220 26175 <1e023fde-b641-4957-8420-d6426c0e6ebd@isocpp.org> article Path: news.gmane.org!not-for-mail From: mlal1811@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Any interest to adding audio support to the std library? Date: Sat, 4 Jun 2016 07:08:07 -0700 (PDT) Lines: 125 Approved: news@gmane.org Message-ID: <1e023fde-b641-4957-8420-d6426c0e6ebd@isocpp.org> References: <5751B06A.4080501@mail1.stofanet.dk> <5290948.va25uYNizX@tjmaciei-mobl1> <1580229.cHEgQxCuA1@tjmaciei-mobl1> <62b7649a-5de5-4330-9bac-708375d36e2c@isocpp.org> <4cfc7939-1ebf-415f-8ef4-d51e7cdadef5@isocpp.org> <239cb9ab-c5d5-4ce5-b876-b5220cc1e116@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1224_1162882466.1465049287909" X-Trace: ger.gmane.org 1465049294 2791 80.91.229.3 (4 Jun 2016 14:08:14 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 4 Jun 2016 14:08:14 +0000 (UTC) Cc: alexander.zywicki@gmail.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDG2JSELZQORBSOBZO5AKGQEWJUSGLI@isocpp.org Sat Jun 04 16:08:13 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qg0-f71.google.com ([209.85.192.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1b9CFH-0004ZW-0H for gclcip-std-proposals@m.gmane.org; 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Sat, 04 Jun 2016 07:08:10 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.73.204 with SMTP id e73ls239002itd.10.canary; Sat, 04 Jun 2016 07:08:08 -0700 (PDT) X-Received: by 10.36.17.140 with SMTP id 134mr10452itf.6.1465049288946; Sat, 04 Jun 2016 07:08:08 -0700 (PDT) In-Reply-To: <239cb9ab-c5d5-4ce5-b876-b5220cc1e116@isocpp.org> X-Original-Sender: mlal1811@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:26175 Archived-At: ------=_Part_1224_1162882466.1465049287909 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Saturday, June 4, 2016 at 1:28:01 AM UTC-5, Ron wrote: > Some thoughts... >=20 >=20 > 'N' should be runtime for channels in a frame and for a frame buffer. =C2= =A0The buffer size might be negotiable with the device. >=20 >=20 > I like a lot of that code in the original post, but I don't like the comp= arison to iostreams. =C2=A0Its really the '>>' operator that I don't like. = =C2=A0When you copy into your frame buffer, an '=3D' operator should be use= d since anyone that sees an '=3D' operator knows its a copy. =C2=A0But real= ly, you shouldn't need to move data around so much. =C2=A0If you stream fro= m input to 'buff', then process and then move from 'buff' to output then yo= u are moving a lot of data unnecessarily. >=20 >=20 > I think what should happen is this; The process chain is triggered when t= he output signals it is ready for data by calling the first linked process.= =C2=A0Starting at the output, each process kernel calls the previous until= it reaches the input where the input device/file/etc copies the data to th= e chains frame buffer. =C2=A0Each process then operates on that single buff= er in turn until finally returning to the output, thus altering the buffer = instead of moving data from place to place. =C2=A0I like to think of the pr= ocessing chain as starting from the output or destination. =C2=A0When the o= utput is ready for data it calls to a linked process for information, it ca= lls to the next link and so on until data begins to get processed. =C2=A0So= a bottom up approach, where the input doesn't officially start until the o= utput is ready. =C2=A0I know it is opposite of the way audio really flows t= hrough a system but it makes things easier then moving data like a bucket b= rigade. =C2=A0It can also allow easier parallel processing when there are m= ultiple branches on a node. =C2=A0So if you think of an audio mixer, where = there are many inputs and a single output, the output calls to many channel= s/nodes at once so they can all be processed in parallel and mixed together= after each of the processes end. >=20 >=20 >=20 > Also, I'm not sure the word 'format' should be used to refer to files. = =C2=A0I know people like to say "file format" but then, what format is the = audio data in that is in the file format? =C2=A0Its just confusing, so I th= ink 'container' is a better word for files. =C2=A0Then that leaves the word= format open for use as a way of describing the data format of an audio fra= me buffer. =C2=A0So an audio_format class would contain information on samp= le rate, channels, interleaving, channel routing and other information and = a container class would deal with files. >=20 >=20 > I personally would rather have all audio with greater than 2 or 3 channel= s processed in Ambisonic-B format and then have the audio driver figure out= how to extract the channels for each speaker, but I know this won't fly wi= th everyone so we would need a class for channel routing information as wel= l. >=20 >=20 > All I can think of at the moment.. >=20 >=20 >=20 >=20 >=20 >=20 > On Friday, June 3, 2016 at 9:08:45 PM UTC-7, alexande...@gmail.com wrote: > I agree, how do you feel about the concept i proposed in my original abou= t having std audio stream classes similar to std::fstream. The std::astream= /iastream/oastream would represent the default audio device on the system a= s determined by some method of polling the system. The user could either ch= oose to use them as is or manually select a different device? >=20 > On Friday, June 3, 2016 at 10:51:12 PM UTC-5, Ron wrote: > Well, it needs to start somewhere.=C2=A0 I think having basic buffers usi= ng std::array or plain old arrays might do for now and get some basic audio= recording and playback into C++.=C2=A0 It should be as simple as possible = to get to the interfaces on the machine and make them work.=C2=A0 The data = processing can build onto it with more complex primitives, templates and cl= asses.=C2=A0 This way there is at least something semi-usable with code we = have today while the rest of the building blocks are being worked on.=C2=A0= Just a thought though. For the most part I agree with you, I think that using the << operator in t= he callback would be confusing and ahold be replaced with =3D to be more cl= ear, and that the callback parameters should be changed to be of type frame= _buffer to keeps things simple. But I think that using the << operator for = routing purposes still may be useful. Consider the situation where you woul= d like to have multiple types of inputs/outputs or connect to multiple devi= ces and need to specify which ones you are routing to and from. My intent t= here was to provide an interface that allowed you to specify that your prog= ram would take input from 0-N selected inputs and 0-N selected outputs if d= esired.=20 I think using a pull model for determining order of operations could work i= n most cases but it would be more complex if you desired a multi out situat= ion. The model that worked best in theory for me in that situation was to t= reat the signal flow as a graph and have each node in the graph keep track = of its completion for the buffer period, the outputs would ask their depend= ent nodes if they are done and if so take the result, in turn those nodes w= ould ask their dependent nodes or inputs about completion until the graph r= eaches all input or non dependent nodes. A friend of mine likened this to A= * path finding without weighting certain paths. Each node waits on its depe= ndents, which eventually will be a device input or a file. This all of cour= se assumes support of a graph model that allows for dynamic connection of I= /o, which I find to be desirable.=20 Do you think that multiple io should be supported?=20 Do you think that there needs to be some way of routing between the devices= and your program? --=20 You received this message because you are subscribed to the Google Groups "= ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/1e023fde-b641-4957-8420-d6426c0e6ebd%40isocpp.or= g. ------=_Part_1224_1162882466.1465049287909-- .