"Richard Crowley" <rcrowley7@xprt.net> wrote in message news:10aola6pnbau090@corp.supernews.com...> > Of course true "1-bit" audio is indistinguishable from > random noise.Not really. DSD is one bit (at a very high sampling rate) and certainly doesn't sound like random noise. Even with "regular" sample rates such as 44.1kHz, so you can still recognize properly-dithered audio at very low bit depths (even 1 bit). The audio is buried in noise, just like it would sound if you recorded at very low levels on a medium such as cassette tape, but the ear is pretty good at pulling out the real sound from the noise.
1-Bit Wave File?
Started by ●May 16, 2004
Reply by ●May 20, 20042004-05-20
Reply by ●May 20, 20042004-05-20
Randy Yates wrote:>>> Bit-depth reducing to 1 bit does not convert PCM into a PWM signal. >>> >> >> On the other hand, I guess it does, > > Absolutely it does not. A PWM signal has the property that at > time n*T the signal begins at a high state for p*T seconds and > ends at a low state for (1-p)*T seconds, 0 <= p <= 1. A 1-bit > bitstream does not have this property. > > Many people seem to have this misconception that a delta sigma > bitstream is a PWM waveform. It is not - they are two different > animals.I was alluding to the resultant signal being an asymetrical bitstream, like a PWM signal. Though I did qualify that it bears no relationship to any encoded signal. One "1", followed by one "0", then two "1"s followed by a "0" looks PWM to me. geoff
Reply by ●May 20, 20042004-05-20
"Geoff Wood" <geoff@paf.co.nz-nospam> writes:> Randy Yates wrote: > > >>> Bit-depth reducing to 1 bit does not convert PCM into a PWM signal. > >>> > >> > >> On the other hand, I guess it does, > > > > Absolutely it does not. A PWM signal has the property that at > > time n*T the signal begins at a high state for p*T seconds and > > ends at a low state for (1-p)*T seconds, 0 <= p <= 1. A 1-bit > > bitstream does not have this property. > > > > Many people seem to have this misconception that a delta sigma > > bitstream is a PWM waveform. It is not - they are two different > > animals. > > I was alluding to the resultant signal being an asymetrical bitstream, like > a PWM signal.I have no idea what you mean.> Though I did qualify that it bears no relationship to any > encoded signal.What is "it"?> One "1", followed by one "0", then two "1"s followed by a "0" looks PWM to > me.How so? It doesn't match any definition of PWM that I know of. When I talk about PWM, I mean, e.g., the type of signal shown in figure one of http://www.embedded.com/story/OEG20010821S0096 -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA randy.yates@sonyericsson.com, 919-472-1124
Reply by ●May 20, 20042004-05-20
On Fri, 21 May 2004 08:40:43 +1200, "Geoff Wood" <geoff@paf.co.nz-nospam> wrote:>Randy Yates wrote: > >>>> Bit-depth reducing to 1 bit does not convert PCM into a PWM signal. >>>> >>> >>> On the other hand, I guess it does, >> >> Absolutely it does not. A PWM signal has the property that at >> time n*T the signal begins at a high state for p*T seconds and >> ends at a low state for (1-p)*T seconds, 0 <= p <= 1. A 1-bit >> bitstream does not have this property. >> >> Many people seem to have this misconception that a delta sigma >> bitstream is a PWM waveform. It is not - they are two different >> animals. > >I was alluding to the resultant signal being an asymetrical bitstream, like >a PWM signal. Though I did qualify that it bears no relationship to any >encoded signal. > >One "1", followed by one "0", then two "1"s followed by a "0" looks PWM to >me. > >geoff >Just to be sure - there are no digits in PWM - it is an analogies system. It is sampled, to be sure, but not digitally. d Pearce Consulting http://www.pearce.uk.com
Reply by ●May 20, 20042004-05-20
"Richard Crowley" <rcrowley7@xprt.net> wrote in message news:<10aola6pnbau090@corp.supernews.com>...> > Of course true "1-bit" audio is indistinguishable from > random noise. >In a word, wrong. In two words, completely wrong. A 1-bit stream is perfectly capable of holding quite intelligible audio. It will have a broadband dynamic range of only 6 dB, but that is quite enough for intelligible speech and easily recognizable music. You should maybe review works such as Lipshitz and Vanderkooy's "Resolution below the least significant bit in audio systems with dither" from JAES before making such a pronouncement.
Reply by ●May 20, 20042004-05-20
"Randy Yates" <randy.yates@sonyericsson.com> wrote in message news:xxp65aqg529.fsf@usrts005.corpusers.net...> "Geoff Wood" <geoff@paf.co.nz-nospam> writes: > > > Randy Yates wrote: > > > > >>> Bit-depth reducing to 1 bit does not convert PCM into a PWM signal. > > >>> > > >> > > >> On the other hand, I guess it does, > > > > > > Absolutely it does not. A PWM signal has the property that at > > > time n*T the signal begins at a high state for p*T seconds and > > > ends at a low state for (1-p)*T seconds, 0 <= p <= 1. A 1-bit > > > bitstream does not have this property. > > > > > > Many people seem to have this misconception that a delta sigma > > > bitstream is a PWM waveform. It is not - they are two different > > > animals. > > > > I was alluding to the resultant signal being an asymetrical bitstream, like > > a PWM signal. > > I have no idea what you mean. > > > Though I did qualify that it bears no relationship to any > > encoded signal. > > What is "it"? > > > One "1", followed by one "0", then two "1"s followed by a "0" looks PWM to > > me. > > How so? It doesn't match any definition of PWM that I know of. When I talk > about PWM, I mean, e.g., the type of signal shown in figure one of > > http://www.embedded.com/story/OEG20010821S0096Randy, I don't see any reason why you couldn't create the waveforms shown in Fig. 1 above with a 1-bit PCM waveform, assuming sufficient sample rate. -Jon
Reply by ●May 20, 20042004-05-20
"Jon Harris" <goldentully@hotmail.com> writes:> "Randy Yates" <randy.yates@sonyericsson.com> wrote in message > news:xxp65aqg529.fsf@usrts005.corpusers.net... > > "Geoff Wood" <geoff@paf.co.nz-nospam> writes: > > > > > Randy Yates wrote: > > > > > > >>> Bit-depth reducing to 1 bit does not convert PCM into a PWM signal. > > > >>> > > > >> > > > >> On the other hand, I guess it does, > > > > > > > > Absolutely it does not. A PWM signal has the property that at > > > > time n*T the signal begins at a high state for p*T seconds and > > > > ends at a low state for (1-p)*T seconds, 0 <= p <= 1. A 1-bit > > > > bitstream does not have this property. > > > > > > > > Many people seem to have this misconception that a delta sigma > > > > bitstream is a PWM waveform. It is not - they are two different > > > > animals. > > > > > > I was alluding to the resultant signal being an asymetrical bitstream, like > > > a PWM signal. > > > > I have no idea what you mean. > > > > > Though I did qualify that it bears no relationship to any > > > encoded signal. > > > > What is "it"? > > > > > One "1", followed by one "0", then two "1"s followed by a "0" looks PWM to > > > me. > > > > How so? It doesn't match any definition of PWM that I know of. When I talk > > about PWM, I mean, e.g., the type of signal shown in figure one of > > > > http://www.embedded.com/story/OEG20010821S0096 > > > Randy, > > I don't see any reason why you couldn't create the waveforms shown in Fig. 1 > above with a 1-bit PCM waveform, assuming sufficient sample rate.Jon, I'm not saying you can't generate PWM digitally. Yes, I agree that you can. I'm saying that when you requantize a multi-bit waveform to 1 bit (just a simple requantization, like when you requantize from 24 bits to 16 bits, but this time you go all the way down to 1 bit), the result will NOT be a PWM signal. I'm also saying that if you perform a delta sigma conversion of a multi-bit waveform to a 1-bit waveform (i.e., perform a delta sigma D/A conversion and examine the 1-bit bistream before it is converted to analog), the result will NOT be a PWM signal. -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA randy.yates@sonyericsson.com, 919-472-1124
Reply by ●May 20, 20042004-05-20
On Thu, 20 May 2004 21:37:27 GMT, donald@pearce.uk.com (Don Pearce) wrote:>On Fri, 21 May 2004 08:40:43 +1200, "Geoff Wood" ><geoff@paf.co.nz-nospam> wrote: > >>Randy Yates wrote: >> >>>>> Bit-depth reducing to 1 bit does not convert PCM into a PWM signal. >>>>> >>>> >>>> On the other hand, I guess it does, >>> >>> Absolutely it does not. A PWM signal has the property that at >>> time n*T the signal begins at a high state for p*T seconds and >>> ends at a low state for (1-p)*T seconds, 0 <= p <= 1. A 1-bit >>> bitstream does not have this property. >>> >>> Many people seem to have this misconception that a delta sigma >>> bitstream is a PWM waveform. It is not - they are two different >>> animals. >> >>I was alluding to the resultant signal being an asymetrical bitstream, like >>a PWM signal. Though I did qualify that it bears no relationship to any >>encoded signal. >> >>One "1", followed by one "0", then two "1"s followed by a "0" looks PWM to >>me. >> >>geoff >> > >Just to be sure - there are no digits in PWM - it is an analogies >system. It is sampled, to be sure, but not digitally. > >d >Pearce Consulting >http://www.pearce.uk.comGood old spell-checker! Make that "analogue". d Pearce Consulting http://www.pearce.uk.com
Reply by ●May 20, 20042004-05-20
Dick Pierce wrote:> "Richard Crowley" <rcrowley7@xprt.net> wrote in message news:<10aola6pnbau090@corp.supernews.com>... > >>Of course true "1-bit" audio is indistinguishable from >>random noise. >> > > > In a word, wrong. In two words, completely wrong. > > A 1-bit stream is perfectly capable of holding quite intelligible > audio. It will have a broadband dynamic range of only 6 dB, but > that is quite enough for intelligible speech and easily recognizable > music.Please read the thread and don't try to justify balf-baked ideas. We all know that data coming one bit at a time can be useful: this message will be transmitted that way. According to what he asked for, the OP wants to strip all but the sign bit from a wave file in hopes of getting "that old movie sound".> You should maybe review works such as Lipshitz and Vanderkooy's > "Resolution below the least significant bit in audio systems with > dither" from JAES before making such a pronouncement.Why? It's irrelevant to this thread. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●May 20, 20042004-05-20
Me <secad@netspace.net.au> wrote in message news:<c8i3fp$1kpk$1@otis.netspace.net.au>...> Curious wrote: > > > I am looking for audio software that allows conversion of 16-bit WAVs > > and 8-bit WAVs to 1-bit WAVs. I have used Adobe Audition and CakeWalk > > Pyro. Neither of them work. CakeWalk does have a "bit-depth converter" > > as a FX, however, when I try to use it, I get a runtime error and > > Cakewalk automatically closes. > > A + Comparator FlipFlop > I/P -------|\ +------+ Q > | >----------| D Q|---+---- Bitstream out > B +--|/ C +--|> | | > | - | +------+ | > | | | > +-/\/\/\-----)-------------+ > | R | > C === | > | Fs---+ > 0V > > Several years ago I made a delay line to delay the audio for a walkie-talkie > so that the Tx VOX voice operated switch and Rx unmute operation would be > completed before the leading word spoken by the operator was transmitted. > I tried a bucket brigade device (MN3001) but had troubles with noise and > limitations on maximum delay. > > I tried the cct above as a 1-bit encoder (mentioned in a mag somewhere), > clocked at over 200KHz. I do not know if the cct has a name. >The above circuit looks to me very much like an implementation of a delta modulator, the RC circuit being a lossy integrator. This is the forunner to delta-sigma isn't it? Paavo Jumppanen Author of HarBal Harmonic Balancer http://www.har-bal.com
