Dolby TrueHD vs. DTS-HD Master Audio - Page 4

Whew! After typing my post I started worrying that I had misunderstood something very basic, just because in general I take your posts as gospel re DD in particular.

aww thanks! But you probably meant to quote Roger haha

So in a dts-HD MA 192kHz 'stream' there is:
1. a dts core stream at 48kHz sample rate,
2. a lossless extension at 96kHz and
3. a second lossless extension at 192kHz (which with (1) and (2) makes up the whole lot, kind of 3-tier structure)?

I went back and reviewed the spec, and I must recant. It states that only one extension can be used at a time. Either 96 kHz or 192 kHz, but not both. My apologies, Kilian.

I'm afraid that leads to the conclusion that the Oppo is downsampling the audio. Frankly I cannot understand why -- all it has to do is send it to the HDMI, same as it does for 192 kHz PCM or TrueHD. Could it be that in order to support the internal processing for the analog outputs (bass management, perhaps delays), those resources are encroached by the HD MA decoder?

No need to apologise Roger and thanks for looking it up!

It's not confined to the Oppo. When I raised this before I was told by rdgrimes it was because Oppo uses the dts Essentials decoder. I don't know if it's the real reason or not.

I told Morten Lindberg at 2L about it and suggested using Dolby TrueHD instead and he said was he'd take it up with hardware manufacturers and that was about a year ago. At least I did try to push for Dolby for this cause as it obviously is the better choice.

Yep. "My aim ain't true"

Kilian,

I was able to learn something talking to a DTS insider. The spec I was referencing is rather old, and obsolete. It has been updated and published as an ETSI spec. The newer version indeed does allow for a dual band encode, so the 96 kHz result is indeed because the Oppo is discarding the extension band to 192 kHz sample rate, and nor due to downsampling. In the end, it's 6 of one, half-dozen of the other, but thought I should correct the record.

Thanks again Roger! If you do get another chance to probe, what's the reason for all players doing this?

It is up to the player maker, not DTS, and that probably means it is up to the chip maker. It reduces cost to reduce the processing load. In the early days when sample rates first exceeded 48 kHz, many AVRs and chips had to downsample to 48 Khz for all the post processing. That is actually still the case in some products.

Being that BD players are not primarily focused on audio processing, the DSPs are apparently less extravagant in that respect. And particularly since any enthusiast who is keen to get the 192 kHz experience can stream out the data, I suppose they figure it's not essential to make extra efforts for player decoding of 192 kHz for every codec. They of course ignore that niche of folks who prefer to use the analog outputs. I suppose if there were more than a handful of DTS titles at 192 kHz, a case could be made. But it's a pretty insignificant number.

I understand what you're saying. The implication is that there is more than one type of dts decoder or more than one implementation for dts-HD MA and the dts claim (on their website and in the whitepaper) about bit-for-bit identical to the master just isn't always true without qualification. They say dts-HD MA supports 5.1 192kHz but conveniently omit to tell you oh by the way not all our decoders can do that. It is this which I find a little misleading and annoying more than any real loss from downsampling.

The trouble with AVR decoding is, unlike player decoding there's no easy or sure way of knowing what happens to the sample rate internally whether other processing steps are applied or not, and if the DSP applies any digital band limiting filters to the output (some Onkyo/Integra models seem to do that).

I suspect the 2L titles were encoded before the dual band encoding update, therefore old and new players must be downsampling still.

The irony is that the PS3, a games console not focused on audio can fully decode dts-HD MA 192kHz from day one and the latest BD players, even 'audiophile', 'high-end' ones that focus on audio can't and surely processing power can't be a limitation any more with streaming, 3D, 4k etc.

Is all this concern over 2L and other niche content? Really the idea of 192 kHz is highly overrated for all the trouble it causes. Let alone the dearth of titles.

Even my lovely SSP-800 fully decodes DTS 192 kHz tracks then applies ASRC conversion to 96 kHz (same as Theta CBIII HD and others). This may sound like a sell out for 192 kHz, but it brings certain benefits in design, operation, and even sound quality (the DACs have better specs at 96 kHz than 192 kHz).
I'm not so sure. How can you tell?
Not exactly day one. The PS3 could not decode DTS-HD MA until 18 months after Blu-ray introduction. They had to completely rearrange the Cell chip resources.

No, again it's about the dts claim, a case of 'it doesn't do exactly what it says on the tin' (modified from a British expression).

Better address this to Morten L. and anyone making 192kHz audio. I'm only exposing the limitations, not the advocate. Don't shoot the messenger!

Divertimento came out in 2008, the ETSI DTS spec update was in 8.2011 (the one before was in 2002). Just putting two and two together. I can't be certain without asking Morten L which encoder he used but it's not a pressing issue.

BTW the update allows DTS-HD to do 384kHz (requiring a 3rd extension) and no longer needs the core.
OK, day one from the day it could decode.

I've made my point and let people know dts-HD MA decoding isn't always bit-for-bit identical to the source. Time to draw a close.

Not the first time. ALAC
Understood. BTW, the date the code is implemented is not necessarily related to the date the spec is published.
LoL, a sample rate war! The "coreless" option was there originally, but the Blu-ray folks did not want to use it, so that older DVD player chips could be pressed into service.