Axiom Home Page Forums General Discussion Home Theater Finally heard uncompressed 5.1 PCM

So I borrowed my parents blue-ray player and bought a copy of POC 3. Man o man!!!

The imaging with the QS8's was stellar! I think i'm going to go for the Panny DMP-BD10ak (DD True HD and DTS HD onboard decoders).

I really do not need to be hearing this...

Then you probably shouldn't read this:

The creaking of the wooden ships was very realistic. This wasn't even DD True HD, just uncompressed 5.1 PCM. The sound stage was amazing. All levels were pretty much spot on and everything was very smooth, no abrasive highs or muddy lows.

Oh...and the picture was AMAZING!! Some film grain was left in, making it very film like. There was one point in the beginning, (where some of the pirates were under the floor boards waiting for their cue to shove swords up through the floor) where the detail of the floor boards was stunning!

If you're like me where you have a receiver that does not decode DD True HD and the such, do not worry. Just get a player that decodes the audio internally and passes it as PCM over HDMI. I was sick with the thought that I bought this receiver earlier this year and it was already obsolete...but relieved when I discovered I could use PCM over HDMI.

I already have the HD video setup (HD DVD), but am not setup for HD audio...Not yet anyway...

Hurry up already Robb. How are we supposed to come over for a sub comparison with out HD? Sheesh.

So are you saying that 5.1 PCM is the same quality as DD True HD? The only difference is that you can only get 5.1 instead of 7.1?

Wouldn't uncompressed and losslessly compressed have to be pretty much identical? I mean, there are still ways to compromise that in certain hardware configurations, but shouldn't they tend to be exactly the same, quality-wise?

I am not even going to pretend to be able to answer that. I'm just saying that the Uncompressed 5.1 PCM sounds amazing and can't wait to hear DD True HD. But as the other posted stated, I believe they are the same, it's just that DD True HD supports up to 7.1 discrete.

I actually prefer Uncompressed 5.1 PCM to DD True HD, it seems more crisp Imo, that may be because it seems to play at a higher volume level than DD True HD when I switch back and forth during a movie, possibly at the same levels they would sound close to the same.

Michael,

DD-T-HD has dynamic compression encoded. Unless you can defeat that with your X2, the unpacked version your Denon is receiving may have DC enabled. I’m pretty sure that’s why it is lower than PCM. If it is sent as bitsream, the option is there to disable it, or select the amount of compression. But even with it disabled, there is a 4 db offset that I have not been able to figure out why is there. I had to set up the 3808 to bump up the input level for DD-T-HD. Other than that though, I can’t tell much of a difference in sound quality between it and MPCM. DTS-HD:M on the other hand….holy crap… it’s much mo’ better IMHO.

Mike,
Thanks for the explanation, I guess I'll have to wait for future upgrades to hear DTS-HD

Over the weekend I exchange my Poineer 1017 for a Yamaha 6190 which is the same as the Yammy 1800. Its full 1.3 HDMI.
I did the test with Spiderman BD on a PS3 and flip back and forth from bitstream DD 5.1 vs DD True HD vs 5.1 Uncompressed PCM.
Bitstream DD 5.1 was about 3db higher than the other 2 sources.
Quality is as it was in DD mode. What we have all been used to this past couple of years.
Switching to DD True HD the sound was 3db lower so I raised the volume and use my SPL meter and made sure I was listening the same DB. There was definitely lots of more nuance detail on each sound activity. I know this is subjective but it had a plethora of information which I was not aware about with the same track in DD 5.1.
I switch also to uncompressed 5.1 PCM and it was only a tad bit louder about .5 a db if at all. But sound quality at least to my ears were pretty much the same. I couldnt tell the difference much but I do always leave it at uncompressed 5.1 PCM.
Yammy also has some cool features like presence channel which add to the ambiance in the front so I have pretty much my main 2 speakers (+phantom center from main speaker) and 2 more presence speakers and the front sound stage is seamless and huge. The detail in the 4 speakers I have in front for HT is almost similar to what I get in critical 2 channel listening.
Still waiing in the new year for prices to drop for 1080p projectors or just cheap it out with a Benq W500.

Not just pretty much identical but in theory they should be bit-for-bit identical with absolutely no measurable difference all the way down to the last zero or one. But to know for certain we'd have to know that the compression process didn't do anything other than simply compress the audio, that the decompression similarly didn't apply any adjustments, and that the playback system treated both uncompressed and compressed audio in a similar manner. I'm not 100% confident that any of those three conditions are actually met in the real world.

Some information based on searches:

Dolby TrueHD is Dolby’s next-generation lossless technology developed for high-definition disc-based media. Dolby TrueHD delivers tantalizing sound that is bit-for-bit identical to the studio master, unlocking the true high-definition entertainment experience on next-generation discs
Features
-100 percent lossless coding technology.
-Up to 18 Mbps bit rate.
-Supports up to eight full-range channels of 24-bit/96 kHz audio

The new audio CODECs are lossless which simply means without loss, or identical to the original. The three lossless CODECs supported by both formats are LPCM(not really a codec), Dolby TrueHD and DTS HD MA. At this point the question should be, if they are lossless than what is the difference? The difference for the most part is the number of bits. Both Dolby TrueHD and DTS HD use far less bits than LPCM, this leaves more space on the disc for other features.

So how many bits are we talking about here. As an example a 2 hour movie with a 16/24, 5.1 sound track requires 4.14 GB with LPCM vs 1.26 GB for either TrueHD or DTS HD.

LPCM is not being used at higher than 48kHz sampling rate because of the datarate/storage that would require.

Dolby TrueHD definitely supports higher sampling rates than 48k

Uncompressed Linear PCM just like CD Audio. DTS-HD MA and TrueHD are lossless compression schemes aka codecs. DTS-HD (without the "MA") is a very high bitrate, yet LOSSY codec. DTS-HD Master Audio (or "MA" as most of us call it) is lossless.

So I ask this question would you rather listen to DTS-HD MA 24bit/48kHz since the disk has enough space for it or a "downres" the 24-bit, 48kHz LPCM master track to 16-bit, 48kHz LPCM?
I dont know the answer and I dont know if my ears can even tell.

LPCM offers nothing over TrueHD except it takes about about 2-3x the space. Either your player or receiver needs to support TrueHD and DTS-MA. But if the HD movie is mastered theoretically up to 192/24 (I don't think anything is done this high) you can fit a DD TrueHD and DTS-MA into the disks. Theres not enough room to have LPCM 192/24 in todays disks. We might need to wait for the quad sided Blue Ray disk on the PS5

Please correct any assumptions above.

Sat, the bottom line is that as far as formats go, and as recent tests have confirmed, the 16 bit 44.1KHz sampling rate standard CD meets or exceeds any requirements for frequency response of human ears and dynamic range possible for the source material involved. Of course the CD format is uncompressed per se and lossless compression should be equally good, as far as is known. Variations in the original recording process and later processing steps can make differences audible with any format, of course.

What tests are those John? I've read differently.

Mike, I've made the point about the complete sufficiency of the 16/44.1 CD format as far as actual audibility goes quite a few times here in the past few years. First, there was what appeared to me to be fairly obvious in that a 22.05KHz frequency limit exceeded human needs and a 98dB(6.02n + 1.76dB)maximum dynamic range exceeded the most dynamic recordings, which at most have about a 70dB range. Then, I also cited the explanation given on the S&V board by "Soundhound", a very experienced movie music engineering editor, who detailed how while using higher bit depth and sampling rates was fine to give room during the recording process, reducing this to 16/44.1 in the actual end product made no audible difference in his tests.

The recent tests confirming this that I referred to were published in a paper in the September AES Journal. The Journal isn't available online,but here's a brief description and discussion of the tests by the editor of the Audio Critic(an engineer). In brief, when DVD-A or SACD material was run through a 16/44/1 A/D/A to limit it to 16/44.1 no difference was detected in the blind testing. Any superior production values that resulted in better sound on the DVD-As or SACDs were unrelated to higher sampling and/or bit rates in the actual end product that was listened to.

Sorry John.... I mean no disrespect or to doubt you, but I am not buying that. The audio I've heard from 24 bit / 96 kHz is startling. Unless you have personally sat in on these “tests”, then I’d suggest you do so before making blanket statements. You just might be in for a hell of a surprise.

The trouble I see with saying, "you have to personally sit in on any test I doubt" is that then you can't believe anything anyone tells you. At some point you have to believe an authority of some kind.

I think there's still room to have doubts, and I see nothing wrong with wanting further verification. I'm willing to believe that perhaps CD audio is as far as we need to go with 2-channel, but for whatever reason, I find a lot more demo material in my SACD collection than in my whole CD collection. I'm willing to accept that this could merely be the extra channels at work, or a coincidental superior sound engineering for those discs, but it doesn't change the fact that from an audio quality perspective, I'm getting more out of a format that isn't CD. So, while I'm willing to go along with the idea that CDs CAN provide for the full range of human audibility, I'm still not 100% certain that there's not more to it.

Well, I'm not necessarily objecting in this situation. It's just I hate the specious argument of "Well, you didn't hear it personally, so you can't believe anything anyone says--but only if you disagree with my position."

Also, let me make it clear that I really enjoy my SACDs--for whatever reason; better mastering, 5.1 surround, etc.

I see your point. My response wasn't necessarily just to you, but to the thread in general. However, the thread was really about movie audio formats, and while I feel pretty safe saying that the new lossless formats beat the pants off their old lossy predecessors, I'm really not sure of how much difference can be heard between uncompressed, Dolby TrueHD, and DTS: HD Master Audio.

the real benefit of higher sampling rates is enjoyed by audio editors. A higher sampling rate affords for more accurate sample edits, say when trying to dial in on the perfect part of a drum beat, you can edit in more detail on the amplitude of the audio wave.

And I have a problem with people who will believe nothing but test results that are done by others, but only if they are in alignment with their personal beliefs or agendas and then stating them as absolutes.

If I, or anyone were to believe these “tests” that John speaks of, then why is there DVD-A, SACD, BR and HD-DVD in the first place? Oh wait, I suppose the “believers” will just coin that up to marketing…..never mind, no need to answer, I’ve heard it before from the trend and graph and one-watt is enough club members.

…….I’ll continue to enjoy high resolution audio even though the numbers confirm that I haven’t got a clue. I’ll also continue to enjoy 1080P/24 even though the numbers confirm I haven’t got a clue.

Mike, did you actually read that link that John sent? It seems pretty clear. There are a lot of other benefits to SACD/DVD-A (I'm not getting into the Blu-Ray HDDVD thing here) than just higher resolution/bitrate audio. Plus, they were talking about ideal conditions, if I read that right, which makes John somewhat incorrect; or at least makes his statement misleading.



Glad you enjoy it. I do too.

The objectivity of science in not an agenda, but an absolute requirement if your goal is anything resembling fact.

I agree with all of the above.
My dvd-a sound better than their cd counterparts, but whether this is due to a higher bitrate sampling or a different mastering to produce the dvd-a, is unquestionable (blind a/b tests at home make it unquestionable to me at least).
However, the limitation of cd also comes in the stereo form. Take that cd quality and spread it equally to every other channel in the audio system and you have one wicked surround experience.
No, Dolby Pro Logic for music does not even come close and sounds nothing like a dedicated dvd-a format across surround channels.
Anyone who has A/B'd that particular test (which i have, at home) would know the blue truck from the pink boat any given day of the year.

I like that analogy.

I just read this while eating lunch.
It seemed like an easy to read explanation of a few of the things being discussed.

http://hddvd.highdefdigest.com/news/show...less_Audio/1233

Thanks for the link. Good stuff.

That is a good artical. Now I know what the "offset" that pops up on my reciever's display when playing DDTruHD. I had thought it was dynamic compression, but I was wrong.