1041850d0bc1ebdee783678d@sohara.org> In-Reply-To: <20200423175126.e9eea9fb.freebsd@edvax.de> References: <20200423175126.e9eea9fb.freebsd@edvax.de> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; amd64-portbld-freebsd12.0) X-Clacks-Overhead: "GNU Terry Pratchett" Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 497mwN5kfXz4128 X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=pass header.d=email-od.com header.s=dkim header.b=dOvywS13; dmarc=none; spf=pass (mx1.freebsd.org: domain of 4250.82.1d4c100038be914.93016ee4d2db4499c9f14af20c4de270@email-od.com designates 142.0.176.198 as permitted sender) smtp.mailfrom=4250.82.1d4c100038be914.93016ee4d2db4499c9f14af20c4de270@email-od.com X-Spamd-Result: default: False [-1.64 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-0.98)[-0.978,0]; R_DKIM_ALLOW(-0.20)[email-od.com:s=dkim]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(-0.20)[+ip4:142.0.176.0/20]; MV_CASE(0.50)[]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[sohara.org]; NEURAL_HAM_LONG(-1.00)[-0.995,0]; RCVD_COUNT_THREE(0.00)[4]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[email-od.com:+]; RCPT_COUNT_TWO(0.00)[2]; RCVD_IN_DNSWL_NONE(0.00)[198.176.0.142.list.dnswl.org : 127.0.15.0]; IP_SCORE(0.03)[ip: (-0.22), ipnet: 142.0.176.0/22(0.31), asn: 7381(0.12), country: US(-0.05)]; FORGED_SENDER(0.30)[steve@sohara.org,4250.82.1d4c100038be914.93016ee4d2db4499c9f14af20c4de270@email-od.com]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_LAST(0.00)[]; ASN(0.00)[asn:7381, ipnet:142.0.176.0/22, country:US]; FROM_NEQ_ENVFROM(0.00)[steve@sohara.org,4250.82.1d4c100038be914.93016ee4d2db4499c9f14af20c4de270@email-od.com]; MID_RHS_MATCH_FROM(0.00)[] X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 24 Apr 2020 08:06:45 -0000 On Thu, 23 Apr 2020 17:51:26 +0200 Polytropon wrote: > My question is: > > What file can I monitor (and how) to obtain an information > about _if_ there is some audio input? I'd probably use the > rec command from the sox package for recording, and probably > something like lame for MP3 conversion. Use sox it has no trouble encoding to mp3 in real time (or flac which is my preferred recording format) and can be told to skip leading silence - I use it like this to create timestamped recordings without leading silence. NOW=`date -Iseconds | cut -c12-19` rec $NOW.flac silence 1 0.5 0.1% You could start with that and watch for the file to start growing to see when sound starts. But sox is cleverer than that - viz this extract from man sox: rec -r 44100 -b 16 -e signed-integer -p \ silence 1 0.50 0.1% 1 10:00 0.1% | \ sox -p song.ogg silence 1 0.50 0.1% 1 2.0 0.1% : \ newfile : restart records a stream of audio such as LP/cassette and splits in to multiple audio files at points with 2 seconds of silence. Also, it does not start recording until it detects audio is playing and stops after it sees 10 minutes of silence. I suspect you can torture sox into doing pretty much what you want but you'll have to wrap your head round the silence and newfile options :) -- Steve O'Hara-Smith