Re: [Alsa-user] best card for bitperfect SPDIF I/O?with?external clock sync ?
On Mon, 26 Nov 2007, Sergei Steshenko wrote: On Mon, 26 Nov 2007 18:19:24 +0100 Benoit Rouits [EMAIL PROTECTED] wrote: Le dimanche 25 novembre 2007 à 18:26 +0300, Vladimir Mosgalin a écrit : That's the main reason why I asked - I heard that people can hear 22khz or about that when they are young, than listening gets worse and they don't hear very high frequencies anymore - and since I consider myself still young ;), I was kind of disappointed by the fact that I can't hear not only 22khz, but even 20khz, and when I discovered that I can't hear even 18khz, I was kind if scared - is my hearing going down due to headphone usage? Thanks for clarifying this issue. Theorically, A 44100 sampled audio CD can reproduce a triangle signal at 22050 Hz. No, it can't. Sure it can. The difference between a triangle wave and a square wave a 22000 is harmonics whose frequency is far higher than 22050. Ie, the harmonics are irrelevant. Thus a triangle, a square, a sine, a sawtooth are all the same. One could say that the triangle is closer since it has lower amplitude harmonics than most of the others. Draw timing diagrams with different relative phases of the signal and sampling frequencies. Your output will be 22050 Hz 50% duty cycle square wave whose amplitude (and polarity/phase) depend on the above relative phase.- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O?with?external clock sync ?
On Mon, 26 Nov 2007 10:52:17 -0800 (PST) Bill Unruh [EMAIL PROTECTED] wrote: On Mon, 26 Nov 2007, Sergei Steshenko wrote: On Mon, 26 Nov 2007 18:19:24 +0100 Benoit Rouits [EMAIL PROTECTED] wrote: Le dimanche 25 novembre 2007 à 18:26 +0300, Vladimir Mosgalin a écrit : That's the main reason why I asked - I heard that people can hear 22khz or about that when they are young, than listening gets worse and they don't hear very high frequencies anymore - and since I consider myself still young ;), I was kind of disappointed by the fact that I can't hear not only 22khz, but even 20khz, and when I discovered that I can't hear even 18khz, I was kind if scared - is my hearing going down due to headphone usage? Thanks for clarifying this issue. Theorically, A 44100 sampled audio CD can reproduce a triangle signal at 22050 Hz. No, it can't. Sure it can. The difference between a triangle wave and a square wave a 22000 is harmonics whose frequency is far higher than 22050. Ie, the harmonics are irrelevant. Thus a triangle, a square, a sine, a sawtooth are all the same. One could say that the triangle is closer since it has lower amplitude harmonics than most of the others. Draw timing diagrams with different relative phases of the signal and sampling frequencies. Your output will be 22050 Hz 50% duty cycle square wave whose amplitude (and polarity/phase) depend on the above relative phase. I'm saying it again - just draw the suggested timing diagram. It will be a very good illustration of aliasing. Furthermore, if the phase is such that sampling occurs at every zero crossing, the sampled signal will be 0/zero/null/zilch - you name it. The point/problem that the original poster suggested input signals with fundamental being the exact Nyquist frequency. --Sergei. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O?with?external clock sync ?
Hi Bill Unruh! On 2007.11.24 at 10:11:16 -0800, Bill Unruh wrote next: Thank you for all your responses! That is quite normal It is in fact good hearing (although many kids can hear up to 22-25 kHz). And it will get worse, especially if you like That's the main reason why I asked - I heard that people can hear 22khz or about that when they are young, than listening gets worse and they don't hear very high frequencies anymore - and since I consider myself still young ;), I was kind of disappointed by the fact that I can't hear not only 22khz, but even 20khz, and when I discovered that I can't hear even 18khz, I was kind if scared - is my hearing going down due to headphone usage? Thanks for clarifying this issue. listening to music on your headphones. Almost all headphone users have their headphones cranked up WAY to loud, and that destroys the nerve cells in the ear. A bus, going up a hill, has sound levels inside of the order Hey hey, I know what's good for me ;) I only listen to headphones in quiet places nowadays and at comfortable volume levels. of 80dB and in order to hear the music people crank up their heaphones to 90 or 100 dB. After only a few years of that your threshold will be down to Actually there are solutions, like good in-ear noise isolation headphones, for example ER6 and ER4 are pretty good (though expensive) - http://www.etymotic.com/ephp/er6.aspx, with background isolation over -30dB. Actually I thought about using such thing when I'm outside, the only problem is that I think it may be too dangerous to walk in the city and cross the streets with such isolation. There are also active noise-cancelling headphones, though I'm not too fond of them. 14kHz then 8kHz then 3kHz. With any luck you will effectively be deaf by the time you are 40, and can join the ranks of almost all rock musicians. It can't be that scary. You mean that all people who are listening to headphones in bus are going to end like this? We'll become a deaf nation then. Nature must have thought of something to prevent this from happening. Or, science will help ;) -- Vladimir - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O?with?external clock sync ?
On Sun, 25 Nov 2007, Vladimir Mosgalin wrote: Hi Bill Unruh! On 2007.11.24 at 10:11:16 -0800, Bill Unruh wrote next: Thank you for all your responses! That is quite normal It is in fact good hearing (although many kids can hear up to 22-25 kHz). And it will get worse, especially if you like That's the main reason why I asked - I heard that people can hear 22khz or about that when they are young, than listening gets worse and they don't hear very high frequencies anymore - and since I consider myself still young ;), I was kind of disappointed by the fact that I can't hear not only 22khz, but even 20khz, and when I discovered that I can't hear even 18khz, I was kind if scared - is my hearing going down due to headphone usage? Thanks for clarifying this issue. listening to music on your headphones. Almost all headphone users have their headphones cranked up WAY to loud, and that destroys the nerve cells in the ear. A bus, going up a hill, has sound levels inside of the order Hey hey, I know what's good for me ;) I only listen to headphones in quiet places nowadays and at comfortable volume levels. Hey, most people have no idea what the volume levels are. If your headphones are giving you pain they are probably at 120dB. Most people will regard 80-90dB as comfortable Your ears are incredibly adaptable and will get used to almost everything. Ie, I have zero confidence that because you call it comfortable it is not loud enough to harm your ears. of 80dB and in order to hear the music people crank up their heaphones to 90 or 100 dB. After only a few years of that your threshold will be down to Actually there are solutions, like good in-ear noise isolation headphones, for example ER6 and ER4 are pretty good (though expensive) - http://www.etymotic.com/ephp/er6.aspx, with background isolation over -30dB. Actually I thought about using such thing when I'm outside, the only problem is that I think it may be too dangerous to walk in the city and cross the streets with such isolation. There are also active noise-cancelling headphones, though I'm not too fond of them. Yes, that solves the background noise problem. It does not solve the I want to be immersed in the music problem. y 14kHz then 8kHz then 3kHz. With any luck you will effectively be deaf by the time you are 40, and can join the ranks of almost all rock musicians. It can't be that scary. You mean that all people who are listening to headphones in bus are going to end like this? We'll become a deaf nation then. Yup. Nature must have thought of something to prevent this from happening. Or, science will help ;) Nope. Nature is very quiet. Evidence is that people who actually live in nature do not loose their hearing as they get older-- they keep that ability to hear 20KHz into their 80s. You think cities are nature? And science cannot regrow hair cells. There is an easy way to prevent this from happening-- keep the volume low. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O?with?external clock sync ?
Hi Gene Heskett! On 2007.11.23 at 11:56:56 -0500, Gene Heskett wrote next: Anyway, in analog mode, are you sure there is no option to switch off bandwidth filter? No one in their right mind would want to do that as the aliasing would drive you up a wall. The other delay distortions the filter might give are 100's of times more tolerable to listen to. Er.. I meant in 96khz mode. Or in 48khz. I understood original letter as if the card has that bandwidth limitation on any sampling frequency, and this is a problem. Of course at 44.1khz D-A conversion it's desired to have something like that. Not that it matters in digital mode, since it's up to DAC filters. PS a bit of OT: I'm 24, and I barely hear 18khz (in headphones), unless it's VERY loud - I can hear only up to 17500-17800 clearly at average volume level. Is there something wrong with my ears or it should be like this? -- Vladimir - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O?with?external clock sync ?
On Sat, 24 Nov 2007 13:49:30 +0300 Vladimir Mosgalin [EMAIL PROTECTED] wrote: PS a bit of OT: I'm 24, and I barely hear 18khz (in headphones), unless it's VERY loud - I can hear only up to 17500-17800 clearly at average volume level. Is there something wrong with my ears or it should be like this? No, you're OK. When I was your age 18kHz was my limit too. The point is signal envelopes and the fact that for a minimum filter phase response is unambiguously calculated from from amplitude one. I.e. audio bandwidth requirements were made to first of all not to distort envelopes - IMHO. --Sergei. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O?with?external clock sync ?
On 24-11-07 11:49, Vladimir Mosgalin wrote: PS a bit of OT: I'm 24, and I barely hear 18khz (in headphones), unless it's VERY loud - I can hear only up to 17500-17800 clearly at average volume level. Is there something wrong with my ears or it should be like this? You're perfectly fine. It all depends on average and very in the above but if you hear 17+ kHz at... average-average levels you could call this fine hearing. Nice reference: Ahmed, Dennis, Badran, Ismail, Ballal, Ashoor, Jerwood: High-frequency (10-18 kHz) hearing thresholds: reliability and effects of age and occupational noise exposure http://occmed.oxfordjournals.org/cgi/reprint/51/4/245.pdf If you look at table 1 there, you see that for your age group, 100 dBSPL (*) is to be expected for 18 kHz which is indeed VERY loud. The 20 kHz upper bound that is normally used is just that, an upper bound and if we're talking about young ears in those ranges, we're talking baby-young. (*) http://en.wikipedia.org/wiki/Sound_pressure_level Rene. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O?with?external clock sync ?
On Saturday 24 November 2007, Vladimir Mosgalin wrote: Hi Gene Heskett! On 2007.11.23 at 11:56:56 -0500, Gene Heskett wrote next: Anyway, in analog mode, are you sure there is no option to switch off bandwidth filter? No one in their right mind would want to do that as the aliasing would drive you up a wall. The other delay distortions the filter might give are 100's of times more tolerable to listen to. Er.. I meant in 96khz mode. Or in 48khz. I understood original letter as if the card has that bandwidth limitation on any sampling frequency, and this is a problem. Of course at 44.1khz D-A conversion it's desired to have something like that. Not that it matters in digital mode, since it's up to DAC filters. No it isn't, once the aliasing is in the digital domain, it cannot be filtered away because its now part of the 'active bandwidth', so the filters really do need to be 'brick wall', at slightly less than 1/2 the sampling frequency. PS a bit of OT: I'm 24, and I barely hear 18khz (in headphones), unless it's VERY loud - I can hear only up to 17500-17800 clearly at average volume level. Is there something wrong with my ears or it should be like this? That's probably somewhere near normal and might depend slightly on how much wax buildup is in the ear canals, and on the headphones themselves, I see a lot of boxes on the shelves proclaiming 30hz-18khz. I'd be willing to bet that you can walk into some business with an ultrasonic doppler based burglar alarm running, and feel it. Those things can put several watts into the air at around 40 kilohertz. The false alarm rates with those were pretty high, specially if they could see a big picture window, which flexes in the wind enough to trigger the alarm. I don't think they are as popular now as back in the early 80's though, for that reason. I don't think I'd worry too much about it just yet. I'm not wearing any aids and I'm getting along fairly well yet. -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) Mal: So Shepard says to a Companion, Well, a good goat will do that. --Episode #5, Safe - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
Paolo Saggese wrote: On Thursday 22 November 2007 15:25, you wrote: This is a valid wish, isn't it? And at least the M-Audio Audiphile cards can sync themselves to the S/PDIF In clock. They can, but the word clock is used only as a sample clock. It will not reduce the amount of jitter of the card's S/PDIF output. that's not a concern! Let' try to explain it better: it's all about avoiding the use of the SPDIF reconstructed clock altogether (on the DAC side). The S/PDIF standard specifies that the clock must be reconstructed from the signal itself. If I can slave the SPDIF clock coming into the external DAC to the same DAC local clock, I can simply ignore the incoming SPDIF clock and just use the local one without any need for reclocking, PLLs, etc! Yes, _if_ you can. http://www.audiocraftersguild.com/AandE/npt.on.jitter2.htm says: | A few companies which make both transports and external DACs have | implemented schemes in which the S/PDIF signal is supplemented with a | second line carrying the master clock back from the external DAC to | the transport. In this way the DAC's crystal becomes the master rather | than the transport and the problems of recovering a spectrally pure | clock are eliminated. No standards for this type of implementation | exist. In reference #4 Dr. Hawksford calls for the clock signal to be | transmitted on a second S/PDIF line, I know of no actual product which | implements this scheme. Sony (in one product) and Arcam send the | actual clock, Linn argues this leads to RFI problems and so they send | a DC servo voltage which controls a VCOX in the transport. So it seems you wouldn't be able to find a sound card that does what you want. If all your audio data comes from the PC anyway, you might want to drop S/PDIF and use a sound card with a break-out box. The I2S bus used to control the DACs in those devices has a separate master clock line. Regards, Clemens - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
Hi Darrell Bellerive! On 2007.11.22 at 17:54:19 -0800, Darrell Bellerive wrote next: I have never been happy with this card. While it works okay for playing basic sound, getting it to do anything more sophisticated is pure black magic. For example, I have never gotten full duplex to work. Well now, when pulseaudio era came, hopefully it's not true anymore. Also while the Audiophile 24/96 does sample at 96 KHz, the audio bandwidth of the card is limited to 22 Hz to 22 KHz +/- 0.4 dB. How does that matter when all is needed is digital output? Anyway, in analog mode, are you sure there is no option to switch off bandwidth filter? -- Vladimir - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
Paolo Saggese wrote: Of course I plan to use the PC only to provide a bitperfect (exact copy of the original media, normally CD) digital stream to an external DAC. As you probably know better than me, the one major known problem when you strive for the highest possible quality in digital audio reproduction is jitter... and the best (if not only) way to really minimize it is to use a good, clean and stable clock close to the DAC chip, slaving everything else to that one. Thus, what I would need to do would be to slave the sound card SPDIF output clock to the external DAC clock i.e. to make this one become the master clock for the whole digital audio stream. An SPDIF input _always_ derives its clock from its signal. Besides, the clock for the actual DAC has to be a multiple of the bit clock anyway, so there must be a PLL to derive the DAC's clock from the input signual, i.e., the amount of DAC clock jitter depends more on the PLL implementation than on the input signal quality. AFAIK, one possible way to do this is to set up a fake SPDIF output from the external DAC and connect it to an input of the sound card whose SPDIF output goes to the DAC for conversion. Of course the sound card must be able to slave (synchronize) its SPDIF output clock with the one coming from its SPDIF input. There are sound cards that have a word clock input (M-Audio Delta and others based on the ICE1712 chip), but a word clock is only used to force multiple devices to run at the exactly same frequency, i.e., to prevent their clocks from drifting apart. This clock can _not_ be used as a bit clock for digital signals. Even if it were possible, the extra SPDIF connection would introduce additional jitter, thus the SPDIF signal received by the DAC would have more jitter, compared to the case where the sound card uses its own clock for the SPDIF signal. In other words, the sound card's internal clock is of higher quality than any clock that has to be received from an external device. Thus, I would need a sound card which must be: * cabable of bitperfect (pass through) operation at CD standard 16bit/44.1KHz (as well as, possibly, also at higher resolutions and sample rates such as 16/48, 24/48, 24/96 and 24/192). Any cheap CMI8738-based card can do 16 or 24 bits at 44.1 or 48 kHz. Cards based on the CMI8768 chip (and some later 8738 models) or based on the ICE1712 chip support 24/96. Regards, Clemens - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On 21-11-07 20:33, Paolo Saggese wrote: Thus, I would need a sound card which must be: * cabable of bitperfect (pass through) operation at CD standard 16bit/44.1KHz (as well as, possibly, also at higher resolutions and sample rates such as 16/48, 24/48, 24/96 and 24/192). 16/44.1 is basic enough that any card will be able to operate its S/PDIF output at it. Traditionally, together with 16/32 and 16/48, and probably 20-bits instead of 16 possible. Basic S/PDIF is limited to those 20-bits with 24-bit as only an option in the standard but these days any card should do 24-bit fine. * capable of slaving its SPDIF output clock to an external one, such as the one reconstructed from its SPDIF input. I suppose your external DAC has no actual WordClock (BNC connection) output? If it does, you have a range of professional products available (and semipro in for example the TerraTec EWS 88 D/MT coupled with a TerraTec ClockWork module). I know the M-Audio Audiophile 24/96 and Audiophile 192 can sync the master clock with their S/PDIF in and both are great cards, also analogue, and not expensive. The 24/96 you'll even be able to locate 2nd hand by now for +/- EUR 50 or so. Check eBay -- I see them starting at EUR 0,99 ;-) As far as I'm aware, both card function well on Linux. I have neither card myself, so ask around a bit for any possible specific trouble though. Rene. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
Rene Herman wrote: On 22-11-07 11:10, Clemens Ladisch wrote: An SPDIF input _always_ derives its clock from its signal. Besides, the clock for the actual DAC has to be a multiple of the bit clock anyway, so there must be a PLL to derive the DAC's clock from the input signual, i.e., the amount of DAC clock jitter depends more on the PLL implementation than on the input signal quality. I don't quite understand your reply. He isn't asking to sync the S/PDIF in to the signal, he's asking to sync the S/PDIFF _out_ to the S/PDIF in. Ie, to have a dummy S/PDIF connection DAC -- Card S/PDIF In that exists only to supply a clock to the card, to which Card S/PDIF Out -- DAC will then be synced. This is a valid wish, isn't it? And at least the M-Audio Audiphile cards can sync themselves to the S/PDIF In clock. They can, but the word clock is used only as a sample clock. It will not reduce the amount of jitter of the card's S/PDIF output. Regards, Clemens - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
Rene Herman wrote: On 21-11-07 20:33, Paolo Saggese wrote: Thus, I would need a sound card which must be: * cabable of bitperfect (pass through) operation at CD standard 16bit/44.1KHz (as well as, possibly, also at higher resolutions and sample rates such as 16/48, 24/48, 24/96 and 24/192). 16/44.1 is basic enough that any card will be able to operate its S/PDIF output at it. Most cards support only 48 kHz output. This is either a consequence of being a wavetable card that has to mix all data together at a common frequency, or the low-budget design of the AC'97 and HDA standards. Regards, Clemens - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On 22-11-07 15:25, Clemens Ladisch wrote: Rene Herman wrote: On 21-11-07 20:33, Paolo Saggese wrote: Thus, I would need a sound card which must be: * cabable of bitperfect (pass through) operation at CD standard 16bit/44.1KHz (as well as, possibly, also at higher resolutions and sample rates such as 16/48, 24/48, 24/96 and 24/192). 16/44.1 is basic enough that any card will be able to operate its S/PDIF output at it. Most cards support only 48 kHz output. No. Not in the semi-pro range we were talking about. You'd have a hard time finding _any_ that only do 48 kHz there. This is either a consequence of being a wavetable card that has to mix all data together at a common frequency, or the low-budget design of the AC'97 and HDA standards. Ofcourse, in the horse-shit range, you will. Rene. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
Hi everybody, first of all, I'd like to thank you all so much for the prompt and many replies I've got... Wow, they came in faster then I was able to read! :-) (there's still someone claiming that Linux has no support?! :-) On Wednesday 21 November 2007 22:19, Sergei Steshenko wrote: Extracting data digitally from CD is unrelated to soundcard. Perform web search for 'cdparanoia'. mmmh... maybe I've not been clear enough with my question. Of course I know how to extract CD data. :-) BTW, in case someone could be interested (and sorry for the off topic): [OT on] In fact, unfortunately cdparanoia is not (or perhaps no longer) good enough to do perfect DAE. Sadly I had to resort to a non-free, closed source windoze software, namely EAC (at least it works well under Linux using wine and is freeware/cardware). I guess the problems with cdparanoia may be due to the fact that most (if not all) recent CD and DVD drives use to cache audio data and that perhaps fools cdparanoia checks. AFAIK in cdparanoia CVS there is/was a patch to disable audio caching, but again AFAIK it does not work and was never included in any release. If you don't believe me, try to extract several times the same CD on different drives and compare the resulting wav files... (e.g. using shntool cmp -s). Even after disregarding the possible byte-shift which is almost always present when extracting using different drives, the extracted data may (and often will) differ. IME it depends a lot on the drives used as well as on the CD being extracted. Sometimes you may find differences even when repeating the extraction on the same drive, but IME it looks like -for a given CD- the same drive tends to repeat the same errors in the same place(s). Thus this problem is definitely easier to detect comparing extractions from different drives. I have also got differences in extracted data (using the same drive) depending on the cdparanoia extraction mode, i.e. whether extracting the whole CD at once or track by track in batch mode!! ( =:-O :| I guess this may be very drive dependent, though I usually use good (or at least so believed) drives for DAE, such as Plextor ones (for the sake of curiosity I have also tried with some cheap LGs, too). In fact I used to trust cdparanoia, and had a bad surprise when I have done this tests. :-( Luckily, I did 'em before beginning the mass-extraction of my rather large CD collection... [OT off] In fact, if you want reliable sound, first transfer data from _all_ your audio CDs to HD and then play it from there. that's exactly what I was planning to do... 8-) (actually, the final plan is to use a remote RAID storage while the local, dedicated machine should be both fanless and diskless to be completely quiet). I have never used SPDIFF myself though. well, I did... but my current SC is a cheap piece of , only allows 48KHz output (aargh, resampling required... that's bad!) and of course does not allow synchronization to any external clock in any way. Nevertheless, even in such a desperate and lo-fi setup, using ALSA it didn't sound too bad when connected to my external DAC (of course playing a CD from the dedicated transport the overall quality is in another league... but I am confident that with a proper setup I can even better the CD transport results). Ciao, Paolo. -- Skype: Paolo.Saggese http://borex.lngs.infn.it/saggese You can still escape from the GATES of hell: Use Linux! - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On 22-11-07 20:49, Sergei Steshenko wrote: Just a random thought on jitter - if you like music recorded originally before the digital era - don't bother. I.e. analog tape recorder wow and flutter ( http://en.wikipedia.org/wiki/Wow_and_flutter ) is much higher than digital jitter. And that wow and flutter is already in the now digital signal. Exactly. And us purists like our wow and flutter as original as possible! Rene. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
Just a random thought on jitter - if you like music recorded originally before the digital era - don't bother. I.e. analog tape recorder wow and flutter ( http://en.wikipedia.org/wiki/Wow_and_flutter ) is much higher than digital jitter. And that wow and flutter is already in the now digital signal. --Sergei. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On Thursday 22 November 2007 11:39, Rene Herman wrote: I suppose your external DAC has no actual WordClock (BNC connection) output? indeed, it does not. As it does not have an SPDIF output, either... but I'm a DIY guy (with an EE degree...) and can add whatever output I need or even build a new dedicated DAC for the task myself, should I prefer not to modify my valuable and expensive commercial DAC. 8-) If it does, you have a range of professional products available (and semipro in for example the TerraTec EWS 88 D/MT coupled with a TerraTec ClockWork module). interesting... BTW, what about a TerraTec PHASE 22 ? mmmh, it's not even in the Matrix... :-( I know the M-Audio Audiophile 24/96 and Audiophile 192 can sync the master clock with their S/PDIF in and both are great cards, also analogue, and not expensive. The 24/96 you'll even be able to locate 2nd hand by now for +/- EUR 50 or so. Check eBay -- I see them starting at EUR 0,99 ;-) yep, I've heard of those ones, and like 'em. Though I may probably prefer TOSlink to avoid ground loops and noise transmission... But can they do what I need using ALSA? Perhaps I'm wrong but -if I remember correctly-, I've read somewhere that their support is still only partial, and one can't do what I need on Linux. Am I wrong? (doh, I hope so! :-) Another card I have seen in the semi-pro arena which seems to be almost perfect (both RCA and TOSlink I/O, support for up to 24/192, etc.) is the ESI Juli@, http://www.esi-pro.com/viewProduct.php?pid=43 From the ALSA matrix, it looks like it's based on the same chipset of the M-Audio 192. Would this be also suitable and worth the extra money? How well is it supported by ALSA? Other options? Ciao e grazie, Paolo. -- Skype: Paolo.Saggese http://borex.lngs.infn.it/saggese You can still escape from the GATES of hell: Use Linux! - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On 22-11-07 20:38, Paolo Saggese wrote: On Thursday 22 November 2007 11:39, Rene Herman wrote: I suppose your external DAC has no actual WordClock (BNC connection) output? indeed, it does not. As it does not have an SPDIF output, either... but I'm a DIY guy (with an EE degree...) and can add whatever output I need or even build a new dedicated DAC for the task myself, should I prefer not to modify my valuable and expensive commercial DAC. 8-) It probably doesn't matter all that much. And anyways, you might need to take Clemens' reply into account which seemed to say you're basically out of luck anyway as any S/PDIF in sync is not going to help any. I dunno... If it does, you have a range of professional products available (and semipro in for example the TerraTec EWS 88 D/MT coupled with a TerraTec ClockWork module). interesting... BTW, what about a TerraTec PHASE 22 ? mmmh, it's not even in the Matrix... :-( It is supported: sound/pci/ice1712/phase.c. However, near the top: Digital receiver: CS8414-CS (not supported in this release) so it might not be the best choice. I do believe it otherwise supports the same kind of external master clock sync that the Audiophiles do. I know the M-Audio Audiophile 24/96 and Audiophile 192 can sync the master clock with their S/PDIF in and both are great cards, also analogue, and not expensive. The 24/96 you'll even be able to locate 2nd hand by now for +/- EUR 50 or so. Check eBay -- I see them starting at EUR 0,99 ;-) yep, I've heard of those ones, and like 'em. Though I may probably prefer TOSlink to avoid ground loops and noise transmission... Not too fond of TOSlink myself but on short distances and when no particular subtlety of cable is desired I guess it matters not one bit. One bit. Ha. But can they do what I need using ALSA? Perhaps I'm wrong but -if I remember correctly-, I've read somewhere that their support is still only partial, and one can't do what I need on Linux. Am I wrong? (doh, I hope so! :-) As said, I have neither card myself, so I'll not say anything definite. If I look at the driver, it seems that digital in is supported at least. Just saw you get a quality reply from Vladimir. If you're expanding into external cards, many more options. Another card I have seen in the semi-pro arena which seems to be almost perfect (both RCA and TOSlink I/O, support for up to 24/192, etc.) is the ESI Juli@, http://www.esi-pro.com/viewProduct.php?pid=43 From the ALSA matrix, it looks like it's based on the same chipset of the M-Audio 192. Would this be also suitable and worth the extra money? How well is it supported by ALSA? Sorry, no idea. Rene. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
Hi Sergei Steshenko! On 2007.11.21 at 23:24:35 +0200, Sergei Steshenko wrote next: Regarding soundcard and syncrhonization - M-Audio Revolution 7.1, and quite possibly M-Audio Revolution allow you to use external clock source. I meant M-Audio Revolution 7.1, and quite possibly M-Audio Revolution 5.1 allow you to use external clock source. In theory, yes. In practice, I wasn't able to make my M-Audio Audiophile USB get clock from external source. Well it kinda works, but at some point distortions appear, and one must force clock resync or something like that by turning card off and on. I wanted to create setup similar to this, and one of the things I learned that in order to reduce jitter, you'd want to have power as clean as possible. On-board soundchips produce lowest quality signal, pci/pcie boards have much better filtering and produce better signal, but if you want something better, you have to use card which isn't powered by PSU of your PC, and doesn't suffer from problems of its signal. So if you want best digital audio, you probably should look among external cards (usb/firewire) which aren't bus powered, and use external AC adapter. Interface doesn't matter as long as card doesn't get power from it, so choose most compatible card. I picked Audiophile USB, which supports up to 24bit/96khz (though most likely you'll use it in 24bit/48khz mode). It also supports almost any sound rate without resampling, i.e. you can drive your DAC at 44100 in bit-exact mode and get highest quality possible signal, and resampling would happen only in DAC or won't happen at all (internal upsampling mode is recommended for most modern DACs though). As about quality, all I can say is that digital output from this card sounds much better than digital output from Audigy 2 ZS (both in regular or through p16v path, presumable working in bit-exact mode in the last case). As about external clock.. Audiophile usb _supports_ syncing from spdif in, but when I tried to connecting spdif out of my DAC to spdif in on card and enabled that spdif in order to synchronize, I got just noise (or very distored signal) from spdif out on card. I could get it working when spdif out on dac was set to no signal or signal from some of the unsed inputs, at some conditions I was even able to get it working with spdif out set to output signal from spdif in to which sound card was connected, but this configuration wasn't very stable and after a few hours of usage the distortions could start again. Switching the source of spdif out when it was used as clock source for the card also could produce some very strange results. Due to strangeness of this recursive scheme (imagine signal path: card output - dac input - dac output - card input - clocks from CARD's original output are used to drive next card output?) and me not understanding how and at what point re-clockings occur, but most important: completely failing to hear any advantages of this setup comparing to simplest path, I stopped experimenting with it. Now I just enjoy music and I'm quite satisfied with it ;) -- Vladimir - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On 22-11-07 19:44, Paolo Saggese wrote: [OT on] In fact, unfortunately cdparanoia is not (or perhaps no longer) good enough to do perfect DAE. Over the course of ripping 735 CDs now to my harddrive with cdparanoia, I have found that all's well as long as cdparanoia leaves nothing but spaces in its output (the command line interface). Every time I went to the trouble of comparing I've gotten byte-identical rips in those cases. But anything else, and the next rip will most likely differ even though cdparanoia may have promised to correct something. Yes, it's probably dependent on drive. Generally Plextor drives as well. Problems are most frequent at the end of tracks for some reason. The EOT exclamation mark is quite often present... Rene. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On Wednesday 21 November 2007 23:49, Bill Unruh wrote: The clock jitter tends to be in the ppm range. This means that the frequency jitter is very low (if I believe the ppm then at the level of -120dB) which is completely inaudible. My cheap Transit card reliably gives me noise unfortunately, it's not as simple as it seems... in the real world, with real (not ideal) DACs, jitter DOES matter, much more than you can think. Even at ppm or ppb levels! Nowadays there is plenty of documentation (and discussions) on the subject. Try googling for e.g. digital audio jitter if you want to know more (though the most interesting things are closed in the JAES articles, sadly out of the reach of most people). If the digital audio folks have had a lesser simplistic approach in the first place, we would not have had to wait some 20 years before gettin' a barely acceptabe sound out of a CD... (what's worse is that, nevertheless, even now a good analogue system can still sound MUCH better than any CD: it actually takes a good SACD or DVD-A system to come close to the good old LP when it comes to the real perceived audio quality!) SPDIF is a digital output stream. Its clock is irelevant. The clock on the machine that converts that stream to analog is the important one. unfortunately, SPDIF is a synchronous interface... go figure. ;-) Ciao, Paolo. -- Skype: Paolo.Saggese http://borex.lngs.infn.it/saggese You can still escape from the GATES of hell: Use Linux! - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On Thu, 22 Nov 2007 22:00:29 +0100 Paolo Saggese [EMAIL PROTECTED] wrote: [snip] If the digital audio folks have had a lesser simplistic approach in the first place, we would not have had to wait some 20 years before gettin' a barely acceptabe sound out of a CD... [snip] In a sense, one _can not_ have acceptabe sound out of a CD. That's because of (44100 / 2) is very close to 20kHz, and antialiasing LPF has insanely steep slope, causing huge phase distortions, thus severely distorting signal envelopes and creating preechos. With 48kHz the problem is much less severe, and that's why professional equipment uses at least 48kHz sample rate. Think of analog era tape recorders - the decent ones had bias frequency of 180-200kHz - bias frequency is a raw moral equivalent of sample rate. So, the true improvement comes with higher sample rate - that's why SACD. Whatever ... --Sergei. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On 22-11-07 22:00, Paolo Saggese wrote: (what's worse is that, nevertheless, even now a good analogue system can still sound MUCH better than any CD: it actually takes a good SACD or DVD-A system to come close to the good old LP when it comes to the real perceived audio quality!) If we're talking about a particularly thick LP with one song per side so as to allow for better dynamic range than the utterly pathetic 70 dB or so of a normal LP that is. And, ofcourse, a turntable with motor-control with absolute world-class stability. Particularly difficult one that... And, ofcourse, a world-class element with a completely new needle to turn the groove into electrical signals without distorting it. And, ofcourse, a world-class phono-amplifier to compensate for the cowardly dynamics of LP versus CD, certainly for anything but classic or jazz. And, ofcourse, a completely new record. And, ofcourse... well, you get the point. Other than that, I agree that CD is significantly worse than SACD ;-) Rene. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On Wed, 21 Nov 2007 20:33:39 +0100 Paolo Saggese [EMAIL PROTECTED] wrote: Hi everybody, I have a question for you guys. (I'm new to this list and hope this is the right place to ask and not an FAQ... I've tried to search to see if this question had been answered previously, but I have been not able to find what I was looking for). I'm thinking about using a dedicated (fanless, diskless, etc) PC as a digital source for my hi-end Hi-Fi system. Of course I plan to use the PC only to provide a bitperfect (exact copy of the original media, normally CD) digital stream to an external DAC. As you probably know better than me, the one major known problem when you strive for the highest possible quality in digital audio reproduction is jitter... and the best (if not only) way to really minimize it is to use a good, clean and stable clock close to the DAC chip, slaving everything else to that one. Thus, what I would need to do would be to slave the sound card SPDIF output clock to the external DAC clock i.e. to make this one become the master clock for the whole digital audio stream. AFAIK, one possible way to do this is to set up a fake SPDIF output from the external DAC and connect it to an input of the sound card whose SPDIF output goes to the DAC for conversion. Of course the sound card must be able to slave (synchronize) its SPDIF output clock with the one coming from its SPDIF input. (BTW: are there other -perhaps easier and/or better- ways to do what I would like to do?) Thus, I would need a sound card which must be: * cabable of bitperfect (pass through) operation at CD standard 16bit/44.1KHz (as well as, possibly, also at higher resolutions and sample rates such as 16/48, 24/48, 24/96 and 24/192). * capable of slaving its SPDIF output clock to an external one, such as the one reconstructed from its SPDIF input. last but not least, of course all of this must be done on Linux, thus the sound card must be fully supported by ALSA! 8-) Well, yet another requirement is... that it should possibly (and hopefully) not cost me a fortune! $-) Thanks in advance for your attention. Ciao e grazie, Paolo. -- Skype: Paolo.Saggese http://borex.lngs.infn.it/saggese You can still escape from the GATES of hell: Use Linux! - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user Extracting data digitally from CD is unrelated to soundcard. Perform web search for 'cdparanoia'. In fact, if you want reliable sound, first transfer data from _all_ your audio CDs to HD and then play it from there. Regarding soundcard and syncrhonization - M-Audio Revolution 7.1, and quite possibly M-Audio Revolution allow you to use external clock source. I have never used SPDIFF myself though. Regards, Sergei. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On Wed, 21 Nov 2007 23:19:58 +0200 Sergei Steshenko [EMAIL PROTECTED] wrote: Regarding soundcard and syncrhonization - M-Audio Revolution 7.1, and quite possibly M-Audio Revolution allow you to use external clock source. I meant M-Audio Revolution 7.1, and quite possibly M-Audio Revolution 5.1 allow you to use external clock source. --Sergei. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] best card for bitperfect SPDIF I/O with external clock sync ?
On Wed, 21 Nov 2007, Sergei Steshenko wrote: On Wed, 21 Nov 2007 20:33:39 +0100 Paolo Saggese [EMAIL PROTECTED] wrote: Hi everybody, I have a question for you guys. (I'm new to this list and hope this is the right place to ask and not an FAQ... I've tried to search to see if this question had been answered previously, but I have been not able to find what I was looking for). I'm thinking about using a dedicated (fanless, diskless, etc) PC as a digital source for my hi-end Hi-Fi system. Of course I plan to use the PC only to provide a bitperfect (exact copy of the original media, normally CD) digital stream to an external DAC. As you probably know better than me, the one major known problem when you strive for the highest possible quality in digital audio reproduction is jitter... and the best (if not only) way to really minimize it is to use a good, clean and stable clock close to the DAC chip, slaving everything else to that one. The clock jitter tends to be in the ppm range. This means that the frequency jitter is very low (if I believe the ppm then at the level of -120dB) which is completely inaudible. My cheap Transit card reliably gives me noise levels of the order of -90db below the level of the signal, again inaudible. Thus, what I would need to do would be to slave the sound card SPDIF output clock to the external DAC clock i.e. to make this one become the master clock for the whole digital audio stream. SPDIF is a digital output stream. Its clock is irelevant. The clock on the machine that converts that stream to analog is the important one. AFAIK, one possible way to do this is to set up a fake SPDIF output from the external DAC and connect it to an input of the sound card whose SPDIF output goes to the DAC for conversion. Of course the sound card must be able to slave (synchronize) its SPDIF output clock with the one coming from its SPDIF input. (BTW: are there other -perhaps easier and/or better- ways to do what I would like to do?) Thus, I would need a sound card which must be: * cabable of bitperfect (pass through) operation at CD standard 16bit/44.1KHz (as well as, possibly, also at higher resolutions and sample rates such as 16/48, 24/48, 24/96 and 24/192). bit perfect digitial operation is trivial Almost anything can do that. Computers do it at GHz frequencies so 96KHZ is completely and totally trivial. The only crucial thing is the Digital to analog converter. * capable of slaving its SPDIF output clock to an external one, such as the one reconstructed from its SPDIF input. last but not least, of course all of this must be done on Linux, thus the sound card must be fully supported by ALSA! 8-) Well, yet another requirement is... that it should possibly (and hopefully) not cost me a fortune! $-) Extracting data digitally from CD is unrelated to soundcard. Perform web search for 'cdparanoia'. In fact, if you want reliable sound, first transfer data from _all_ your audio CDs to HD and then play it from there. Regarding soundcard and syncrhonization - M-Audio Revolution 7.1, and quite possibly M-Audio Revolution allow you to use external clock source. I have never used SPDIFF myself though. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
