Hi Neil.
When it comes to Blu-Ray authoring, do you consider it a cardinal sin to not include any codec-based streams on a disc?
As mentioned on here before, James Guthrie (the mixing engineer) apparently hates DTS, so that would leave only Dolby (True HD) as the only other viable stream for this release.
I've also said this before about this disc, but I really wish you would have authored this disc as the authoring is very amateurish with images and fonts that simply don't fit the intended mood or design for the album.
It's not so much a cardinal sin as it is a way to almost guarantee you will get returns by not including codec based audio in 5.1 because in the Blu-ray specs we have some very odd choices & decisions.
Because of the necessity to consider backwards compatibility, the format allows the use of TOSlink (lightpipe) and CoAxial Digital audio output but the downside is that because Blu-ray allows up to 24/192 in surround which will in no way fit down these connections in S-MUX mode (which is how it is configured in players) not to mention the possibility of 24/96 in 7.1 which again doesn't fit, the Blu-ray forum decided to disallow all lossless surround down so-called "legacy" connections so if you are using lightpipe or coaxial,
you simply cannot play the lossless surround in LPCM.
Yes - I know LPCM surround is mandatory in all players - but it is only mandatory over HDMIor (if available on the player) analogue out
This brings us to Codec audio, such as Dolby True HD & DTS-HD Master Audio.
However these also have their complexities. We all know (or think we know) that both DTS-HD MA and Dolby True HD are mandatory codecs for Blu-ray, which means all players must support them. What a lot of people (present company excepted, as you lot here are usually well on top of the game) do not realize is that they are not fully mandatory. In reality
only the lossy core stream is mandatory in surround.
This means that when playing a disc and using legacy connections it is quite possible to have the DTS-HD or the Dolby True HD lights on but actually be listening to DTS Core audio or AC3.
We made a very similar mistake when first starting on this format, and defaulted a disc to play the 5.1 LPCM stream instead of the DTS-HD variant (which was happily present on the disc) but never again.
It's a similar problem with 24/192 stereo as well - we cannot be certain (as nobody will confirm this at either Sony or Scenarist LLC) but we think that Blu-ray also handles 24/192 stereo as multichannel because again when playing over a legacy connection it doesn't work in LPCM (clue #1) and because when adding 24/192 stereo to a playlist in the Sony tool you have to use front left/right of the multichannel import dialogue, so again when faced with 24/192 stereo we now add this in DTS-HD MAS as default with an LPCM option for those who think they can tell the difference.
Other problems also exist with DTS-HD MA - most notably channel expansion. This is probably what annoys James, as when playing a 5.1 DTS-HD MA stream on a system configured for 7.1 through a DTS-HD essentials decoder it will automatically expand to 7.1 by doubling up the rear channels to the side channels - workaround is to encode to 7.1 with silent audio in the side channels. There is still one more issue we face with DTS-HD over an essentials decoder - it cannot handle DTS 96/24, and might do one of 2 things if presented with a 24/96 core stream:
A - output nothing
B - resample on the fly & output at 48kHz.
Dolby True HD does not perform automatic channel expansion, but it too has obvious issues most notably the same as DTS-HD MA and give you core audio over legacy connections which in this case is AC3/Dolby Digital. Yuk. Another huge issue is that the encoding tools only exist on Mac OS, not PC - yet there are no commercial grade Mac Blu-ray authoring systems so in effect you have to buy a Mac to use as a bloody dongle.
So, in effect, what we now do is put 3 streams as
1 - LPCM stereo 24/96
2 - DTS-HD MA 5.1 with a 48k core stream, (default selection)
3 - LPCM Surround
Also with our discs the coloured buttons will switch audio streams - yellow = LPCM stereo, Red = DTS-HD MA & Green = LPCM Surround.
Blue will take you to the next playlist in the navigation column in the onscreen layout.
Since we moved to Scenarist other refinements have been added - you now have an onscreen text telling you the active stream and the coloured buttons take you to the relevant stream type of the main playlist from the main menu.....plus another little refinement that will make it's debut on the THRAK Live Blu-ray in the forthcoming Box Set.
Our main focus & priority when doing a Blu-ray is to make it work reliably on as many systems as possible (we will not go into the whole Profile issue, as even though Profile 1.1 and Profile 2 have added refinements and increased total bitrates you dare not use these as you will potentially lose compatibility with older Profile 1.0 players) and additionally get you into the music as quickly as possible.
Fun, isn't it!