[spiney2]

Quote:

Originally Posted by chrisjr

There is ONE surround channel not two! Are you going to argue that there are two centre channels based on that matrix equation table?

The single surround channel is fed to both left and right total channels with different phase shifts in each channel. On decoding the phase shifts allow the single surround channel to be recreated from the left and right channels.

Just because there are -j and + j phase shifts applied to the portion of the surround channel fed to each of the Lt and Rt channels it in no way means there are two surround channels.

Why do you think that all the Dolby decoders only have a single solitary socket for the surround output?

so are there 2 surround channels covering 90 degrees each, or just one covering 180 degrees, or 4 pro logic 2,channels covering 45 degrees .......?

[spiney2]

i deny stereo exists. Its just mono twice. All else is mere flim flam. Damn my bacon sandwich has gone cold .....

[spiney2]

Quote:

Originally Posted by Deacon1972

Phase coded, in phase, out of phase, there is still only one channel of information.

The mono signal is split into two, then carried by LT/RT out of phase.

One channel, one output, two speakers (home use) numerous speakers (cinema use)

out of phase with what ?,if u invert, then add, it just vanishes ..... "invert the polarity" ......

[spiney2]

if there is just one rear channel, then just plug in 1 speaker and put it at back,..... since both speakers output same thing anyway ......

[chrisjr]

Quote:

Originally Posted by spiney2

a,weird thought has occurred to me. Folks DO know how stereo works? ie phase to amplitude then back to phase .......... ? Its mostly phase that gives position

Stereo in it's most basic form using two microphones uses amplitude and timing differences in the sound arriving at the microphones to create the sound stage.

A multi mic recording uses simple amplitude differences between left and right channels to position each mic in the sound stage.

[Deacon1972]

Quote:

Originally Posted by spiney2

out of phase with what ?,if u invert, then add, it just vanishes ..... "invert the polarity" ......

The surround channel is carried by LT/RT out of phase +/-j (j =90°).

[Deacon1972]

Quote:

Originally Posted by spiney2

if there is just one rear channel, then just plug in 1 speaker and put it at back,..... since both speakers output same thing anyway ......

Some listeners used a single bi-pole or di-pole speaker for the receivers that only had a single output, this gave better rear ambient effects, these were dropped when twin outputs were introduced as two direct radiator speakers gave the desired effect, but bi/di-poles are still used today, I use a pair of THX Select 2 bi-poles.

[anthony david]

In Dolby surround, apart from space ships departing behind you, the surround channel is never used on its own as such a mix is not mono compatible. The pleasant ambient effects are are mix of the front and surround channel. As such mixes are inherently unstable monitoring has to be via a coder/decoder (not the 5 channel desk o/p). In the early days Dolby insisted on a Dolby Consultant to be present at the final mix and for his name to appear on the credits, another reason why you don't see a Dolby Logo on TV productions even if they are mixed that way. The slightly different mixes for the two systems, together with bass management problems, is why some feature films have a Dolby 2ch as well as a 5.1 mix. Down mixing on the fly, in a DVD player perhaps, gives a pleasant sound but may not be quite what the director intended. As most home A/V systems have 5.1 this is no longer so important and as a result most domestically released films, DVD etc, have 5.1 only. Broadcasters will have both versions at their disposal.

Dolby Surround is allied to the Sansui QS system hence their chips in some professional decoders. The CBS SQ system cannot produce an image in the centre of the sound field, everything cancels out to nothing if you try, as Walter/Wendy Carlos found out when CBS released an SQ only version of the album Sonic Seasonings, parts of the mix disappeared.

Both Dolby Prologic and Sansui QS Variomatrix use variable phase cancellation to improve perceived separation. The old CBS SQ decoders used variable gain cells which had unpleasant side effects.

Some Decoders used a set of taps on the rear channel delay line to produce a comb filter which spreads out the rear sound but needs two amps instead of one, I can't remember if cinema systems use this method or not but I suspect some did. 5.1 has of course largely replaced Dolby Surround in the commercial cinema industry.

This isn't for spiney2 by the way as he will think it is just a history lesson.

[spiney2]

Quote:

Originally Posted by chrisjr

Stereo in it's most basic form using two microphones uses amplitude and timing differences in the sound arriving at the microphones to create the sound stage.

A multi mic recording uses simple amplitude differences between left and right channels to position each mic in the sound stage.

very muddled. How does "timing" differ from phase ?

[spiney2]

Quote:

Originally Posted by anthony david

In Dolby surround, apart from space ships departing behind you, the surround channel is never used on its own as such a mix is not mono compatible. The pleasant ambient effects are are mix of the front and surround channel. As such mixes are inherently unstable monitoring has to be via a coder/decoder (not the 5 channel desk o/p). In the early days Dolby insisted on a Dolby Consultant to be present at the final mix and for his name to appear on the credits, another reason why you don't see a Dolby Logo on TV productions even if they are mixed that way. The slightly different mixes for the two systems, together with bass management problems, is why some feature films have a Dolby 2ch as well as a 5.1 mix. Down mixing on the fly, in a DVD player perhaps, gives a pleasant sound but may not be quite what the director intended. As most home A/V systems have 5.1 this is no longer so important and as a result most domestically released films, DVD etc, have 5.1 only. Broadcasters will have both versions at their disposal.

Dolby Surround is allied to the Sansui QS system hence their chips in some professional decoders. The CBS SQ system cannot produce an image in the centre of the sound field, everything cancels out to nothing if you try, as Walter/Wendy Carlos found out when CBS released an SQ only version of the album Sonic Seasonings, parts of the mix disappeared.

Both Dolby Prologic and Sansui QS Variomatrix use variable phase cancellation to improve perceived separation. The old CBS SQ decoders used variable gain cells which had unpleasant side effects.

Some Decoders used a set of taps on the rear channel delay line to produce a comb filter which spreads out the rear sound but needs two amps instead of one, I can't remember if cinema systems use this method or not but I suspect some did. 5.1 has of course largely replaced Dolby Surround in the commercial cinema industry.

This isn't for spiney2 by the way as he will think it is just a history lesson.

in fact its quite interesting. And thanks for not posting any drivel. Comb filters not used by dolby on original system. Wendy carlos has interesting website with big quadrophonics section.

[spiney2]

Quote:

Originally Posted by Deacon1972

The surround channel is carried by LT/RT out of phase +/-j (j =90°).

if u pan the same mono signal both left and right progressively then at exactly 180 degrees it will self cancel and vanish ...... one limitation of matrix compared with discreet ........

[spiney2]

obviously dolby 2.0 is,compatible with mono. Lots of cinemas had mono sound back then. and whooshing spaceships somtimes use "just the back speakers" ........

[chrisjr]

Quote:

Originally Posted by spiney2

very muddled. How does "timing" differ from phase ?

You can call it phase if you want. Just that if you consider a point source of sound somewhere to your left it will hit your left ear very slightly ahead of your right ear. So perhaps more correct to talk in terms of time delay than phase. There will also be a slight amplitude difference between the two ears as well to further localise the source of the sound.

A simple stereo pair of microphones slung in front of a group of musicians for example will capture both amplitude difference and time delay information which will be recorded and reproduced by the loudspeakers.

But if you are mixing a load of single mics or other audio sources down to stereo the positional information in the stereo mix is entirely amplitude based. Any time delays the listener perceives are a product of hearing sound from two loudspeakers with two ears. They are not there in the mix.

[spiney2]

Quote:

Originally Posted by Deacon1972

Some listeners used a single bi-pole or di-pole speaker for the receivers that only had a single output, this gave better rear ambient effects, these were dropped when twin outputs were introduced as two direct radiator speakers gave the desired effect, but bi/di-poles are still used today, I use a pair of THX Select 2 bi-poles.

the earliest home decoders had only 1 rear channel. But since prologic has 2, just using 1 speaker which doesn't give surround sound is rather silly.

[spiney2]

Quote:

Originally Posted by chrisjr

You can call it phase if you want. Just that if you consider a point source of sound somewhere to your left it will hit your left ear very slightly ahead of your right ear. So perhaps more correct to talk in terms of time delay than phase. There will also be a slight amplitude difference between the two ears as well to further localise the source of the sound.

A simple stereo pair of microphones slung in front of a group of musicians for example will capture both amplitude difference and time delay information which will be recorded and reproduced by the loudspeakers.

But if you are mixing a load of single mics or other audio sources down to stereo the positional information in the stereo mix is entirely amplitude based. Any time delays the listener perceives are a product of hearing sound from two loudspeakers with two ears. They are not there in the mix.

time delay is same thing as phase. The sound from any one speaker arrives at left and,right ears with different phases. So mono mikes pan potted tween left and right give positions tween the speakers. Even if the miked sources were in different rooms .......

[mossy2103]

Quote:

Originally Posted by spiney2

u dont go round back of head by panning across front. y not look up my above links as suggsted

At this point I will say this:

1) I bought Dolby Surround and Dolby ProLogic kit years ago when I was upgrading my HiFi and home theatre setup (in the 80's thru the 90's and early 2000's as I recall).

2) Each one, processor, amp or receiver had a MONO surround, as per the Dolby spec, the documentation supplied with each piece of electronics from the likes of Harmon Kardon (an AVP1A, which was a rebadged Fosgate Audionics processor), Yamaha and Denon (an AVD2000 which gave me Dolby Digital capability), and as per the Wiki links provided here.

3) Each one allowed for two rear/surround speakers to be connected, which I did, either using the in-built amps or separate amps fed from the preamp outputs.

4) When playing Dolby Surround and Dolby ProLogic material, the surround channel was heard by myself to be MONO, regardless of kit used, even when using two speakers fed from two outputs. The same MONO signal sent to two speakers. The same MONO sound regardless of processor or receiver used.

5) When using the AVD2000 processor hooked into the same amp setup, I heard Dolby Digital AC3 (as it was called then) for the first time using specific laserdiscs imported from the States that had an AC3 track in place of one of the analogue tracks (played on an imported Pioneer laserdisc player from the States) - and yes, the surrounds instantly changed from mono to discrete stereo.


I now have a Tag McClaren AV32R av processor, feeding what is essentially the same setup, apart from monobloc amps replacing the stereo amps on the main channels (keeping a stereo amp for the rears). Subwoofers and amps upgraded accordingly too. Dolby ProLogic (in its vanilla form with no additional processing) still gives a mono surround channel, albeit from two channels fed by the stereo amp which in turn is fed from the two pre-amp outputs from the AV32R.


Each piece of kit bar a couple had the ability to apply further signal processing (provided by the manufacturer, not Dolby) to the vanilla Dolby output, either by way of additional tweaks or full-blown THX processing.


Now spiney2, can you say that you witnessed the early days of surround sound as I did? Because I heard vanilla Dolby proLogic and Dolby Surround, and the surround was a mono soundfield, even when using two surround speakers fed from two surround outputs.



And I thought that you had decided to stop posting in this thread ........

post 178:

Quote:

I will now stoo responding to the incessant trolls. So unless anyone has a genuine non trolling completely new point to make not already covered ...

[spiney2]

the one and only point im making is, where surround sound exists at all, it is always on the 2.0 version. As for tv broadcasting, where the original mix is 5.1 then downconversion is automatic in the coder, which produces both versions. And maybe some undesirable artifacts as mr andrew suggests.

[spiney2]

Quote:

Originally Posted by mossy2103

At this point I will say this:

1) I bought Dolby Surround and Dolby ProLogic kit years ago when I was upgrading my HiFi and home theatre setup (in the 80's thru the 90's and early 2000's as I recall).

2) Each one, processor, amp or receiver had a MONO surround, as per the Dolby spec, the documentation supplied with each piece of electronics from the likes of Harmon Kardon (an AVP1A, which was a rebadged Fosgate Audionics processor), Yamaha and Denon (an AVD2000 which gave me Dolby Digital capability), and as per the Wiki links provided here.

3) Each one allowed for two rear/surround speakers to be connected, which I did, either using the in-built amps or separate amps fed from the preamp outputs.

4) When playing Dolby Surround and Dolby ProLogic material, the surround channel was heard by myself to be MONO, regardless of kit used, even when using two speakers fed from two outputs. The same MONO signal sent to two speakers. The same MONO sound regardless of processor or receiver used.

5) When using the AVD2000 processor hooked into the same amp setup, I heard Dolby Digital AC3 (as it was called then) for the first time using specific laserdiscs imported from the States that had an AC3 track in place of one of the analogue tracks (played on an imported Pioneer laserdisc player from the States) - and yes, the surrounds instantly changed from mono to discrete stereo.


I now have a Tag McClaren AV32R av processor, feeding what is essentially the same setup, apart from monobloc amps replacing the stereo amps on the main channels (keeping a stereo amp for the rears). Subwoofers and amps upgraded accordingly too. Dolby ProLogic (in its vanilla form with no additional processing) still gives a mono surround channel, albeit from two channels fed by the stereo amp which in turn is fed from the two pre-amp outputs from the AV32R.


Each piece of kit bar a couple had the ability to apply further signal processing (provided by the manufacturer, not Dolby) to the vanilla Dolby output, either by way of additional tweaks or full-blown THX processing.


Now spiney2, can you say that you witnessed the early days of surround sound as I did? Because I heard vanilla Dolby proLogic and Dolby Surround, and the surround was a mono soundfield, even when using two surround speakers fed from two surround outputs.



And I thought that you had decided to stop posting in this thread ........

so you think the inventor of prologic 2, jim fosgate, is wrong and deluded?

[spiney2]

home decoders work differently. Amplitude steering not haas effect. Has anyone counted how often i said this? Now, if there is no position information in the rear channel, then how,does the decoder decide how to amplify or attenuate each rear speaker ? Just a random guess i suppose .......

[mossy2103]

Quote:

Originally Posted by spiney2

so you think the inventor of prologic 2, jim fosgate, is wromg and deluded?

I think that we all agree here that Dolby ProLogic II can provide discrete 5.1 (with stereo surrounds) from 2-channel stereo.

But what you cannot accept from others, and from myself who bought and used the ProLogic kit years ago and to this day is that Dolby ProLogic only provides for a mono surround, albeit the same surround fed to two preamp channels, two amp channels and finally to two speakers.

[mossy2103]

Quote:

Originally Posted by spiney2

home decoders work differently

Erm, we are talking home decoders and home surround formats.

.

Quote:

Amplitude steering not haas effect. Has anyone counted how often i said this? Now, if there is no position information in the rear channel, then how,does the decoder decide how to amplify or attenuate each rear speaker ? Just a random guess i suppose .......

Talking about Dolby Surround and Dolby ProLogic only, the mono surround channel is matrixed into the front channels. The decoder does not amplify or attenuate each rear speaker as the same signal (same frequencies, amplitude, phase etc) is sent to both surround outputs. The respective equipment manufacturer might choose to add in a DSP (Digital Sound processing) chip in order to create additional soundfield effects, but this is at the manufacturer's discretion and is nothing to do with the output from the Dolby chip.

The big step forward was with Dolby Digital AC3 (as it was first known), which probably first appeared on imported NTSC laserdiscs (UK PAL laserdiscs could not carry it at the time, I think that it was due to the lack of analogue tracks that could be sacrificed to have an AC3 track), which did bring non-mono surround channels.

[spiney2]

Quote:

Originally Posted by mossy2103

Erm, we are talking home decoders and home surround formats.

. Talking about Dolby Surround and Dolby ProLogic only, the mono surround channel is matrixed into the front channels. The decoder does not amplify or attenuate each rear speaker as the same signal (same frequencies, amplitude, phase etc) is sent to both surround outputs. The respective equipment manufacturer might choose to add in a DSP (Digital Sound processing) chip in order to create additional soundfield effects, but this is at the manufacturer's discretion and is nothing to do with the output from the Dolby chip.

The big step forward was with Dolby Digital AC3 (as it was first known), which probably first appeared on imported NTSC laserdiscs (UK PAL laserdiscs could not carry it at the time, I think that it was due to the lack of analogue tracks that could be sacrificed to have an AC3 track), which did bring non-mono surround channels.

ac3 is an audio codec. Nothing to do with surround sound.

[mossy2103]

Quote:

Originally Posted by spiney2

ac3 is an audio codec. Nothing to do with surround sound.

Pardon?

AC3 is indeed an audio codec

Quote:

AC3 is a file extension for surround sound audio files used on DVDs format. The AC3 file format was created by Dolby Labs for use in a Dolby Digital audio on DVD, Blu-ray and other digital video formats. AC3 stands for Audio Coding 3.

AC3 increases fidelity over its previous surround sound standard, Pro-logic, with independent tracks for each of the 6 speakers, a 16bit sampling at 48khz rate compressed by 10- 12 times, making for a total bit rate of 384kbps.

To reproduce to the full surround sound signal on an AC3 file requires a supported playback device such as DVD player connected to a Dolby Digital-supporting home theater amplifier. It is more common in computer audio for sound cards to interpret AC3 and put out a PCM stream; however some cards can output a Dolby Digital or DTS stream that may be used on with a home theater amplifier.

http://whatis.techtarget.com/filefor...s-used-on-DVDs


Dolby Digital IS AC3

Dolby Surround IS an audio codec

Dolby Digital (as we now know it) IS an audio codec

All are audio codecs which are closely related with surround sound in that they allow for surround sound to be carried in the datastream

Quote:

A codec encodes a data stream or signal for transmission, storage or encryption, or decodes it for playback or editing.

http://en.wikipedia.org/wiki/Codec


And yet you state that AC3 is nothing to do with surround sound? Well, I can tell you that the first AC3 soundtrack that I heard was Air Force One on NTSC laserdisc - that gave me the first experience of 5.1 surround, where previously I could only experience Dolby ProLogic from NTSC laserdiscs (using the Dolby ProLogic codec)



This thread is just surreal!

[Deacon1972]

Quote:

Originally Posted by spiney2

the earliest home decoders had only 1 rear channel. But since prologic has 2, just using 1 speaker which doesn't give surround sound is rather silly.

Who suggested using only one speaker when two outputs are available?

Dolby Pro Logic uses 'steering logic', basically the dB levels are either raised or lowered depending on dominant sound, ie. Panning front to back, the db levels for the front channels get lowered as the rears increase, this gives the illusion of audio going over head. What DPL won't do is position audio to the left or right of the listener using the surrounds - improved placement was only achievable when DD5.1 and DPLII was introduced, where the director or processing could position audio much better in the room by placing discrete information in either the left or right surround channel.

[webbie]

What happened to page 11?