Re: [LAD] Xiph.org - Video:Digital Show and Tell - No difference between analog and digitally processed sound.
On 05/23/2013 02:18 PM, Fons Adriaensen wrote: On Thu, May 23, 2013 at 09:38:40AM +0200, Jörn Nettingsmeier wrote: moreover, i'd expect src circuits with only -12dB at fs/s to be unusable in practise, because the aliasing artefacts would be obvious. it means the top octave from 10-20hkz would be polluted with junk at -24 to -12dB, It doesn't have to mean that. If the filter gain is -12 dB at 0.5 Fs that doesn't imply it will be -24 dB at Fs - 10 kHz. yes, sorry. i misread that one - for some reason, i had a 12db/oct filter in mind... snip The potential intermodulation effects referred to in the paper by Julian Dunn are real, but not realistic. If such signals (high energy well above 20 kHz) are present you'll have some serious problems even in a completely analog system. probably :) but i found the link between passband ripple and pre-echo really fascinating - this fact was completely new to me. -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio) Tonmeister VDT http://stackingdwarves.net ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Xiph.org - Video:Digital Show and Tell - No difference between analog and digitally processed sound.
hi john, On 05/22/2013 09:44 PM, John Rigg wrote: On Wed, May 22, 2013 at 10:38:37AM -0400, Bill Gribble wrote: There are real effects due to clock jitter on both the A/D and D/A end that can cause small but measurable distortions. Not to mention audible if it's severe enough. Decimation filters that only give 6 or 12dB attenuation at fs/2 (typical in many pro audio ADC chips) can allow audible aliasing too. I wouldn't expect an oscilloscope to have enough resolution to detect these effects, but a good spectrum analyser and/or a good pair of ears often can. this comment raised my eyebrows a little bit. can you explain what you mean by decimation filter? the way i understand it, decimation means chopping off bits, usually by shifting the data words, and possibly adding dither. how can this be a problem at fs/2? no new frequency components are introduced (apart from additional quantisation noise, which must necessarily be band-limited to fs/2), and the input of the decimation stage will already be band-limited as well. otoh, if you mean sample rate down-conversion, i understand your comment, but then you picked an unfortunate term. moreover, i'd expect src circuits with only -12dB at fs/s to be unusable in practise, because the aliasing artefacts would be obvious. it means the top octave from 10-20hkz would be polluted with junk at -24 to -12dB, unless of course there are some oversampling tricks going on and the effective fs is higher during down conversion. although i must confess i don't know anything about DAC and SRC design - if someone can explain this in more detail, i'm all ears. best, jörn -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio) Tonmeister VDT http://stackingdwarves.net ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Xiph.org - Video:Digital Show and Tell - No difference between analog and digitally processed sound.
On Thu, May 23, 2013 at 09:38:40AM +0200, Jörn Nettingsmeier wrote: moreover, i'd expect src circuits with only -12dB at fs/s to be unusable in practise, because the aliasing artefacts would be obvious. it means the top octave from 10-20hkz would be polluted with junk at -24 to -12dB, It doesn't have to mean that. If the filter gain is -12 dB at 0.5 Fs that doesn't imply it will be -24 dB at Fs - 10 kHz. Take a filter for a 48 kHz DAC. It could be -0.5 dB at 23 kHz, -12 dB at 24 kHz, and -100 dB at 25 kHz. Any aliasing will be either above 23 kHz or below -100 dB, probably harmless. Given the passband and stopband constraints at 23 and 25 kHz, the actual value at 24 kHz is more or less irrelevant. The potential intermodulation effects referred to in the paper by Julian Dunn are real, but not realistic. If such signals (high energy well above 20 kHz) are present you'll have some serious problems even in a completely analog system. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Xiph.org - Video:Digital Show and Tell - No difference between analog and digitally processed sound.
On Thu, May 23, 2013 at 12:18:25PM +, Fons Adriaensen wrote: Take a filter for a 48 kHz DAC. It could be -0.5 dB at 23 kHz, -12 dB at 24 kHz, and -100 dB at 25 kHz. Any aliasing will be either above 23 kHz or below -100 dB, probably harmless. Given the passband and stopband constraints at 23 and 25 kHz, the actual value at 24 kHz is more or less irrelevant. The potential intermodulation effects referred to in the paper by Julian Dunn are real, but not realistic. If such signals (high energy well above 20 kHz) are present you'll have some serious problems even in a completely analog system. True, although I'd have more confidence in a filter that eliminated the possibility entirely. I couldn't resist responding to the statement in the thread title: No difference between analog and digitally processed sound. As in so many things, that depends. John ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
[LAD] Xiph.org - Video:Digital Show and Tell - No difference between analog and digitally processed sound.
Thought the list would find this valuable. http://wiki.xiph.org/Videos/Digital_Show_and_Tell I was under the impression that there was some fundamental difference between the sound of analog and digital audio. But Monty Montgomery of Xiph.org completely annihilates this misconception with some clever use of analog sound reference equipment fed through a digital process and then out to an analog oscilloscope, vs. feeding direct from analog to the oscilloscope. The results are identical. I think Xiph have done the open source music community quite a service here because it completely trumps, in my opinion, the perception that electronic music put through a digital process is somehow inferior to analog music. ~~~ Home site - http://djbarney.org ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Xiph.org - Video:Digital Show and Tell - No difference between analog and digitally processed sound.
That is a nice video indeed. See also the other video from there A digital primer or so. This was supposed to be my next Share and Care entry for my blog nilsgey.de I guess it doens't hurt to spread knowledge through as many channels as possible. Nils On Wed, 22 May 2013 15:08:38 +0100 Barney Holmes djbar...@djbarney.org wrote: Thought the list would find this valuable. http://wiki.xiph.org/Videos/Digital_Show_and_Tell I was under the impression that there was some fundamental difference between the sound of analog and digital audio. But Monty Montgomery of Xiph.org completely annihilates this misconception with some clever use of analog sound reference equipment fed through a digital process and then out to an analog oscilloscope, vs. feeding direct from analog to the oscilloscope. The results are identical. I think Xiph have done the open source music community quite a service here because it completely trumps, in my opinion, the perception that electronic music put through a digital process is somehow inferior to analog music. ~~~ Home site - http://djbarney.org ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Xiph.org - Video:Digital Show and Tell - No difference between analog and digitally processed sound.
This is an interesting video, and for their stated purpose (to dispel the idea that the output of a D/A converter is a stairstep) it's great. But, to be fair, he's only addressing one part of the process (the conversion from analog to digital and back). Arguments about analog and digital in recording tend to include such things as tape saturation, transformers, vinyl cutting technique, floating-point error, plugin aliasing, etc which are separate issues from A/D and D/A and are as much about what sounds good as about whether a sampled signal can be perfectly reconstructed. Also, the demonstrations with the oscilloscope are illuminating regarding the math behind digital audio, but those aren't exactly precision measurements. There are real effects due to clock jitter on both the A/D and D/A end that can cause small but measurable distortions. Ideal sampling and reconstruction requires ideal hardware, which (as you might guess) doesn't exist! The amount of non-ideal behavior may not bother you, for any particular value of you, but then again it may. Thanks, Bill Gribble On Wed, 2013-05-22 at 15:08 +0100, Barney Holmes wrote: Thought the list would find this valuable. http://wiki.xiph.org/Videos/Digital_Show_and_Tell I was under the impression that there was some fundamental difference between the sound of analog and digital audio. But Monty Montgomery of Xiph.org completely annihilates this misconception with some clever use of analog sound reference equipment fed through a digital process and then out to an analog oscilloscope, vs. feeding direct from analog to the oscilloscope. The results are identical. I think Xiph have done the open source music community quite a service here because it completely trumps, in my opinion, the perception that electronic music put through a digital process is somehow inferior to analog music. ~~~ Home site - http://djbarney.org ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Xiph.org - Video:Digital Show and Tell - No difference between analog and digitally processed sound.
Nice blog ! Talking of sharing and caring I'm very interested in the MIT course linked at the bottom of that article. There must be lots of other music and music related online courses from institutions like MIT. I wonder if they are listed anywhere ? On Wed, May 22, 2013 3:16 pm, Nils Gey wrote: That is a nice video indeed. See also the other video from there A digital primer or so. This was supposed to be my next Share and Care entry for my blog nilsgey.de I guess it doens't hurt to spread knowledge through as many channels as possible. Nils On Wed, 22 May 2013 15:08:38 +0100 Barney Holmes djbar...@djbarney.org wrote: Thought the list would find this valuable. http://wiki.xiph.org/Videos/Digital_Show_and_Tell I was under the impression that there was some fundamental difference between the sound of analog and digital audio. But Monty Montgomery of Xiph.org completely annihilates this misconception with some clever use of analog sound reference equipment fed through a digital process and then out to an analog oscilloscope, vs. feeding direct from analog to the oscilloscope. The results are identical. I think Xiph have done the open source music community quite a service here because it completely trumps, in my opinion, the perception that electronic music put through a digital process is somehow inferior to analog music. ~~~ Home site - http://djbarney.org ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev ~~~ Home site - http://djbarney.org ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Xiph.org - Video:Digital Show and Tell - No difference between analog and digitally processed sound.
On Wed, May 22, 2013 at 10:38:37AM -0400, Bill Gribble wrote: There are real effects due to clock jitter on both the A/D and D/A end that can cause small but measurable distortions. Not to mention audible if it's severe enough. Decimation filters that only give 6 or 12dB attenuation at fs/2 (typical in many pro audio ADC chips) can allow audible aliasing too. I wouldn't expect an oscilloscope to have enough resolution to detect these effects, but a good spectrum analyser and/or a good pair of ears often can. John ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
