Dolby Digital Prologic 2 vs Dolby digital 5.1

Page 2 - Seeking answers? Join the Tom's Guide community: where nearly two million members share solutions and discuss the latest tech.

herolegend

Honorable
Mar 28, 2013
17
0
10,560
What's the differences between them? Using either headset turtle beach capable of digital surround 7.1 and or an actual surround system at home that's capable for a 7.1 surround. What's better for games and movies?
 
Solution


There is no such thing as Dolby Digital Pro Logic, it's Dolby Pro Logic. The reason for this is that Pro Logic is analog, not digital in nature.

Pro Logic is a quadraphonic system in which two additional channels, center and rear, are encoded into the left and right stereo channels. When received by a non Pro Logic receiver, the audio appears to be nothing more than standard stereo audio.

Dolby Digital 5.1 is an encoding and compression scheme. It takes as its input 6 discrete channels, Left, Right, Center, Rear...
We should put that in a sticky. I've wanted to write something like that in this forum for along time but never had the patience. I would have added a section explaining analog a lot more also.

Anyways nice write up.

Happy listening, the Prisoner...
 

Pinhedd

Distinguished
Moderator


Thanks!

If you think that it's sticky-worthy, perhaps you should let the mods know. I'd be happy to clean it up a bit if there's some interest in it.
 
Sorry for bringing up an old thread, but the info that Pinhedd provided would be good for a sticky since so many people are so confused by surround sound formats. So many times I have and others had to keep repeating the same info.

Pinhedd, since you're a mod can't you sticky it?
 

Pinhedd

Distinguished
Moderator


That's a good idea. I'll probably rewrite it and sticky it at some point in the near future. Thanks for the suggestion!
 

Mitch Siegel

Estimable
Jan 11, 2015
1
0
4,510
I have a Pioneer VSX 524 receiver and it chooses the processing automatically based on the audio source coming my Uverse TV receiver. Music seems to be processed via Dolby Pro II, and video channels are processed by Dolby Digital. It doesn't allow me to choose which, it is determined by the input. I am guessing music is stereo source and video is 5.1 source and the Pioneer handles them differently.
 

Pinhedd

Distinguished
Moderator


That's most likely the case.

The music audio arrives as two channel PCM/LPCM (stereo) which is then put through Dolby Pro Logic to expand it if able and then upmixed to the appropriate number of surround channels. The music audio may be sourced from a bitstream that is decoded elsewhere, such as an MP3.

The video audio arrives as a Dolby Digital bitstream which is put through a Dolby Digital decoder to expand it to up to 6 channels. Similarly, it is possible for the Dolby Digital bitstream to be decoded into discrete channels at some point other than the receiver, and then the 6 discrete channels sent to the receiver via multichannel LPCM.
 

skylineivan

Estimable
Mar 25, 2015
4
0
4,510
Pinhedd, you seem to be one of the most knowledgeable contributors on this site so please excuse my ignorance as I am a fresh newbie. However, I have a question that no one can seem to answer. I am hoping you may be able to provide some insight to my limited amount of knowledge?

Are there currently any products (or combination of products) out there that will allow me to play music/audio from a smartphone or tablet (from the 1 headphone jack) and have it sent out to 4 discrete, mono outputs?

What it boils down to is this. I want to produce my album and mix it down to 4 channels (instead of the usual 2). I then want the owner of an iphone or android phone (or even a tablet) to be able to play my multichannel audio from their phone into their 4 speaker setup.

I am looking for an affordable option if that is even possible?

Respectfully,
--Ivan



 

Pinhedd

Distinguished
Moderator
Hi Ivan,

The headphone jack in most smartphones and tablets use a CTIA TRRS signal scheme. There are 4 conductors exposed

Tip - Left audio

Ring 1 - Right audio

Ring 2 - reference (ground)

Sleeve - Microphone

The DAC on the audio codec has limited bandwidth as it's designed to produce baseband analogue signals that are within the audible frequency range (usually 10hz - 24,000hz). Ergo, few (if any) phones/tablets will be capable of generating multiple discrete audio channels on the same wire using RF modulation as they simply don't have the bandwidth needed to do so. This is why Dolby Pro Logic and Dolby Pro Logic II are used. They allow four or six channels to be approximately encoded into two channels.

You as a producer can record your audio in four or six channels and then pass it through a Dolby Pro Logic or Dolby Pro Logic II encoder to derive two channels. If these two channels are not decoded, they will sound similar to the original two front channels. If they are decoded, the approximated surround channels will be recovered. The phone/tablet do not need to feature any Dolby technology for this to work, but the user does need to have a Dolby Pro Logic or Dolby Pro Logic II decoder between the DAC and the speakers. Many gaming headphones support this.

Please keep in mind though that Dolby Pro Logic encoding is not perfect and the channels will not be discrete (although this may not be noticeable). The surround channels in Dolby Pro Logic are band-limited to the range of 100hz to 7Khz, which will not properly capture musical effects or low frequency effects. Dolby Pro Logic II is much better as the surround channels can span 20hz-20,000hz before attenuation occurs. By comparison, Dolby TrueHD (up to 8 discrete channels with lossless encoding) which is used in many BluRay movies has an almost perfectly flat frequency response from 3hz (below audible range) to well over 30,000 hz (above audible range) for each channel which means that it reproduces exactly what was captured.

I would not recommend trying to use Dolby Pro Logic for music, but Dolby Pro Logic II may work.
 

skylineivan

Estimable
Mar 25, 2015
4
0
4,510
Thank you so much for sharing your knowledge. I truly am a newbie but I have a better understanding now. My only other question is this...

you stated, "The phone/tablet do not need to feature any Dolby technology for this to work, but the user does need to have a Dolby Pro Logic or Dolby Pro Logic II decoder between the DAC and the speakers. Many gaming headphones support this."

So, if I were the user. I would need the following?:
Iphone, Dobly Pro Logic Decoder, DAC and speakers. I am assuming that the DAC is part of the amplification process?

I am trying to put together a prototype for a white paper on the benefits of sound for those with autism and I am basically wanting to know what pieces of gear to buy in order to demonstrate this.

I guess it would probably be cheaper to just buy a small DVD/Blu Ray player for the demo but I know that the final content will need to be delivered from a smartphone.
 

Pinhedd

Distinguished
Moderator


The DAC is the part of the phone that converts the raw digital audio samples into analogue waveforms. You'd need a Phone/Tablet, a dolby pro logic II decider, and a set of speakers
 

jdaddabbo

Estimable
Apr 8, 2015
1
0
4,510
You can however (assuming that your specific AVR/Preamp Processor gives you the option to) add Dolby Pro Logic iix post processing on top of Dolby Digital 5.1 in order to output to a 7.1 Channel speaker setup.
 

bowleggedrooster

Estimable
Aug 19, 2015
1
0
4,510
This is directed at skylineivan but I am hopping that pinhead will answer some of my questions.
Ok let me give you a heads up on recording music I have been playing music since i was 10 learning trombone in grade school at the same time my uncle pulled me to the side and taught me guitar were i was pushed to the 4 string bass at family get togethers because I could read bass lines of music because i played trombone in school were the others in the family could only read treble clef.Anyway since then and the way I was taught I came out of high school with scholarships and a well rounded musician! But I did something stupid like most teenager do I didn't take the scholarship packed my little S-10 up and hit the road playing in countless bands all my life because I could fill in hole that was missing in a band I had no problem playing every thursday friday and saturday night making $100 a night and having a party all my life.

I said all that to give you an idea of were I'm coming from as far as your questions about recording and playing back audio ( well i should say "music") because here is the thing skylineivan. For Hollywood 5.1 Dolby Surround Sound
was created and took sound to a whole new level as far as sound effects in a movie theater all to sell tickets before you could even buy a Sony Surround Sound receiver at Walmart you could only get that kind of sound quality only in a movie theater besides system was way to expensive for home use and Hollywood or the Box Office was losing profits due to home movie rentals at that time everyone waited until the movie came out on VCR tape Yea I said VCR and tape! LOL!
But here is were I think the Music Companies made a huge mistake they did not team up with Hollywood and upgrade there format to Dolby 5.1 And to this day like pinhead was getting at we still are buying music now in the Left/Right 2 channel stereo format!!!!!!!??????????
A format that is at least a 100 yrs old when music went from AM mono to FM stereo And to make things worse when the internet came in the 90's and we quit buying are music from a music store and started downloaded songs for FREE to a CD on a PC and in order to do this you have to through allot of the music data in the trash so it will be small enough to send over the internet you have to compress it into a .mp3 file you really are cutting out any and everything that can be thrown in the trash and the first to go is the low Hz(the bass) then all the SIZZLE SPARKLE and I tend to think all of the FEELING in the song is really cut out of the recording ( this is the stuff that the Performer spent hours of his time in the studio getting it recorded just right sometimes playing the same song over and over all day and at times many days getting it to the highest sound quality that he feels is the best that he can produce and after all that you tear it apart strip it down and compress it into a small package just so it can be sent to anybody on the web for free but it sounds like a piece of shit (Oh thanks for the free Shitty version of Stairway To Heaven) But if you had bought the CD from a music store it would be a very different sounding recording but you can't tell because you never had it in the first place?
Now the Music Companies threw a fit cuz nobody is buying there records at Walmart anymore so the internet killed the "Fat Man" (the Producer in the music world) see there are three Ps in music. The Performer (me) The Publisher (the factory which makes the cases of albums for a set price) and The Producer (the Fat Man which fronts all the money to make it all happen) and also makes all the money by the way!! The Publisher and the Performer has been getting screwed from the start in the game from Elvis to Garth Brooks by the Fat Man (RCA Atlantic Records ect..) but as time went on the Performer wised up and started Produced his own albums when he could rake up enough money to do so. Thats why I brought up Garth he had been told and warned before he went to Nashvile not to sign any contracts with the Fat Man!! So he was one of the smart ones that made sure the Fat Man didn't screw him up on sex drugs and rock n roll he had a plan he only put two of his own songs on his first LP the others were written by other song writers he only sung them. "Two of a Kind" and "The Dance" were picked out of the long list of songs that he had wrote in his notebook that he took to Nashvile he saved the best stuff and tuck those back only giving the Fat Man just two of his own songs! Now when his first LP hit the stores it done ok and made him and the Fat Man some money. But after he got his cut from the first album he took that money and Produced hes second album without the Fat Man Paying only the Publisher for the cases of CDs that he sold and he SOLD A LOT OF CDs my friend this album was No Fences which had 4 #1 hits and 4 top 10 hits and it sold more copies than any other singer song writer Album in history selling more LP copies than Elvis the Beatles the only album that sold more than No Fences was Michael Jackson's "Thriller"!
Just a little bit of music trivia there? But back to "THE DAY THE MUSIC DIED"
We don't buy music anymore we download a bad copy of the highest format that the studio can produce thats why I think you can get 96Khz and 192Khz sample rates even tho the ear can't hear that its any better its the mixing engineer that knows this is going to be compressed into a mp3 latter on down the chain to his listener and he is adjusting for that in a funny kind of way?
Now my point to pinhead is this?

If I mix down all the tracks to a 6 channel format with all the signals assigned to there assigned speaker in a 6 channel analog final mix if I run it threw an encoder it will be compressed and may or may not be replayed on what ever system my listener chooses to use just as I intended for the mix to sound like? Will I have a better chance getting my mix to the listeners ear leaving it in a huge 6 channel analog or maybe a 3 channel S/PDIF format using 3 optical connections I'm just reaching for answers I do agree that a set format and standard connectors be reached in order to allow the mixing engineer to create the sound image that will be recreated on at least a 7.1 system using at least optical connections and get away from wires altogether.

On another point I also think that converting the audio from analog to digital back to analog back to digital then only to end as an analog signal for the speakers is a problem too!
Either the speakers need to have digital inputs or the mics and guitars needs to have A/D chips right at the diaphragm and pickup cuz the signal needs to convert to digital and stay digital putting our analog mixers in the closet and work only with digital having D/As only in the speaker cabinet? Just a thought? Because the rate we are going having a Smart PC mixing engineer instead of a DAW is not to far away! Have the PC log all sounds via frequency imaging were it learns what a cell phone ringing looks like in the wave form and takes it out without even asking or maybe a popup would be in order stuff like 60Hz hum or even as far as all white noise? Oh its coming and its coming fast!!

Last thing I am currently working on music in the 7.1 format there are no rules or wrong ways of doing this were should certain voices be placed in the surround sound 3D image were all and everything can be placed and moved at anyplace at anytime? Do we separate or surround and blend with chorus and delay? Music has never been in this format other than Live concerts on DVD and Movie Soundtracks we need to learn that there is 4 and sometimes 6 other speakers that we never have even thought of using music needs to take advantage of this like Hollywood has done so well!!
 

Dave L 100

Commendable
Feb 15, 2016
1
0
1,510
After hours watching the same movie once in, Dolby Pro Logic and then in Neo-6 Cinema, a couple of trusted friends finally came up with the answer, I'm talking about my ears. I should tell you what receiver I am using, Denon AVR-2807. The Dolby Pro Logic-2, filled the room much better than NEO-6 , I think ProLogic-2 gave me a better theater experience. In my case the ProLogic works for me, it's coming from two sources, first of all HD 5.1 from my cable provider. And of course the second source would be my Blu-ray player. So that wraps it up for me, my receiver is permanently set, to decode on Dolby Pro logic 2.