Jon Harris wrote:> "Arthur" <arthurc99@yahoo.com> wrote in message > news:c65haq$1dgf$1@news.hgc.com.hk... > >>Hello all, >> >>Recently, there is a tendency to use high sampling rate 96 KHz, 192 KHz in >>the audio application. To my knowledge, about ~ 20 KHz, everything will be >>cut off from the loudspeaker, amplifier, etc.. So, why 96 KHz, 192 KHz >>instead of 48 KHz.. > > > Apart from the issue of audible bandwidth, having more frequency "headroom" is > useful. Digital filters tend to go a bit crazy near the Nyquist frequency, so > moving that frequency well above the accepted audible range is a good thing. As > has been pointed out by others, frequency headroom also simplifies the analog > input/output filtering stages as well as sample rate conversion. Remember that > the Nyquist criteria states that it is _possible_ to perfectly reconstruct the > original waveform, but not that it is _practical_ or _easy_ to do so. Increased > frequency headroom generally makes it easier.That's true, of course. I think that the important question is, "How much is enough?" and the answer is very dependent on context. Good engineering involves compromise; many are implicit here. Given a fixed number of bits in a medium, apportion them among word size, error recovery, sample rate, and playing time to give the user the best perceived value. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
What is the advantage on high-sampling rate ?
Started by ●April 21, 2004
Reply by ●April 21, 20042004-04-21
Reply by ●April 21, 20042004-04-21
"Jerry Avins" <jya@ieee.org> wrote in message news:4086d7ca$0$16450$61fed72c@news.rcn.com...> Jon Harris wrote: > > > "Arthur" <arthurc99@yahoo.com> wrote in message > > news:c65haq$1dgf$1@news.hgc.com.hk... > > > >>Hello all, > >> > >>Recently, there is a tendency to use high sampling rate 96 KHz, 192 KHz in > >>the audio application. To my knowledge, about ~ 20 KHz, everything will be > >>cut off from the loudspeaker, amplifier, etc.. So, why 96 KHz, 192 KHz > >>instead of 48 KHz.. > > > > > > Apart from the issue of audible bandwidth, having more frequency "headroom"is> > useful. Digital filters tend to go a bit crazy near the Nyquist frequency,so> > moving that frequency well above the accepted audible range is a good thing.As> > has been pointed out by others, frequency headroom also simplifies theanalog> > input/output filtering stages as well as sample rate conversion. Rememberthat> > the Nyquist criteria states that it is _possible_ to perfectly reconstructthe> > original waveform, but not that it is _practical_ or _easy_ to do so.Increased> > frequency headroom generally makes it easier. > > That's true, of course. I think that the important question is, "How > much is enough?" and the answer is very dependent on context. Good > engineering involves compromise; many are implicit here. Given a fixed > number of bits in a medium, apportion them among word size, error > recovery, sample rate, and playing time to give the user the best > perceived value.I agree. The DVD-A standard is kind of nice this way in that you can trade off sample rate/bit depth/number of channels/playing time, at least from what I understand of the format. Regarding "fixed number of bits" the vast increase in this number due to DVDs and cheap large hard drives really kick started this whole higher sampling rate craze. I think Randy pointed out a while back that if the object was just to allow more headroom, a more sensible sample rate would be around 64K. An aside... I often think about the waste in using conventional audio CDs for "books on tape". A book often requires many CDs, maybe even dozens. You end up with a mono source with fairly limited dynamic range and frequency content being recorded onto a stereo, 16-bit, 44.1kHz medium. You could increase your playback time by at least a factor of 4 just by switching to mono/22kHz, which would be very adequate for the task. But I guess this problem is solved now by the use of MP3/WMA files stored on CDs. With psychoacoustic compression, quality is still very good and playback times can be increased 10x or more vs. audio CD with this method. Unfortunately, there aren't many (any?) commercially available recordings in this format yet.
Reply by ●April 21, 20042004-04-21
Jon Harris wrote:> I often think about the waste in using conventional audio CDs for "books on > tape". A book often requires many CDs, maybe even dozens. You end up with a > mono source with fairly limited dynamic range and frequency content being > recorded onto a stereo, 16-bit, 44.1kHz medium. You could increase your > playback time by at least a factor of 4 just by switching to mono/22kHz, which > would be very adequate for the task.Ha! Not if the audio book is read by, say, Gillian Anderson; you definitely don't want to miss a single Hz from her original voice's bandwith! :-) Carlos --
Reply by ●April 22, 20042004-04-22
On Wed, 21 Apr 2004 16:21:15 -0400, Jerry Avins wrote:> That's true, of course. I think that the important question is, "How > much is enough?" and the answer is very dependent on context. Good > engineering involves compromise; many are implicit here. Given a fixed > number of bits in a medium, apportion them among word size, error > recovery, sample rate, and playing time to give the user the best > perceived value.Or do what DVD-A has done, and allow the producer to make that decision on a case-by-case basis. Even on-the-fly. When the size of a bucket of bits is so large, why wouldn't you spend some to make life easier? -- Andrew
Reply by ●April 22, 20042004-04-22
Hi Arthur, For me the advantage to have a high sampling rate is to obtain more samples in one second and as a consequence to reproduce with more efficiency the analog signal you sample. For me it's the only reason why sample audio frequency like 96KHz or 192 KHz have appeared. Maybe I'm wrong but i give you my point of view. The advantage is certainly not to be able to sample signals containing higher frequencies than 20 KHz since the human beings can't hear sounds with frequency higher than about 16 KHz. Bye. Jerome "Arthur" <arthurc99@yahoo.com> wrote in message news:<c65haq$1dgf$1@news.hgc.com.hk>...> Hello all, > > Recently, there is a tendency to use high sampling rate 96 KHz, 192 KHz in > the audio application. To my knowledge, about ~ 20 KHz, everything will be > cut off from the loudspeaker, amplifier, etc.. So, why 96 KHz, 192 KHz > instead of 48 KHz.. > > Regards > Arthur
Reply by ●April 22, 20042004-04-22
Hi Arthur, For me the advantage to have a high sampling rate is to obtain more samples in one second and as a consequence to reproduce with more efficiency the analog signal you sample. For me it's the only reason why sample audio frequency like 96KHz or 192 KHz have appeared. Maybe I'm wrong but i give you my point of view. The advantage is certainly not to be able to sample signals containing higher frequencies than 20 KHz since the human beings can't hear sounds with frequency higher than about 16 KHz. Bye. Jerome "Arthur" <arthurc99@yahoo.com> wrote in message news:<c65haq$1dgf$1@news.hgc.com.hk>...> Hello all, > > Recently, there is a tendency to use high sampling rate 96 KHz, 192 KHz in > the audio application. To my knowledge, about ~ 20 KHz, everything will be > cut off from the loudspeaker, amplifier, etc.. So, why 96 KHz, 192 KHz > instead of 48 KHz.. > > Regards > Arthur
Reply by ●April 22, 20042004-04-22
Jerry Avins wrote:> > Many people who decide on their own end up buying centimeter-diameter > gold-plated loudspeaker wire. Having spent an outrageous amount for the > cables, they will inevitably hear the improvement these cables make.Oh yes. Not to mention the "voodoo" products like the Furutech disk demagnetizer: http://www.furutech.com/new1/produ_2.asp?ProdNo=68 One of my favorites... :-) --smb
Reply by ●April 22, 20042004-04-22
french_student wrote:> Hi Arthur, > > For me the advantage to have a high sampling rate is to obtain more > samples in one second and as a consequence to reproduce with more > efficiency the analog signal you sample.Assuming suitable filters, a sample rate so high that more than two samples occur during one period of the highest frequency, the reproduction can be perfect. Sampling at a rate that allows 2.5 samples makes the filter design easier. \> For me it's the only reason why sample audio frequency like 96KHz or > 192 KHz have appeared. Maybe I'm wrong but i give you my point of > view. > The advantage is certainly not to be able to sample signals containing > higher frequencies than 20 KHz since the human beings can't hear > sounds with frequency higher than about 16 KHz.When I wrote "the reproduction can be perfect" above, I meant it. Perfection can't be improved. As for the upper limit of hearing, by daughter could hear up to 22,000 Hz. It was a curse, not a blessing.> Bye. > JeromeJerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●April 22, 20042004-04-22
Carlos Moreno <moreno_at_mochima_dot_com@xx.xxx> wrote in message news:<devhc.134913$wo6.1957145@wagner.videotron.net>...> Arthur wrote: > > > Hello all, > My point is that higher sampling rates do help, although > arguably they're not strictly necessary. Then again, the > "more-bits-more-sampling-rate-is-better-comma-buy-the-new- > and-improved-super-digital-equipment" syndrome is part of > the mix. > > Carlos > --How timely of you. I just posted a white paper on my web site at: www.lavryengineering.com under the Support section. The paper is "Sampling Theory" is 26 pages long and deals a lot with this question extansivly. It is made on Mathcad, but I kept the equations out of the final document, so it is text and a lot of graphs. If you do not want to read it, here is a summary as to the 192KHz benefits: Advantages - none. The paper takes apart the false arguments of "more dots for more detail", the narrower impulse response BS, the old anti alias steep filter (needed in the 1980 before over sampling days) and more. Disadvantages - lower accuracy (speed vs accuracy tradeoff and more), large files (takes more space, slower to move around), increased signal processing requirements (thus costs) 192KHz sampling for audio is a crock. A marketing tool to help big companies control the market and sell new gear. While 44.1KHz may be a bit slow, by the time you get to 88.2KHz or 96KHz, it is already an overkill. Much of the 192KHz was driven by the business and marketing departments. The EE's, scientists, audiologists, mathematicians are normally not invited to comment. Many admitted to me they are afraid to take a stand due to potential economic consequences. Not all EE's understand signal theory and information theory, but those that do, know that "more dots is better" is not true for band limited signals (Nyquist Theorem). So the crowd is being herded to the 192KHz by use of wrong premises that appeals to their common sense. "More pixels for video are better" does not mean "more samples for audio is better". It may go against everyday simple common sense, but so are many other things. Nyquist's contribution was so great because it went beyond simple common sense. BR Dan Lavry Lavry Engineering
Reply by ●April 22, 20042004-04-22
"dan lavry" <danlavry@mindspring.com> wrote in message news:673b149b.0404220848.3f4465fe@posting.google.com...> Carlos Moreno <moreno_at_mochima_dot_com@xx.xxx> wrote in messagenews:<devhc.134913$wo6.1957145@wagner.videotron.net>...> > Arthur wrote: > > > > > Hello all, > > My point is that higher sampling rates do help, although > > arguably they're not strictly necessary. Then again, the > > "more-bits-more-sampling-rate-is-better-comma-buy-the-new- > > and-improved-super-digital-equipment" syndrome is part of > > the mix. > > How timely of you. > I just posted a white paper on my web site at: > www.lavryengineering.com under the Support section. > The paper is "Sampling Theory" is 26 pages long and deals a lot with > this question extansivly. It is made on Mathcad, but I kept the > equations out of the final document, so it is text and a lot of > graphs.<snip> There is also a good article called "Pulse-Code Modulation - An Overview" by Lipshitz and Vanderkooy in the March 2004 AES journal.
