Hi All,

I was going to post this in the Blu-Ray thread but thought I would put it in here to be seen by both HD/BLU people.

To put it simple, I dont fully understand the differences between the different audio options becoming available on many Blu's and HD's.

I am aware that PCM is uncompressed but a lossy format. DD+ is compressed and lossy, which DTS HD MA & Dolby TrueDD are lossless audio formats.

Since my system can handle all (not sure if it does it well ) I thought I would ask what are the particular strengths of each format, along with a bit of background info if anyone can be bothered.

Only reason I'm asking is I noticed on my Close Encounters of a Third Kind it had three audio options (DD True HD, DTS HD MA & PCM). Am also aware that HD sounds does not always make a goode track, it depends on the source of the material

Best Regards,

Mathew

PCM is not a lossy format. PCM is essentially what every codec needs to be converted to before going into the DACs before being converted to audio.

I think the only reason for PCM, True HD and DTS MA is to allow for systems that might not be able to handle certain codecs.

You may find some are 24bit 96kHz or 24bit/192kHz whilst the PCM might only be 16bit/48kHz

Just having a quick read. It appears the reason you are saying PCM is lossy is that it often has had it's sample resolution reduced. i.e. 24bit>16bit. So in that sense it's lossy, but the codec itself is not technically lossy.

If you consider that PCM downconversion lossy, then 24bit/192kHz is also lossy since it's merely a sampled representation of the original analogue sound and will never match the original sounds perfectly.

A useful reference on PCM and LPCM

http://en.wikipedia.org/wiki/Linear_pulse_code_modulation

Iam noticing quite a few bluray movies that are still providing option of DD/DTS 5.1 as well as the new codecs. Maybe the legacy non hdmi AVR's still have a little more life in them??

I have also noticed the option of english descriptive 5.1. What is this? Is it output via digital optical/coaxial as well?

wow.... you completely LOST ME. ... and probably 95% of the population - especially the ones that have no idea about DD and DTS - especially the larger community that has never bothered nor considered to change a soundtrack from whatever is default on a DVD to DTS.



I add to mfedley's original post - the whole HiDef soundtrack gooblygook is damned confusing. Like - what is the difference between DTS HD and DTS HD MA ??

Take for example the HDDVD of THE DEERHUNTER (local version). The specs for this soundtrack stated DTS HD ('looked' impressive !), yet the soundtrack is very much MONO.


and further to mathew's request - maybe someone can provide us with some detail of how 'different' the sound is from plain ol DD and DTS ???

Okay for simplicity PCM is lossless and is basically the full copy of the sound file and takes up bundles of room on a disc, even too much when we are talking Blu-Ray.

DTS-HD MA and DD True HD are basically Dolby and DTS versions of zip files of the PCM. These are lossless but compressed and can be uncompressed by a player or AVR that can handle them.

Other HD codecs are lossy, but in some cases efficiently so and so the perceivable difference to the human ear is only minor if it is done right. Other cases of course a significant difference can be heard.

The reason Close Encounters has many is probably that they wanted a lossless Codec but after using it realised some people would never be able to hear it on the older players and with older AVR's so put PCM on there as well. That is my guess anyway.

http://media.bestofmicro.com/M/S/104500/or...e_full_size.png

The number of channels has little to do with the bitrate used. What suprises me is that now the technology is there why don't they develop more Blu-Ray audio only discs and put out stereo lossless recordings of some of the really good music that has to date suffered from being on CD.

Every Blu-ray must include a legacy soundtrack option, since a lot of people don't have amps that can deal with the new codecs. You'll always be able to hear sound from a Blu-ray if your amp can do DD and DTS.

English descriptive is a secondary soundtrack that describes what's going on if you have impaired vision. It's usually DD.

DTS HD is an umbrella term that includes both DTS HD HR and DTS HD MA. HR uses higher-bitrate than normal DTS (which maxes out at 1536kbps) but is still lossy. MA is lossless.

There are quite a few movies in mono DTS HD MA -- all old ones of course. If the movie was originally recorded in mono it's virtually impossible to make a multichannel mix out of it. However, it may still benefit from the losslessness since a lossy encode might in some cases exacerbate the flaws in the original.

I would say that the lossless codecs sound quite different from standard 448khz DD but not very different from full rate 1536k DTS.

DTS HD MA & Dolby True DD are lossless audio formats.

It would seem that Dolby True DD was favoured by HD-DVD and DTS HD MA was more favoured by BD.

But this is not exclusively true.

Thankyou all. I wanted to ask again for clarification and got my answer. I guess asking which is best out of the lossless formats is asking how long a piece of string is??

All of the lossless formats should sound the same, provided they use the same bit-depth (and even if they use different bit-depths they may sound the same to most people on most equipment). TrueHD and DTS-HD MA are more likely to use 24 bit, PCM more likely to be 16 bit, just because of the volume of data involved, but not always.

If you ask me, DTS-HD MA is the more elegant solution because it contains a legacy DTS track for older systems plus the extension to get it to lossless. But it takes a lot more processing power than TrueHD so it's less convenient in that respect.

Correct and well put.

Another great answer.

PCM was adopted on blu-ray due to the fact the format hit the market prior to the BDA being able to strike a deal for decoders from dolby. HD DVD was up and running and in the rush to "catch up" they needed market presence. Not a single player in the first round of Blu-ray releases has the capacity to decode (or bitstream) either Dolby True HD or DTS HD MA (in fact it took nearly a year to get the DTS HD MA decoders).

So PCM was adopted as the Lossless standard as an interim measure. At first it was thought that BD's space advantage would mean the inclusion of uncompressed PCM tracks would not effect quality and allow competition with HD DVD, but as it turned out, BD50's were not as easy to produce (and considerably more expensive with low yields) and as such all early BD's were on 25GB discs. The amount of space taken up by the PCM track in the early days, coupled with only 25 GB discs compared to HD DVD's 30 GB discs is why so many early BD releases are consider of a lower quality than the early HD DVD releases. Fortunately for the BDA, the release of 50GB discs and the PS3 solved all these problems.

PCM was never intended to be anything more than a stopgap measure. Fox studios didn't want to use PCM (or Dolby) and has always released with DTS HD MA tracks. This was a problem for many early adopters. With no players capable of decoding this format they were stuck with vanilla DTS audio. Sony pictures have completely dropped PCM in favor of Dolby True HD now that all players come with this capability. Disney still release some discs with PCM.

Mfedley heres a pretty good explaination

http://winebase.com.au/audio/index3.htm

Thanks for the link,very informative
Cheers
Thornton

Agree, Hopefully this thread has helped out a couple of other people including myself with the myriad of different audio formats

Hi Tonyjg,I love sound, and in my opinion I have never heard a Dolby Digital soundtrack that sounds better to me than a DTS soundtrack.I always select DTS if I have a choice,and in the past many DVD's had a choice. Not many DVD's have both soundtracks these days. Of course you need a "decent" AVR to play these options ,so it is good to own a quality system.
Luckily Blu Ray gives you a lot more audio options,but is harder for us to understand it all.
My AVR does standard lossy DD and DTS and hopefully uncompressed PCM, which I am keen to try out and do a comparison.
Now all I need is to decide on a Blu Ray player that will send my AVR a 5.1 analogue PCM signal.
Some more research is required
Cheers.
Thornton.

Hi peterjcat.

I thought this too until Ironman. You can select DD TrueHD in English but the only DD track is in Italian. Local disc too. Weird. My Rotel RSP1066 doesn't like it much either - I could only get sound out of the centre speaker until I selected one a 'pro-logic' like setting on the amp.

Regards,

Allan