Mono DVD Soundtracks

[Quagmire]

John,

I understand your confussion on this matter. You would be scratching your head if you purchased an audio CD which was labelled "Mono Stereo" because these two terms mean opposite things. "DD 2.0" and "mono" seem to be opposites as well, but all that it really means is that the mono track has been recorded discretely on two channels. In theory, you could have a 5.1 mono soundtrack where each one of the channels carries the exact same information - but of course, there is no purpose in that.

If you had your DVD player connected to your receiver via the 6 channel discrete analog inputs, and you then selected that input, you would here the DD 2.0 mono tracks from your left and right front speakers instead of the center speaker. With the digital connection, your receiver is processing this two channel information using Pro Logic processing. Since the left and right tracks are identical, there is no difference betweeen them, the Pro Logic processor is sending all of that information to the center channel speaker. This is how recording engineers/mixers manipulate the signal to place dialog (and other sounds) in the center channel speaker for Pro Logic systems. Pro Logic processing extracts information which is the same in the left and right channels and sends it to the center channel speaker (L + R = C). The processing for the surround channel is just the opposite (L - R = Surrounds). Since there is no difference between the left and right channels of a DD 2.0 mono soundtrack, no information is sent to the surround speakers.

If you want to hear the DD 2.0 mono track from the left and right front speakers, you can change the audio output of your DVD player to "PCM" and set your receiver to stereo rather than Pro Logic. Hope this helps.

Q

[John Beresford]

John,

I understand your confussion on this matter. You would be scratching your head if you purchased an audio CD which was labelled "Mono Stereo" because these two terms mean opposite things. "DD 2.0" and "mono" seem to be opposites as well, but all that it really means is that the mono track has been recorded discretely on two channels. In theory, you could have a 5.1 mono soundtrack where each one of the channels carries the exact same information - but of course, there is no purpose in that.

If you had your DVD player connected to your receiver via the 6 channel discrete analog inputs, and you then selected that input, you would here the DD 2.0 mono tracks from your left and right front speakers instead of the center speaker. With the digital connection, your receiver is processing this two channel information using Pro Logic processing. Since the left and right tracks are identical, there is no difference betweeen them, the Pro Logic processor is sending all of that information to the center channel speaker. This is how recording engineers/mixers manipulate the signal to place dialog (and other sounds) in the center channel speaker for Pro Logic systems. Pro Logic processing extracts information which is the same in the left and right channels and sends it to the center channel speaker (L + R = C). The processing for the surround channel is just the opposite (L - R = Surrounds). Since there is no difference between the left and right channels of a DD 2.0 mono soundtrack, no information is sent to the surround speakers.

If you want to hear the DD 2.0 mono track from the left and right front speakers, you can change the audio output of your DVD player to "PCM" and set your receiver to stereo rather than Pro Logic. Hope this helps.

Q

Q,

I do understand to a point now, and I do understand what you are saying about the two channels being "identical" so therefore it is interpretted by the receiver as one and sends it to the center channel; to a point I understand this. Yet I still dont understand the packaging or marketing behind this---if there are two channels of audio available to begin with, why not offer the DVD in "Dolby Stereo Surround" rather than have two channels of identical audio collapse into a one channel mono experience?

And with regard to your last suggestion, it seems when playing mono soundtrack information, I CAN switch the receiver to STEREO mode without touching the DVD player's output; these mono DVDs will run in stereo mode but to me, they sound worse that way than coming from just the center channel for some reason.

[Quagmire]

John,

You said...

"Yet I still dont understand the packaging or marketing behind this---if there are two channels of audio available to begin with, why not offer the DVD in "Dolby Stereo Surround" rather than have two channels of identical audio collapse into a one channel mono experience?"

This is at the very heart of the issue... there AREN'T two channels of audio available to begin with. The original soundtrack IS a mono track. In order to change it, a remaster would have to be done. It would be great if they remastered all such tracks to at least a Dolby Stereo Surround format as you say, but in many cases they don't. The point is that they are not downgrading a stereo track to a mono track for the DVD release, they are mearly keeping the original mono track intact.

Q

[John Beresford]

John,

You said...

"Yet I still dont understand the packaging or marketing behind this---if there are two channels of audio available to begin with, why not offer the DVD in "Dolby Stereo Surround" rather than have two channels of identical audio collapse into a one channel mono experience?"

This is at the very heart of the issue... there AREN'T two channels of audio available to begin with. The original soundtrack IS a mono track. In order to change it, a remaster would have to be done. It would be great if they remastered all such tracks to at least a Dolby Stereo Surround format as you say, but in many cases they don't. The point is that they are not downgrading a stereo track to a mono track for the DVD release, they are mearly keeping the original mono track intact.

Q

Q:

So then WHY the "2.0" designation if the "original soundtrack IS a mono track" as you say....what am I not getting here? I understand there are no surround elements in the film to decode, hence why there is no "Stereo Surround Mix" or some such rhetoric to play back in PL II; but IF the film is genuine MONO, why does the packaging not say "1.0" as other mono films (like MGM's "Amityville Horror") in my collection do?

[Quagmire]

"but IF the film is genuine MONO, why does the packaging not say "1.0" as other mono films (like MGM's "Amityville Horror") in my collection do?"

Because they have placed the mono track on two discrete channels; in this case the front left and right channels. In the example you used, "Amityville Horror" they chose to place the mono track on only one channel, probably the center channel.

Think of it like this... in days of old, if you went to a movie which was presented with a mono soundtrack, that didn't mean that there was only one speaker in the auditorium. The soundtrack may have been produced through two or more speakers even though it was only a mono track. Even though the track was mono, it may have been more easily heard by the entire audience when reproduced on multiple speakers. The same rationale may have gone into the decision to place the mono track on the front two channels of the DVD rather than on just the center channel. Regardless of how many channels it is played on, the track remains mono: Like I said in an earlier post, in theory you could have a 5.1 mono soundtrack but I doubt anyone would feel that there was any logical reason to do so. At least with a 2.0 mono track, it can be heard properly by those who own only a two channel stereo system as opposed to a full surround sound system. There have been many such mono recordings over the years which were made for playback on two channel systems - the format didn't find its beginning with the advent of DVD or Dolby Digital.

Q

[John Beresford]

Alright, Q...when you say this:

"Regardless of how many channels it is played on, the track remains mono: Like I said in an earlier post, in theory you could have a 5.1 mono soundtrack but I doubt anyone would feel that there was any logical reason to do so. At least with a 2.0 mono track, it can be heard properly by those who own only a two channel stereo system as opposed to a full surround sound system."


I understand what you are saying----like, the overall SIGNAL is MONO, and therefore it doesnt matter how many CHANNELS are playing the thing, it's still a MONO SOUND...much like the theory behind ALL CHANNEL STEREO mode on a receiver; although called stereo, you're actually just hearing ONE SIGNAL through each speaker, correct?

Now, while I can understand that, what do you mean that with a 2.0 mono track, it can be heard properly by those who own a two channel system? Are you saying that those folks with two channels in their stereo system can playback this disc and have it come from the two stereo channels (but in mono), but because in MY system, because I have a full 5.1 system and digital connection with a Pro Logic II decoder defaulting right away automatically, the receiver is collapsing the mono signal and sending it into the center channel only? Would this be why I can ONLY play these mono soundtracks through the center channel or through 2-channel stereo only?

[kelsci]

John; on your remote control to your Onkyo, do you have a buttom marked "stereo"? My Sherwood has that button. If I play a VHS Hi-Fi mono tape, that tape will have a mono soundtrack on the left and right hi-fi tracks(as well as a single mono track on the linear track). Therefore you have 2.0 analogue FM soundtracks. I have a Laserdisc Republic serial that has a mono recording on the left and right FM analogue tracks(call this 2.0 FM analogue soundtracks) as well as the left and right digital tracks(call this 2.0 16 bit digital tracks). These two machines are connected to two separate analogue inputs on the Sherwood(tape and aux). If I hit stereo on the Sherwood, the left mono track plays out of the left speaker; the right mono track plays out of the right speaker. You now have two independent 2 channel mono sound. Keep this in mind too. The audio from both the above machines are hooked up to the left and right analogue inputs.

Now we have a DVD player with a disc labled 2.0 dolby digital mono. This player is connected to the Sherwoods DVD analogue inputs. There is no PHYSICAL difference occuring as to these hookups of all three machines. Even if you outputted the 2.0 mono dvd through the coax or optical cable from the player, the receiver would still ouput two independent mono tracks.

The only way you would hear a non-mono sound from any of the above is if the receiver has a DSP usually called MONO MOVIE. It is a circuit that is a kind of "splitter" to create a "difference" in the sound on one or both of the channels. When a "difference" occurs, the receiver would then give you five channels from a mono source..

I think the answer to your mono question whether it be D.D. 1.0 or 2.0 steered to the center channel when the receiver is in DPL mode is DIFFERENCE and PHASING. Since the samples above have no difference or phasing(proof of that is listening the examples above; the audio is heard only between the speakers on your tv screen) the DPL chip recognizes the sound as sound that should be placed in the center and as such, in DPL we have the center channel speaker. 'Hope maybe this helps.

[Quagmire]

Are you saying that those folks with two channels in their stereo system can playback this disc and have it come from the two stereo channels (but in mono), but because in MY system, because I have a full 5.1 system and digital connection with a Pro Logic II decoder defaulting right away automatically, the receiver is collapsing the mono signal and sending it into the center channel only? Would this be why I can ONLY play these mono soundtracks through the center channel or through 2-channel stereo only?

Yes.

Q