Linux-audio-dev August 2004

linux-audio-dev@lists.linuxaudio.org

86 participants
67 discussions

[linux-audio-dev] S/PDIF, PCM, and AC-3 Capturing

by Braman, Paul

It may be that this topic is already covered somewhere, but after much searching over the past few days I have been unable to come up with a comprehensive guide to what I am attempting to do. (Note that I've never written something like this before but know enough about Linux and how things work that I would probably understand a higher-level discussion on the topic...maybe. [grins]) I am attempting to write a program that will capture and record digital audio (in the form of PCM/AC-3 over S/PDIF). What I *do* with that data is a secondary issue and not something I want to get into now. The input to the "system" is a USB digital audio capture device. (I currently have an Edirol UA-1D (http://www.edirol.com/products/info/ua1d.html) and Creative Labs MP3+ (http://www.creative.com/products/product.asp?prodid=154) at my disposal.) What I'm not sure of is what I am looking for (or what I should expect to find). The S/PDIF stream that will be coming into the device may have PCM or AC-3. My basic assumptions on this topic are that I will have to find some /dev entry to open and read from to do the capturing itself, but from everything I've read so far it doesn't look like the standard /dev/audio or /dev/dsp devices would suffice. So, there you have it. I'm looking for some pointers to get the ball rolling and I'm positive I'll be able to pick it up from there...it's always the first few steps that are daunting. The kind of questions I am asking are: 1) With the USB audio device plugged in, what device would I need to open to read the raw digital data? 2) Is there an API already available for reading this information? (I've looked at OSS, but haven't gotten much into ALSA yet.) 3) Assuming I can get at *a* bitstream, what will it contain? Will it be the S/PDIF stream from which I will need to extract PCM/AC-3, or will it be the raw PCM/AC-3 itself? Thanks. Paul Braman Paul dot Braman at NielsenMedia dot com 813-366-5053

20 years, 3 months

[linux-audio-dev] Firewire Breakout-Boxes

by Daniel Wagner

Hi, I'm pleased to announce a project which eventually should support several Firewire-based breakout-boxes. Following boxes would be supported: - ESI QuataFire 610 - M-Audio Firewire Audiophile - M-Audio Firewire 410 - M-Audio Firewire 1814 - Terratec Aureon 7.1 FireWire - Edirol FA-101 Each of those boxes is using the same chip produced by the company I'm working for. I got green lights from my boss to do write a driver for linux. Of course, this is not a very simple task. Most information which is needed for writing a driver is available as Standards. Well, some information is not available as standards... If someone is interested to participate in this undertaking I would be very glad, because it is a large task and I have only little resource left for this project. So it would take rather long to finish it and I'm sure some of the LAD guys are eager to use something different than an USB based breakout box. Any serious hacker who signs a NDA gets access to all information and will also have for access to hardware (test boards). If s/he is not signing (for some reason) only the public available Standards most be enough. Access to hardware can still be arranged (hopefully). Anyway I have already started to code something but it is still at very very very early stage and not good for anything. Therefore I haven't loaded it up somewhere. cheers, daniel

20 years, 4 months

[linux-audio-dev] miniDV audio format

by Eric Dantan Rzewnicki

1)Does anyone know what format digital audio is stored in for miniDVs? I know the audio can be 12 or 16 bit and I know that (at least for the tapes I have) SP is about 60 minutes and LP is about 90 minutes. So, I figure the sample rates are probably something like 48kHz for SP and 32KHz for LP, but I haven't found a definitive reference, yet. I ask because I've had a canon zr60 miniDV camcorder for about a year and have recently started using it to collect sounds. For now I'm recording from the analog output of the camcorder into my delta66. Obviously, this is less than ideal, but far superior to the handheld voice recorder analog cassette tape solution I've been using for the past 8 years. :-] 2)I've briefly glanced over the web page for kino: http://kino.schirmacher.de/article/static/2 It appears kino will handle recording the video from a ieee1394 connection and also includes a tool for stripping audio out of the video to a wav file. Anyone here have any experience to share in using kino, or any other package, to do something like this? 3)Does it matter what ieee1394 interface I get, or are they all basically the same as long as there's kernel support for them? Thanks in advance, Eric Rz. PS appologies if this has been discussed recently. I've been away on vacation and haven't had time to follow the lists closely for 3-4 weeks. -edrz

20 years, 4 months

[linux-audio-dev] Re: [linux-audio-user] Regarding NoteEdit, Finale, and rumor

by Dave Phillips

Hi Matt: Thanks for the further clarification. I suppose that the simple fact is that the Linuxadio community simply doesn't "number up" enough for Coda to consider us any sort of market. Same old story. Yawn, heavy sigh... But the truth is that I'm not really interested in Finale, I'm interested in libre software, and my concern is for the continued development of NE. It would be nice if someone would step up and take the reins, and as I said earlier, that is my hope now for NE. Would I buy Finale for Linux ? Probably, at least to see what the hubbub is all about. Ditto for Cubase or really any other music app that would run under my favorite OS, but I would want to make an equal or larger contribution to the developers of functionally equivalent libre software. My two drachmas, of course... Best, dp Polashek, Matthew wrote: >Hi! >I met with the president nd founder of Coda, (Now Makemusic!) a few months >ago at work(Silver Burdett Ginn) and I asked him if they were going to >publish a Linux version of Finale now that they have completed an OSX >version. He said that his programming and marketing staff had brought the >idea up but that they were not going to make a Linux version at this time. > >FYI. > >Matt. > >

20 years, 4 months

[linux-audio-dev] Hello - FYI - intro

by mark＠kfm.co.za

Hi my name is Mark and I have been a silent member for two years - having very little experience with the in's and out's of Linux. For many years I have blindly believed that Linux is the way to go - more because of the concept of Open Source which ties in exactly with my own belief structure. I have supported linux for years in the form of mail servers but my own knowing has been lacking. Recently ( 2 months ago ) I reinstalled all my systems without the comfort of partitioned disks and windows as a safety net. To date I have re-installed my system close to ten times. I am only now realizing that I may have a hdd problem or hardware in general - although no errors are evident. I have a life long ambition to make sound - to generate ecstacy - to move energy - to drown people - to open portals of thought and recreation to fly - to dream - to enlight. In reality I am stuck with my finger on the reset button. My setup - P4 - 256 ram - Slackware 10.0 - linux 2.6.7 - My problem as an end user - is limitless - while the discussion group handles issues like left or right up or down this or that it seems as if you all live in Utopia with perfect systems. My problems as a beginner are endless. My linux thought is that the main difference between linux and windows is that under windows everything is packaged i.e. that one installation will actually get that desired product to work - while under linux a lot more time is spent on finding the correct patches mixes matches reading than end time using/producing. Obviously linux has flexibility power stability way beyond the confines of windows or mac but it is the tieing up of those 'loose ends' which make it easier for a new user to get going that make the ultimate difference. While windows users have licence issues some linux users have other. It matters little to me if one program does something in one way as opposed to a different way in a different program - i.e. each program is unique unto itself and should be learnt seperately. My problem in this area has been to get them to work together or through each other with results. I return to my silent world of learning and eventually achieving in linux but that's my two cents. I believe in Linux and all that it stands for and wish no insult to any. Thank you for this moment. bye Mark Mark McBride Cell 08 4414 6809 Tel.: +27 21 462 0044 Fax: +27 21 465 0277 Bitwise Computer systems EMail : tech-support(a)bitwise.co.za EMail : sales(a)bitwise.co.za ____________________________________________________________________________ The information in this e-mail is confidential and is intended solely for the addressee. Access to this e-mail by anyone else is unauthorised. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted in reliance on this, is prohibited and may be unlawful. Whilst all reasonable steps are taken to ensure the accuracy and integrity of information and data, and to preserve the confidentiality thereof, no liability or responsibility whatsoever is accepted if information or data is corrupted or does not reach its intended destination. KFM Radio (Pty) Ltd. will not accept responsibility for unauthorised use, be it public or private, to express opinion, promote or demote individuals or groups.

20 years, 4 months

[linux-audio-dev] Re: [linux-audio-user] Setting up linux computer

by ChristianH

Hi all, I'm in a similar situation. Within a couple of weeks I'll be buying a new PC which (besides still running Windows) should be, say, at least Linux friendly. Since in this case I'm not tied to given legacy hardware, I'd rather put in some components that are particularly suitable for Linux. >From what I heard, culprits can be - audio card - graphics card (hi resolution, 1280+, no 3D game capability needed) - and I assume MIDI interface as well (6 to 8 ports in+out) Are there cards with rather good Linux driver support? Are there cards better to avoid in Linux world, due to their poor driver status? Is there a Linux hardware FAQ site somewhere, with some recommendations? Until now I've been using an Emagic AW8 audio card, which perfectly fits my needs (don't really need 24/96k or oodles of audio ports). For Windows I was considering an Emagic AMT8 or Unitor8 interface, but I don't remember seeing any Linux drivers on their site (well, they may call'em OS X drivers... ;-) Another component may be somewhat outside this list's topics, I'm thinking of adding a video MPEG input/encoder card as well - maybe somebody can give me any pointers on that...? regards Chris On Tue, 24 Aug 2004 04:16:39 +0000 Thomas Pickett wrote: > >On Sunday 22 August 2004 04:37 pm, Frank Barknecht wrote: > > > Hallo, > > > > > > There are many more (pci cards), a very popular one being the RME card. > > > Can anyone suggest a good RME Card? I have looked at their website but was > wondering if anyone had personal preference. I preferably would like a > sound card with mutilple in/outs, mic in/outs, midi, spdif. > > Once again I appreciate all the feedback. As for distros, I'm leaning > towards debian, but I will do some more research. > > Thanks, > Thomas

20 years, 4 months

[linux-audio-dev] Re: [linux-audio-user] Linux Audio Human Interface Guidelines, 0.01 (was Re: mouse wheel behavior and RFC: human interface, guidelines)

by Lee Revell

On Wed, 2004-08-25 at 17:52, Paul Winkler wrote: > On Wed, Aug 25, 2004 at 06:02:44AM +0000, philicorda wrote: > > Paul Winkler wrote: > > > > "I could swear I remember seeing an old tube compressor that > > had a gain reduction meter with "more" to the right, so it > > moved in opposition to the corresponding VU meter. > > No idea what model it was, and this was about 6 years ago > > so I could be mistaken. > > > > I wonder how consistent this is in the world of hardware? > > maybe I'll pop a question on rec.audio.pro." > > btw, i had myself turned around again :-) > If the gain reduction meter is moving in opposition the VU meter, > then "more" gain reduction is to the left, not right. > > > I built a tube compressor like that, an Altec436c. > > The 'gain reduction' meter measures the bias current of the vari-mu > > valve, which is reduced when gain reduction is required. > > The meter goes from right to left. (Any other way would require more > > circuitry, so I think it may just be a lucky accident.) > > ah, that's an interesting point. > > > Talking of meters, don't some phase meters often go left *and* right > > from a centre point to show averaged phase difference between the channels? > > think so. >From the wide variety of responses describing all types of meters, it seems that the HIG should steer clear of this topic and leave it the developer's responsibility to make your meters intuitive. HIGs are not about restricting the range of functionality you can implement, they are just there to prevent needless usability regressions (aka usability bugs). An example of a usability regression would be when a user expects the leftmost menu to be 'File' and the 'Save' option to be found in it, but then encounter some app which puts the 'Save' option on the 'Edit' menu. Since neither way is intrinsically better, the former is the correct choice, because that is the way users expect it to work. Is there any known broken meter behavior that we should prohibit? So far I have not seen an example in this thread. Lee

20 years, 4 months

[linux-audio-dev] a new patent to worry about

by Paul Davis

http://news.harmony-central.com/Newp/2004/L3.html

20 years, 4 months

Re: [linux-audio-dev] Hello - FYI - intro

by Taybin Rutkin

Just out of curiousity, what optimizations did he suggest and which ones were a good idea? Taybin -----Original Message----- From: Erik de Castro Lopo <erikd-lad(a)mega-nerd.com> Sent: Aug 25, 2004 3:58 AM To: The Linux Audio Developers' Mailing List <linux-audio-dev(a)music.columbia.edu> Subject: Re: [linux-audio-dev] Hello - FYI - intro On Tue, 24 Aug 2004 19:56:27 -0400 Paul Winkler <pw_lists(a)slinkp.com> wrote: > On Tue, Aug 24, 2004 at 06:35:12PM -0400, John Check wrote: > > > > It's completely dwarfed by compile time. > > > > > > > Are you sure you wanted to say that ;) > > Yes. First rule of optimization: don't optimize something that's > statistically irrelevant. <vent=11/10> I wish that attitude was more prevalent in the ricer community. I've been getting emails from a Gentoo ricer suggesting a whole bunch of "optimisations" for libsndfile. A small number of these were valid, but the vast majority were not measurably faster as measured by the benchmark program shipped with libsndfile. </vent> Erik -- +-----------------------------------------------------------+ Erik de Castro Lopo nospam(a)mega-nerd.com (Yes it's valid) +-----------------------------------------------------------+ "The X-files is too optimistic. The truth is not out there." -- Anthony Ord

20 years, 4 months

[linux-audio-dev] mouse wheel behavior and RFC: human interface guidelines

by Lee Revell

I just installed jack-rack and find the mouse wheel behavior a bit odd. The sliders are horizontal, and turning the wheel 'up' (away from you) decreases the slider value, and vice versa. This seems backwards to me. What does everyone else think? This is one of those things that will *have* to work the same way in every app, otherwise it's maddening for users, so we had better agree on it now. Alternatively, there has to be one place where this behavior can be set for all apps. What is not acceptable is for 50% to do it one way and 50% the other. What is really needed is a set of human interface guidelines for Linux audio apps. Better to do this now, while much of the code is not mature, than later, and have a bunch of different apps which work, except that the widgets work completely different from one app to another for no good reason other than that person A felt like doing it like this and person B like that. You can talk about freedom all you want but the users do not care about this kind of thing, it just looks like the left hand is not talking to the right. Professional users (rightfully) demand a consistent interface, unless there is a good reason (extra functionality) not to provide one. I would like to start putting these guidelines together. A good place to start is to document the behavior of the most popular and mature existing apps. Any suggestions are welcome. Lee

20 years, 4 months

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Linux-audio-dev August 2004