Two channel audio can contain surround information if specifically encoded from a multi channel master mix that contains the surround as discrete channels. The LCRS or 5.1 channels are then passed through an encoder which produces a two channel mix that a complementary decoder can process to derive a close approximation of the original discrete source channels.
If you simply sum the rear surround channels with the front channels, without any of the phase shifting that Dolby encoding uses, the result is not a surround mix as you lose the ability to separate out the two channels again.
If the original sound mix was direct to stereo then there is no surround information present by intent.
So it depends on how the two channel audio is created. If encoded from a discrete surround master then it will have surround information deliberately included.
I still do not see what you are getting at. Yes, you can downmix from 5.1 to 2.0, as happens "in real time" for sd television. But if you simply mixed in the 2.0 rear channels without phase coding, the result would be an unusable mess.
I still do not see what you are getting at. Yes, you can downmix from 5.1 to 2.0, as happens "in real time" for sd television. But if you simply mixed in the 2.0 rear channels without phase coding, the result would be an unusable mess.
What is so difficult?
If you start out with a multi channel surround mix you can encode it into two channels to produce a mix that can be decoded back out to a close approximation of the original multichannel mix.
If you mix that multichannel source down to stereo with out any of the phase processing that Dolby encoding uses you do not get a mix that can be decoded easily to resemble the original multichannel mix.
If you create a two channel mix directly then there is no surround information to decode.
If you mix the front and rear channels you do not get an unusable mess. All that happens is the sound that would be in the rear channels comes out of the front speakers. It would be no more of a mess than summing left and right stereo into a single speaker.
.... presumaby, the difficulty of reading a digital datastream from a 35mm film going through a shutter gate mechanism is one more reason why it is now obsolete !
No that was usually not a problem although severe scratching and printing errors could be, the world has gone digital and most multiplexes cannot now show 35mm prints although some independents can.
With regard to 2 channel mix down, surround/stereo mix down is a menu option on some equipment especially older Sony DVD players.
You do realise you have to create the Dolby surround soundtrack to begin with?
Once it is created you can then encode it on to a stereo soundtrack, to hear it back you need to decode it using DPL.
If the is no Dolby surround soundtrack encoded, then there is no information to decode.
But as you may know, if you apply DPL to any vanilla stereo soundtrack ie. stereo CD, most av amps will give you some sort of surround sound, not always good in some cases, what you hear won't be anything that has been encoded onto the original soundtrack, it simply converts the stereo soundtrack to 5.1 using broadband logic steering.
Similar to DPL is DTS Neo 6, using multiband logic sterring it can take stereo and convert it to 5.1 or 6.1 but in a 7.1 configuration, DTS Neo X can take stereo, 5.1, 6.1 and 7.1 and convert it to 11.1. Surely you wouldn't say all these format are all encoded onto the original soundtrack first before having to be decoded?
You do realise you have to create the Dolby surround soundtrack to begin with?
Once it is created you can then encode it on to a stereo soundtrack, to hear it back you need to decode it using DPL.
If the is no Dolby surround soundtrack encoded, then there is no information to decode.
But as you may know, if you apply DPL to any vanilla stereo soundtrack ie. stereo CD, most av amps will give you some sort of surround sound, not always good in some cases, what you hear won't be anything that has been encoded onto the original soundtrack, it simply converts the stereo soundtrack to 5.1 using broadband logic steering.
Similar to DPL is DTS Neo 6, using multiband logic sterring it can take stereo and convert it to 5.1 or 6.1 but in a 7.1 configuration, DTS Neo X can take stereo, 5.1, 6.1 and 7.1 and convert it to 11.1. Surely you wouldn't say all these format are all encoded onto the original soundtrack first before having to be decoded?
essentially, any 2.0 out-of-phase component is treated as "surround". Which is how soundbars work, ie, left is inverted, attenuated, added to right, and appears "beyond" the right speaker (and vice versa). Of course, there will always be a small "out of phase" component on all sound recordings, depending on mikes used, and how mixed. But this is usually small and insignificant. Although you can "crank it up" on a matrix surround decoder .......... but much "stereo" is in fact recorded as surround anyway .......
If you start out with a multi channel surround mix you can encode it into two channels to produce a mix that can be decoded back out to a close approximation of the original multichannel mix.
If you mix that multichannel source down to stereo with out any of the phase processing that Dolby encoding uses you do not get a mix that can be decoded easily to resemble the original multichannel mix.
If you create a two channel mix directly then there is no surround information to decode.
If you mix the front and rear channels you do not get an unusable mess. All that happens is the sound that would be in the rear channels comes out of the front speakers. It would be no more of a mess than summing left and right stereo into a single speaker.
Yes, if you deliberately mix several single channel sources together, then that is mono (by definition)! But we are talking surround sound ......... I may be unusually thick, but I still don't understand what point you are making.
..... what would be the point of mixing in the intended surround sound, but missing out the phase coding necessary for surround? That was my point. Yes ok, it would be mono. But like you say, it's then not re-separable.
You do realise you have to create the Dolby surround soundtrack to begin with?
Once it is created you can then encode it on to a stereo soundtrack, to hear it back you need to decode it using DPL.
If the is no Dolby surround soundtrack encoded, then there is no information to decode.
But as you may know, if you apply DPL to any vanilla stereo soundtrack ie. stereo CD, most av amps will give you some sort of surround sound, not always good in some cases, what you hear won't be anything that has been encoded onto the original soundtrack, it simply converts the stereo soundtrack to 5.1 using broadband logic steering.
Similar to DPL is DTS Neo 6, using multiband logic sterring it can take stereo and convert it to 5.1 or 6.1 but in a 7.1 configuration, DTS Neo X can take stereo, 5.1, 6.1 and 7.1 and convert it to 11.1. Surely you wouldn't say all these format are all encoded onto the original soundtrack first before having to be decoded?
before digital, when only 2.0 was available, then mixing would have been on that system! Now, it is on 5.1, 7.1, atmos, whatever the heck. So mixed in the "highest up format used", and automatically matrixed down to less complex formats. But technicians are supposed to spot-check compatibility, down to and including the original 2.0
As far as I know, the Sony version treats surround sound identically, since there is only one sort of cinema speaker system. Or is the surround mix significantly different? I don't see how it possibly can be, since nobody is going to 2 sound mixes, completely differently. Patents apply to the specific audio codecs, and coding system used, but not to the surround principle itself (which is back to Scheiber, and patents now expired). Although Dolby has I think specifically patented "7.1, 9.1 ......." etc .......
It's a minor point, but in film and TV production the final multichannel mix isn't encoded in to DD, DTS, Dolby Surround, or any of the HD audio formats until a master for that format is created. Up to that point the sound track might exist either as an edit file with multichannel source streams, or possibly a simple multichannel mix that reflects what might appear on DVD/Blu-ray but in PCM format.
It's also entirely possible that a master for TV broadcast will have a different mix and encoding to a master used to burn DVDS which itself will be different to the Blu-ray master.
It's a minor point, but in film and TV production the final multichannel mix isn't encoded in to DD, DTS, Dolby Surround, or any of the HD audio formats until a master for that format is created. Up to that point the sound track might exist either as an edit file with multichannel source streams, or possibly a simple multichannel mix that reflects what might appear on DVD/Blu-ray but in PCM format.
It's also entirely possible that a master for TV broadcast will have a different mix and encoding to a master used to burn DVDS which itself will be different to the Blu-ray master.
yes. But given financial constraints, how often might that be done ?
Obviously, as older stuff gets re-released, "remastering" will be used as a selling point. If there is enough incentive, and the original recordings exist, not just the old version soundtrack ........ so you get Rocky Horror Show, with the taped songs re-blended into the original "academy" (non dolby but vastly cleaned up) soundtrack, now digital .........
i'm watching star trek repeats on cbs action ...... the letterbox format, digitised picture from 35mm, new sound mix (which wrecks the intro), and new digital effects, are all rather incongruous and detract somewhat from the actual stories ........
Ive just looked up "virtual surround", ie, soundbars, and they use additional techniques to the "wide stereo" I described above (and remember from the 70s). With comb filters, other tricks, etc ...... now that there are specific d.s.p. chips specially for real-time audio processing and suchlike ........
yes. But given financial constraints, how often might that be done ?
Very regularly. TV companies don't play the DVD or Blu-ray for broadcast. Films are often edited for broadcast to comply with the watershed requirements and to accommodate advertising breaks on commercial channels. There are also local considerations (religion etc)
..... I remember the Glen Miller Story getting rereleased, after they found the tapes ...... there was the original soundtrack, then a sudden hiss as the newly found band recording was spliced in ........ presumably it would be done more subtly now .....
Very regularly. TV companies don't play the DVD or Blu-ray for broadcast. Films are often edited for broadcast to comply with the watershed requirements and to accommodate advertising breaks on commercial channels. There are also local considerations (religion etc)
Yes films are de-sexed and de-f*cked for tv, but, a different sound mix ?
It's a minor point, but in film and TV production the final multichannel mix isn't encoded in to DD, DTS, Dolby Surround, or any of the HD audio formats until a master for that format is created. Up to that point the sound track might exist either as an edit file with multichannel source streams, or possibly a simple multichannel mix that reflects what might appear on DVD/Blu-ray but in PCM format.
It's also entirely possible that a master for TV broadcast will have a different mix and encoding to a master used to burn DVDS which itself will be different to the Blu-ray master.
That is correct, sometimes the broadcast version has a different dynamic range for example to improve compatibility with commercial breaks.
Yes films are de-sexed and de-f*cked for tv, but, a different sound mix ?
I'm not talking about a complete head-to-toe reworking including ADR and foley effects... But I am saying that it is wrong to assume that what's on the DVD/Blu-ray somehow represents the only mix that exists for a certain film or TV project.
Films and TV series are marketed world wide. However, not all world markets will take the production in the same presentation. Even within a single sales territory there are vertical markets that will require different treatments of the material.
i think wot chrisjr means is, downmixing from 5.1 to 2.0 is neither lossless nor reversible, in that going back the other way will a best give a bad copy .....
i think wot chrisjr means is, downmixing from 5.1 to 2.0 is neither lossless nor reversible, in that going back the other way will a best give a bad copy .....
How many more times does it need explaining?
A two channel sound track will only contain surround sound information if deliberately encoded from a discrete multi channel master mix in such away as to allow a complimentary decoder to separate out the original channels. This process is not lossless as the decoded channels will not be 100% identical to the original source channels. So in that sense precise positional information has been lost to a certain extent. But they will be pretty close, close enough to give a good enough surround effect for most situations. So it is lossy but it is (imperfectly) reversible.
If the two channel sound track is not encoded from a multi channel master mix, or any such master is not encoded specifically but the channels are simply summed together, then any surround information it contains is entirely accidental and it is anyone's guess what a decoder will do with it. So that scenario is both lossy and irreversible. In that the original surround mix has been lost and cannot be reversed back to any sort of facsimile of the original.
All this stuff about Dolby surround is nothing new. Where Spiney 2 went wrong was when he said (in a different thread) that dolby digital was matrixed.
i think wot chrisjr means is, downmixing from 5.1 to 2.0 is neither lossless nor reversible, in that going back the other way will a best give a bad copy .....
They don't mean that at all.....
How can you decode surround sound information on a stereo soundtrack when that information has not been encoded on to the stereo soundtrack in the first place, unless you are saying there are no exceptions and Dolby surround is present on all stereo soundtracks.
You do realise a DPL decoder can decode and create soundtracks. It will decode Dolby surround information when encoded or present on a stereo soundtrack, it will also convert plain stereo to 5.1 by using digital processing (broadband logic steering), basically its fake, not that different to the jazz, pop, disco, church DSP's you find on some av receivers.
Exactly. As I try to explain over and over again. I'm not sure if spinney2 really does find it hard to understand what I have written, I've not made myself sufficiently clear or he is just trolling for the hell of it.
How can you decode surround sound information on a stereo soundtrack when that information has not been encoded on to the stereo soundtrack in the first place, unless you are saying there are no exceptions and Dolby surround is present on all stereo soundtracks.
Well he has posted on more than one occasion that 2.0 is surround without qualifying it by saying 'if Dolby encoded" or similar. So who knows?
You do realise a DPL decoder can decode and create soundtracks. It will decode Dolby surround information when encoded or present on a stereo soundtrack, it will also convert plain stereo to 5.1 by using digital processing (broadband logic steering), basically its fake, not that different to the jazz, pop, disco, church DSP's you find on some av receivers.
That is something people who don't understand the core technology have difficulty getting their heads round. Just because some noise comes out of the rear speakers it does not mean that the sound track they are listening to is actually surround sound to begin with.
Bit like thinking that Dave on Freeview is HD just because the letters H and D were printed alongside each other on the box your telly came in.
Comments
https://www.youtube.com/watch?v=mypS7VfwZLI
I still do not see what you are getting at. Yes, you can downmix from 5.1 to 2.0, as happens "in real time" for sd television. But if you simply mixed in the 2.0 rear channels without phase coding, the result would be an unusable mess.
If you start out with a multi channel surround mix you can encode it into two channels to produce a mix that can be decoded back out to a close approximation of the original multichannel mix.
If you mix that multichannel source down to stereo with out any of the phase processing that Dolby encoding uses you do not get a mix that can be decoded easily to resemble the original multichannel mix.
If you create a two channel mix directly then there is no surround information to decode.
If you mix the front and rear channels you do not get an unusable mess. All that happens is the sound that would be in the rear channels comes out of the front speakers. It would be no more of a mess than summing left and right stereo into a single speaker.
No that was usually not a problem although severe scratching and printing errors could be, the world has gone digital and most multiplexes cannot now show 35mm prints although some independents can.
With regard to 2 channel mix down, surround/stereo mix down is a menu option on some equipment especially older Sony DVD players.
You do realise you have to create the Dolby surround soundtrack to begin with?
Once it is created you can then encode it on to a stereo soundtrack, to hear it back you need to decode it using DPL.
If the is no Dolby surround soundtrack encoded, then there is no information to decode.
But as you may know, if you apply DPL to any vanilla stereo soundtrack ie. stereo CD, most av amps will give you some sort of surround sound, not always good in some cases, what you hear won't be anything that has been encoded onto the original soundtrack, it simply converts the stereo soundtrack to 5.1 using broadband logic steering.
Similar to DPL is DTS Neo 6, using multiband logic sterring it can take stereo and convert it to 5.1 or 6.1 but in a 7.1 configuration, DTS Neo X can take stereo, 5.1, 6.1 and 7.1 and convert it to 11.1. Surely you wouldn't say all these format are all encoded onto the original soundtrack first before having to be decoded?
essentially, any 2.0 out-of-phase component is treated as "surround". Which is how soundbars work, ie, left is inverted, attenuated, added to right, and appears "beyond" the right speaker (and vice versa). Of course, there will always be a small "out of phase" component on all sound recordings, depending on mikes used, and how mixed. But this is usually small and insignificant. Although you can "crank it up" on a matrix surround decoder .......... but much "stereo" is in fact recorded as surround anyway .......
Yes, if you deliberately mix several single channel sources together, then that is mono (by definition)! But we are talking surround sound ......... I may be unusually thick, but I still don't understand what point you are making.
..... what would be the point of mixing in the intended surround sound, but missing out the phase coding necessary for surround? That was my point. Yes ok, it would be mono. But like you say, it's then not re-separable.
before digital, when only 2.0 was available, then mixing would have been on that system! Now, it is on 5.1, 7.1, atmos, whatever the heck. So mixed in the "highest up format used", and automatically matrixed down to less complex formats. But technicians are supposed to spot-check compatibility, down to and including the original 2.0
As far as I know, the Sony version treats surround sound identically, since there is only one sort of cinema speaker system. Or is the surround mix significantly different? I don't see how it possibly can be, since nobody is going to 2 sound mixes, completely differently. Patents apply to the specific audio codecs, and coding system used, but not to the surround principle itself (which is back to Scheiber, and patents now expired). Although Dolby has I think specifically patented "7.1, 9.1 ......." etc .......
It's also entirely possible that a master for TV broadcast will have a different mix and encoding to a master used to burn DVDS which itself will be different to the Blu-ray master.
yes. But given financial constraints, how often might that be done ?
Very regularly. TV companies don't play the DVD or Blu-ray for broadcast. Films are often edited for broadcast to comply with the watershed requirements and to accommodate advertising breaks on commercial channels. There are also local considerations (religion etc)
http://www.nytimes.com/1984/11/17/movies/universal-to-reissue-glenn-miller-story.html
Yes films are de-sexed and de-f*cked for tv, but, a different sound mix ?
That is correct, sometimes the broadcast version has a different dynamic range for example to improve compatibility with commercial breaks.
Films and TV series are marketed world wide. However, not all world markets will take the production in the same presentation. Even within a single sales territory there are vertical markets that will require different treatments of the material.
possibly. I dont watch commercial tv much, but the ads are always ridiculously compressed compared with any programmes
How many more times does it need explaining?
A two channel sound track will only contain surround sound information if deliberately encoded from a discrete multi channel master mix in such away as to allow a complimentary decoder to separate out the original channels. This process is not lossless as the decoded channels will not be 100% identical to the original source channels. So in that sense precise positional information has been lost to a certain extent. But they will be pretty close, close enough to give a good enough surround effect for most situations. So it is lossy but it is (imperfectly) reversible.
If the two channel sound track is not encoded from a multi channel master mix, or any such master is not encoded specifically but the channels are simply summed together, then any surround information it contains is entirely accidental and it is anyone's guess what a decoder will do with it. So that scenario is both lossy and irreversible. In that the original surround mix has been lost and cannot be reversed back to any sort of facsimile of the original.
They don't mean that at all.....
How can you decode surround sound information on a stereo soundtrack when that information has not been encoded on to the stereo soundtrack in the first place, unless you are saying there are no exceptions and Dolby surround is present on all stereo soundtracks.
You do realise a DPL decoder can decode and create soundtracks. It will decode Dolby surround information when encoded or present on a stereo soundtrack, it will also convert plain stereo to 5.1 by using digital processing (broadband logic steering), basically its fake, not that different to the jazz, pop, disco, church DSP's you find on some av receivers.
Well he has posted on more than one occasion that 2.0 is surround without qualifying it by saying 'if Dolby encoded" or similar. So who knows?
That is something people who don't understand the core technology have difficulty getting their heads round. Just because some noise comes out of the rear speakers it does not mean that the sound track they are listening to is actually surround sound to begin with.
Bit like thinking that Dave on Freeview is HD just because the letters H and D were printed alongside each other on the box your telly came in.