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LPCM vs.Dolby TrueHD vs. DTS-HD Master Audio - Page 3

Poll Results: LPCM vs. Dolby TrueHD vs. DTS-HD Master Audio

 
  • 17% (4)
    LPCM
  • 39% (9)
    Dolby TrueHD
  • 43% (10)
    DTS-HD Master Audio
23 Total Votes  
post #61 of 81
2/3/13 at 8:16am
Quote:
Originally Posted by PlayNice View Post

Not trolling just asking a simple question, everyone here says they are the same "but"... If they were the same why is there a "but".

They all sound the same but they may come in at different volume levels which can make them sound different until levels are matched precisely. So in one sense they are the same and in another they aren't the same. The "but" is there to make that distinction. Surely, this isn't complicated to understand.
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post #62 of 81
2/3/13 at 1:20pm
P(ayNice asked the question and clearly does not like the answers he gets, no matter how many of us say there's no difference, and no matter how many different ways we try to explain why that's the case. PlayNice has only made one substantive contribution here, that the Big Screen edition of Revenge of the Fallen doesn't sound as good as the other release. Both are dts-MA and dialn orm is the reason for the difference, an explanation that PlayNice also doesn't seem to like. I suspect nothing will answer the question to his satisfaction since he believes there's a difference and all of the substantive answers here do not support that belief.
(duplicate post deleted smile.gif)
Edited by BIslander - 2/3/13 at 5:57pm
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post #63 of 81
2/3/13 at 4:31pm
I agree, BIslander. So much so that your post was worth reading twice. wink.gif
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post #64 of 81
2/3/13 at 4:35pm
Quote:
Originally Posted by CruelInventions View Post

They all sound the same but they may come in at different volume levels which can make them sound different until levels are matched precisely. So in one sense they are the same and in another they aren't the same. The "but" is there to make that distinction. Surely, this isn't complicated to understand.

I think some people claim to understand what lossless audio means without having the foggiest idea that file compression algorithms have absolutely no bearing on the sound's remaining lossless. That appears to be the case here.
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post #65 of 81
2/3/13 at 8:55pm
Maybe that's it. If not, then BIslander's post is the maybe that's it. wink.gif
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post #66 of 81
2/4/13 at 12:37pm
Thread Starter 


One last thing this table shows each format has a varying bit rate, so if that's the case lossless or not LPCM would give the better audio.

I think what everyone here is failing to understand Lossless means what ever data is compressed is at the end decompressed with no data lost. That said LPCM can take the highest quality in and out then DT-HD Master Audio then Dolby TrueHD.

Lossless is lossless but it's the content in that makes the difference and looks to me that LPCM is able to offer the best sound in and out.
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post #67 of 81
2/4/13 at 12:54pm
PlayNice - It seems pretty clear you don't understand how home entertainment audio works. Movies are mastered as multichannel PCM and audio systems process PCM to produce sound. PCM soundtracks take up a lot of space and studios use compression codecs to reduce the size. Lossless codecs such as TrueHD and dts-MA remove some data in the encoding step and restore every bit of data that they removed in the decoding step.

By definition, PCM = decoded TrueHD = decoded dts-MA. If the source is the same, then all three produce bit for bit identical PCM.

btw, lossless refers to a type of data compression. PCM is not compressed. So, it is not correct to call PCM lossless. Usually, that distinction doesn't matter. But, in the context of this discussion, it does.


As for the chart, lossless codecs use variable bitrates, taking whatever bandwidth they need at any given moment. PCM rates are fixed, meaning silence occupies the same bandwidth as the most active parts of a soundtrack. There's no point in comparing those numbers.
Edited by BIslander - 2/4/13 at 1:01pm
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post #68 of 81
2/4/13 at 2:20pm
Quote:
Originally Posted by BIslander View Post

PlayNice - It seems pretty is totally clear you don't understand how home entertainment audio works....

Let me help you. biggrin.gif
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post #69 of 81
2/4/13 at 3:07pm
Quote:
Originally Posted by mtbdudex View Post

This thread could take a life of its own, like the cable thread or the amp thread....is it necessary ......

Your insight is proving very keen, sir.
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post #70 of 81
2/4/13 at 3:29pm
Thread Starter 
Quote:
Originally Posted by William View Post

Let me help you. biggrin.gif

Quote:
Originally Posted by BIslander View Post

PlayNice - It seems pretty clear you don't understand how home entertainment audio works. Movies are mastered as multichannel PCM and audio systems process PCM to produce sound. PCM soundtracks take up a lot of space and studios use compression codecs to reduce the size. Lossless codecs such as TrueHD and dts-MA remove some data in the encoding step and restore every bit of data that they removed in the decoding step.

By definition, PCM = decoded TrueHD = decoded dts-MA. If the source is the same, then all three produce bit for bit identical PCM.

btw, lossless refers to a type of data compression. PCM is not compressed. So, it is not correct to call PCM lossless. Usually, that distinction doesn't matter. But, in the context of this discussion, it does.


As for the chart, lossless codecs use variable bitrates, taking whatever bandwidth they need at any given moment. PCM rates are fixed, meaning silence occupies the same bandwidth as the most active parts of a soundtrack. There's no point in comparing those numbers.

I find it funny how you are trying to state I do not know in a way to put down my intelligence. Yes I don't know that's why I started this thread, to learn and I enjoy learning so forgive me if I do not take your word as gospel and I do a little research of my own.

So thank you for pointing out LPCM is not compressed but the other options are so if that is the fact then DTS would be the winner in compression, variable bit rates and all cause out I'd Dolby and DTS It looks to me DTS has the higher potential bit rate. Would I be wrong in saying that?

I say this cause you say if the source material is the same they will produce the same PCM, well if you had a soundtrack of let say 21.5Mbps average variable bit rate how would you cram that into a Dolby TrueHD codec with an average bit rate maximum of 18Mbps?
Edited by PlayNice - 2/4/13 at 4:23pm
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post #71 of 81
2/4/13 at 3:37pm
This continues to be amusing.
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post #72 of 81
2/4/13 at 4:00pm
Not your intelligence. Your attitude. You don't appear to be in search of information. Rather, you want to argue about things you don't understand.

I have tried to explain some basic principles and the more arcane subject of dialog normalization. But , that appears to be a waste of time, both yours and mine.
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post #73 of 81
2/4/13 at 4:13pm
Quote:
Originally Posted by PlayNice View Post


I find it funny how you are trying to state I do not know in a way to put down my intelligence. Yes I don't know that's why I started this thread, to learn and I enjoy learning so forgive me if I do not take your word as gospel and I do a little research of my own.

So thank you for pointing out LPCM is. To compressed but the other options are so if that is the fact then DTS would be the winner in compression, variable bit rates and all cause out I'd Dolby and DTS It looks to me DTS has the higher potential bit rate. Would I be wrong in saying that?

I say this cause you say if the source material is the same they will produce the same PCM, well if you had a soundtrack of let say 21.5Mbps average variable bit rate how would you cram that into a Dolby TrueHD codec with an average bit rate maximum of 18Mbps?

The mesning of data compression is to take something big and make it littler. Like a zip file may contain far fewer bits than the orginal but when you unzip it you get the exact same thing you zipped. Lossless audio by definition squeezes out bits that it can easily rrconstitute so when you unpack it you getvexactly what you started with.
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post #74 of 81
2/4/13 at 4:20pm
Quote:
Originally Posted by PlayNice View Post


I find it funny how you are trying to state I do not know in a way to put down my intelligence. Yes I don't know that's why I started this thread, to learn and I enjoy learning so forgive me if I do not take your word as gospel and I do a little research of my own.

So thank you for pointing out LPCM is. To compressed but the other options are so if that is the fact then DTS would be the winner in compression, variable bit rates and all cause out I'd Dolby and DTS It looks to me DTS has the higher potential bit rate. Would I be wrong in saying that?

I say this cause you say if the source material is the same they will produce the same PCM, well if you had a soundtrack of let say 21.5Mbps average variable bit rate how would you cram that into a Dolby TrueHD codec with an average bit rate maximum of 18Mbps?

I can't really understand your second paragraph but both DTS HD MA and TrueHD have different bitrates due to different encoding algorithms. Just like how the lossy formats, DD/AC3 and DTS core, have different bitrates. A lot of people used to think DTS was better due to its 1.5mbps bitrate vs Dolby's 640kbps but in the end that was due to differences in encoding. (Roger D, formally of Dolby explained the differences in bitrates, search around on avs and you'll find it).
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post #75 of 81
2/4/13 at 4:40pm
Quote:
Originally Posted by PlayNice View Post

So thank you for pointing out LPCM is not compressed but the other options are so if that is the fact then DTS would be the winner in compression, variable bit rates and all cause out I'd Dolby and DTS It looks to me DTS has the higher potential bit rate. Would I be wrong in saying that?
The figure our merit for a lossless audio codec is how *low* its average bit rate is. The lower the better meaning the codec is more efficient. Think of it as 0 to 60 times for a car. The destination (60 mph) is fixed. Whoever gets there the fastest wins. The same with lossless audio. Both are producing the same bits and hence fidelity. Therefore the one with lows "cost" (bits to transmit or store) wins. Alas, the difference between the best and worst lossless codecs is rather small so the differentiation is not that big. Here is an article I wrote on this topic back a couple of years that explains all of this: lossless audio compression: http://www.madronadigital.com/Library/LosslessAudio.html

The above is in relation to the average bit rate. The peak rate of the lossless audio codecs is usually the same as as uncompressed since that is the worst case scenario. Given that, you can't really go by the peak rate as having value in differentiating codecs.
Quote:
I say this cause you say if the source material is the same they will produce the same PCM, well if you had a soundtrack of let say 21.5Mbps average variable bit rate how would you cram that into a Dolby TrueHD codec with an average bit rate maximum of 18Mbps?
That would be pretty poor compression ratio but from the fidelity point of view immaterial.
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post #76 of 81
2/4/13 at 4:42pm
Quote:
Originally Posted by pokekevin View Post

I can't really understand your second paragraph but both DTS HD MA and TrueHD have different bitrates due to different encoding algorithms. Just like how the lossy formats, DD/AC3 and DTS core, have different bitrates. A lot of people used to think DTS was better due to its 1.5mbps bitrate vs Dolby's 640kbps but in the end that was due to differences in encoding. (Roger D, formally of Dolby explained the differences in bitrates, search around on avs and you'll find it).
Lossy codecs are very different animals than lossless. I would not draw analogies between them as it is liable to create more confusion smile.gif.
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post #77 of 81
2/4/13 at 5:43pm
I don't pretend to understand how the lossless codecs actually work. But it would seem to me you could, for example, take one bit and use it to be a positive or negative sign, then cut the data rate in half (plus the one positive/negative bit). And when reconstituted the result would be bit for bit identical to the original.

Which reminds me, didn't somebody already demonstrate that both of the popular lossless codecs give bit for bit identical results to the original file? Or am I misremembering? In the end, I don't have to understand HOW they did it.
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post #78 of 81
2/4/13 at 6:18pm
poking around a little I found this description/explanation for those who like me want to understand at least at a simplified level. http://www.highdefdigest.com/news/show/1233
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post #79 of 81
2/4/13 at 6:25pm
Quote:
Originally Posted by JHAz View Post

poking around a little I found this description/explanation for those who like me want to understand at least at a simplified level. http://www.highdefdigest.com/news/show/1233
Unfortunately while Josh is a great writer, that explanation is not correct. I suggest reading my article where I keep the technical accuracy high while boiling down the complexity.
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post #80 of 81
2/5/13 at 12:24am
Quote:
Originally Posted by PlayNice View Post

It looks to me DTS has the higher potential bit rate.
You really believe that having a higher bitrate and taking up more storage space on the disc indicates a better compression codec? Do you understand the purpose of compression and why studios use it?
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post #81 of 81
2/9/13 at 1:00am
Quote:
Originally Posted by PlayNice View Post

I say this cause you say if the source material is the same they will produce the same PCM, well if you had a soundtrack of let say 21.5Mbps average variable bit rate how would you cram that into a Dolby TrueHD codec with an average bit rate maximum of 18Mbps?

PCM 21.5Mbps VBR does not occur in real because:
1. PCM is CBR.
2. PCM 7.1 24/96 is 18.43Mbps (8*24000*96)
3. PCM 5.1 24/192 is 27.64Mbps (6*24000*192)

Take two real examples both with all three PCM, dts-HD MA and Dolby TH tracks and you see typically dts and Dolby achieve nearly 50% compression or more:

Red Cliff BD (HK):
http://www.avsforum.com/t/1155731/new-unofficial-blu-ray-audio-and-video-specifications-thread/30#post_16697021

7.1 16/48:
PCM 6144kbps
dts-HD MA 2587kbps
Dolby TH 1996kbps

Divertimento audio BD (no BD info but player info display):
PCM 5.1 24/192 CBR: 27.64Mbps
dts-HD MA 13-15Mbps VBR
Dolby TH: 12-14Mbps VBR

You're very unlikely to see dts-HD MA or Dolby TH at higher bit-rates than this for BD. For movie BDs at 48kHz sample rate the typical bitrates for dts and Dolby are much lower. Plenty of examples in the Audio and Video Spec thread in the BD Software forum. The info has been there for a long time if only you look for it.
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