ha, a bitstream vs lpcm test

[GardenVariety]

I have a pretty decent system, and although I wish I could say there is a difference, there's not to my ear. I've tested and tested and I can hear no audible difference. The only thing I would say is it's cooler to have the "DTS MA" on your receiver, that's it.

[Mase]

Originally Posted by MrAngles

You can't bitstream PCM. Setting the PS3 to bitstream has no effect on how it transmits a PCM track whatsoever, it states this clearly in the instructions (at least on my 60 gig model it does). Notice that when you bitstream any non-PCM track you no longer get pop-up menu sounds during the movie, but if you switch to a PCM track you get the menu sounds back.

That said, I'm an advocate of in-player decoding, as I like to hear everything the studio puts on the disc, including simultaneous audio streams, which are not supported by bitstreaming. Unless TrueHD and DTS-HD MA are not actually bit-for-bit representations of the master, the only thing a external decoder could possibly do that an internal one does not, is add post-processing.

LPCM/PCM is not a bit for bit representation of the master, it is the closest we have to that(for consumer technology) but it is not identical..

Techinically DTS HDMA is just as close, it is just compressed or more effecient, which is good since it allows our Blu-Rays to be packed full of more extras, directors cuts, ect ect...

[Solstice X]

Originally Posted by Mase

LPCM/PCM is not a bit for bit representation of the master, it is the closest we have to that(for consumer technology) but it is not identical..

Techinically DTS HDMA is just as close, it is just compressed or more effecient, which is good since it allows our Blu-Rays to be packed full of more extras, directors cuts, ect ect...

Where are you getting your info from? Lossless is just that lossless. When the studio provides you with PCM, DD TrueHD, or DTS-HD MA; they are providing you with a copy of the master track. It is bit for bit the exact same thing.

Speak with some audio engineers and then get back to me.

[MrAngles]

Originally Posted by Mase

LPCM/PCM is not a bit for bit representation of the master, it is the closest we have to that(for consumer technology) but it is not identical..

Techinically DTS HDMA is just as close, it is just compressed or more effecient, which is good since it allows our Blu-Rays to be packed full of more extras, directors cuts, ect ect...

Unless you're talking about a film that has an analog master, I'm not sure what difference you're talking about. In any case, what I was specifically referring to was lossless audio codecs' claim of providing a bit for bit representation of the master PCM file, and why if that's true all decoders should also be decoding the tracks identically to each other, bit for bit.

[JAWoOKIE]

Originally Posted by GardenVariety

I have a pretty decent system, and although I wish I could say there is a difference, there's not to my ear. I've tested and tested and I can hear no audible difference. The only thing I would say is it's cooler to have the "DTS MA" on your receiver, that's it.

I would have agree. I finally swapped my PS3 for a BD-30 last week. I like to know that my receiver is doing the work, but there is not a "huge" difference that I could honestly say I have noticed.

[crazzeto]

Originally Posted by Solstice X

Where are you getting your info from? Lossless is just that lossless. When the studio provides you with PCM, DD TrueHD, or DTS-HD MA; they are providing you with a copy of the master track. It is bit for bit the exact same thing.

Speak with some audio engineers and then get back to me.

if the source is analoge the he's right, but for digitally mastered sources ur right

[Mase]

Originally Posted by crazzeto

if the source is analoge the he's right, but for digitally mastered sources ur right

Thank you that is what I am talking about, PCM by nature is a lossless compression method and not bit for bit of the ORIGINAL MASTER..

The original just soo happens to be analog, so it cant be bit for bit and has to be converted to digital (binary code) and what is referred to as Lossless compression aka PCM or Pulse-code modulation..

Taken From wikipedia

In conventional PCM, the analog signal may be processed (e.g. by amplitude compression) before being digitized. Once the signal is digitized, the PCM signal is usually subjected to further processing (e.g. digital data compression).

Only on a technicality am I correct (in some cases)but none the less I am correct check this pic out, the red signifies the digital code and the grey line is of an analog sine wave, you will notice it is not bit for bit as there is some loss of data, most likely data our human ears can not discern, but a loss of data all the same.. Than again not everything is mastered in analog and vice versa, so a blanket statement like PCM is bit for bit of a master is innaccurate in some if not most cases..



EDIT: Ok so I tried finding out what percentage of Films are digitally mastered in the audio department and I could not find any such info.. Most of the stuff I found was still stating analog is the preferred method but this is from a couple years ago, soo it doesnt really help.. I did read however that most TV shows are digitally mastered both for picture and sound. Soo it appears I am incorrect in my previous statement, as its most likely a 50/50 situation.. It was also brought up that a PCM track can be down rezzed which would make it less than equal to a master, but unless any of us get the full specs on the master than we are all playing the guessing game.. Still this is an interesting topic

[Da Man]

Those guys with the expensive recievers like to argue that PCM introduces jitter that they can notice.
And a note, a lossless/PCM track can be downressed Warner which wouldn't be copy of the master.

[SLARITY]

Originally Posted by Mase

Thank you that is what I am talking about, PCM by nature is a lossless compression method and not bit for bit of the ORIGINAL MASTER..

It is bit for bit if it was originally recorded digitally.

Most of the time you are correct because most movies would be made with an analog signal then converted to digital and thats what your talking about.

[MrAngles]

Originally Posted by Mase

Thank you that is what I am talking about, PCM by nature is a lossless compression method and not bit for bit of the ORIGINAL MASTER..

The original just soo happens to be analog, so it cant be bit for bit and has to be converted to digital (binary code) and what is referred to as Lossless compression aka PCM or Pulse-code modulation..

Taken From wikipedia


Only on a technicality am I correct (in some cases)but none the less I am correct check this pic out, the red signifies the digital code and the grey line is of an analog sine wave, you will notice it is not bit for bit as there is some loss of data, most likely data our human ears can not discern, but a loss of data all the same.. Than again not everything is mastered in analog and vice versa, so a blanket statement like PCM is bit for bit of a master is innaccurate in some if not most cases..



EDIT: Ok so I tried finding out what percentage of Films are digitally mastered in the audio department and I could not find any such info.. Most of the stuff I found was still stating analog is the preferred method but this is from a couple years ago, soo it doesnt really help.. I did read however that most TV shows are digitally mastered both for picture and sound. Soo it appears I am incorrect in my previous statement, as its most likely a 50/50 situation.. It was also brought up that a PCM track can be down rezzed which would make it less than equal to a master, but unless any of us get the full specs on the master than we are all playing the guessing game.. Still this is an interesting topic

All films must be digitally mastered to be put out on DVD, Blu-ray and digital projection systems, because they are digital mediums. Lossless audio codecs supposedly provide a bit for bit reproduction of that digital master, but compress the data so it takes less space on the disc. As far as the digital master's representation of an analog source, "bit for bit' is not applicable, as analog sources have no "bits." PCM is not a compression method at all, just a method of storing audio digitally, and when sampled at a rate as fast or faster than the human ear can detect, should be completely transparent to any analog source. If the analog source is processed in any way prior to digitization, of course that processing will also be in effect in the digital version.

[Mase]

Originally Posted by MrAngles

All films must be digitally mastered to be put out on DVD, Blu-ray and digital projection systems, because they are digital mediums. Lossless audio codecs supposedly provide a bit for bit reproduction of that digital master, but compress the data so it takes less space on the disc. As far as the digital master's representation of an analog source, "bit for bit' is not applicable, as analog sources have no "bits." PCM is not a compression method at all, just a method of storing audio digitally, and when sampled at a rate as fast or faster than the human ear can detect, should be completely transparent to any analog source. If the analog source is processed in any way prior to digitization, of course that processing will also be in effect in the digital version.

I would read up on that if I were you, Pule-Code Modulation is considered a lossless compress method.. I have found no evidence that it is not, in fact there are many Lossless compression methods..

The fact of the matter is that someone stated PCM is exactly what the studio intended you to hear bit for bit, well that is and isnt true, since you cant represent a full analog sound wave with PCM or any other digital codec.. The fact that you even state in your own post that what is being lost from taking an analog signal and mastering it to a digital representation is something we humans can not discern spells it out for all of us..

And for the record how many digital projection system are out there? I will tell you not very many, and that fact was found out just recently as well with the release of Journey to the center of the earth requiring a digital projection system to show it in 3D.. In fact the studio had to change the title of the film because of this exact reason, this is what leads me to believe that motion pictures are still using analog sources for audio, which in turn means no matter how good PCM sounds it is not indentical to the original..

That does not mean that it doesnt sound fantastic and that we are actually losing out on anything, but for debates sake, well you get the picture.. Someone has to be on the opposing side of this debate

EDIT: also when I said mastered I meant original source material, I think we all know that to be on a disc it has to be digital.. Sorry for my misuse of words

[Solstice X]

Originally Posted by Mase

I would read up on that if I were you, Pule-Code Modulation is considered a lossless compress method.. I have found no evidence that it is not, in fact there are many Lossless compression methods..

The fact of the matter is that someone stated PCM is exactly what the studio intended you to hear bit for bit, well that is and isnt true, since you cant represent a full analog sound wave with PCM or any other digital codec.. The fact that you even state in your own post that what is being lost from taking an analog signal and mastering it to a digital representation is something we humans can not discern spells it out for all of us..

And for the record how many digital projection system are out there? I will tell you not very many, and that fact was found out just recently as well with the release of Journey to the center of the earth requiring a digital projection system to show it in 3D.. In fact the studio had to change the title of the film because of this exact reason, this is what leads me to believe that motion pictures are still using analog sources for audio, which in turn means no matter how good PCM sounds it is not indentical to the original..

That does not mean that it doesnt sound fantastic and that we are actually losing out on anything, but for debates sake, well you get the picture.. Someone has to be on the opposing side of this debate

EDIT: also when I said mastered I meant original source material, I think we all know that to be on a disc it has to be digital.. Sorry for my misuse of words

The standards today call for mastering audio in digital and for most commercial cinemas, playing the audio digitally. For Dolby Digital you will find that the information is pulled off optically from the extreme side of the film. For DTS, however, the audio is played with DTS CD's. The timing of course being taken off a signal on the film.

With digital masters, the rate at which the recording is taken is such that, that arguing between the quality of a high rate digital master and the quality of an analogue master would be a moot point.

The claim by DD and DTS is correct, that their HD codecs are a bit for bit representation of their "digital masters."

Also, film is mastered now in 4k or 2k digital jpeg2000. So the goal would be to get the audio from this in a lossless form. Audio, they can do it; Video, we've got a ways to go.

[Mase]

Originally Posted by Solstice X

The standards today call for mastering audio in digital and for most commercial cinemas, playing the audio digitally. For Dolby Digital you will find that the information is pulled off optically from the extreme side of the film. For DTS, however, the audio is played with DTS CD's. The timing of course being taken off a signal on the film.

With digital masters, the rate at which the recording is taken is such that, that arguing between the quality of a high rate digital master and the quality of an analogue master would be a moot point. The claim by DD and DTS is correct, that their HD codecs are a bit for bit representation of their "digital masters."


Also, film is mastered now in 4k or 2k digital jpeg2000. So the goal would be to get the audio from this in a lossless form. Audio, they can do it; Video, we've got a ways to go.

The end result for performance is a moot point I do agree, but what I was originally debating, is the fact that LPCM tracks on Blu-Rays are not indentical to what the studio has recorded, they cant be if its coming from an analog source.. As far as being bit for bit of the "digital master" they can be, but only if they are noT down rezzed, which they do from time to time.. There are too many variations from either the source material to how a Blu-Ray movie is authored to say for sure that PCM is indeed bit for bit...

Regardless of all the technical bs, it still sounds good

[Solstice X]

Originally Posted by Mase

The end result for performance is a moot point I do agree, but what I was originally debating, is the fact that LPCM tracks on Blu-Rays are not indentical to what the studio has recorded, they cant be if its coming from an analog source.. As far as being bit for bit of the "digital master" they can be, but only if they are now down rezzed, which they do from time to time.. There are too many variations from either the source material to how a Blu-Ray movie is authored to say for sure that PCM is indeed bit for bit...

Regardless of all the technical bs, it still sounds good

Fair enough, WB and Sony have been guilty of doing that on a few accounts on some earlier BD discs. However, going forward, the studio PCM's are what should be zipped in to the HD codecs. As far as catalog, they should match the remastered version if HD codecs are used.

[crazzeto]

This isn't true, all films must be transfered to a digital format but there's nothing that says they can't be mastered on analoge sources. Pirates was shot of film for instance. Or better, consider star wars, or the original indiana jones movies, both of these were fully mastered on analoge sources and the digital forms technically will never be truely repersetitive of the original masters.

That said, with a high enough sample rate it really doesn't matter. 24/48 still leaves some room for improvement, but that doesn't mean that it isn't excellent. Maybe one of these days we'll get 24/96 lossless.

Originally Posted by MrAngles

All films must be digitally mastered to be put out on DVD, Blu-ray and digital projection systems, because they are digital mediums. Lossless audio codecs supposedly provide a bit for bit reproduction of that digital master, but compress the data so it takes less space on the disc. As far as the digital master's representation of an analog source, "bit for bit' is not applicable, as analog sources have no "bits." PCM is not a compression method at all, just a method of storing audio digitally, and when sampled at a rate as fast or faster than the human ear can detect, should be completely transparent to any analog source. If the analog source is processed in any way prior to digitization, of course that processing will also be in effect in the digital version.