Interesting reading, here in the Theta thread. Cheers to that, and thanks for the kind comments. It is both my pleasure and our fun to be playing in the emerging 3d audio sandbox together. I’ve been invited via PM to comment on Trinnov Remapping with Theta processing. The short answer is that it can be a welcome enhancement, particularly for movies, to use Theta’s 5.1 to 7.1 up-mixing. To have it all done in the digital domain, so much the better.
Originally Posted by edorr
I am nearly 100% the Trinnov can generate 7.1 signal from a 5.1 source using remapping, because this has been discussed extensively on other threads. You should check with Curt, try it out and see how it compares the processing modes on the CBIII HD.
Originally Posted by LJG
No, this is not the case, I am 1000 percent sure as I speak with Curt almost nightly and have discussed this with him in its entirety. The Trinnov can ONLY generate the incoming source signal period. It can use all of your speakers to output a 5.1 signal say 7.1 speakers but it will be re-mapping and generating a 5.1 signal. I can choose to replicate a 5.1 SMPTE, or 5.1 ITU speaker setup from a 5.1 source
You are both correct. The basis of Remapping is a combination of the original channels and their intended positions relative to the listener (such as SMPTE, ITU, etc). This provides an intended 3D acoustic field. Trinnov then uses the actual measurements of any number of speakers and their actual positions in the listening room. A Fourier Bessel Transform (mathematical transform) is created and executed that will best transform/Remap tracks to speakers. The key is that this acoustic transform will take whatever the signal is and replicate the original acoustical image, using fewer or more speakers. 5.1 ITU could be transformed to Quad (4 speakers) or 11.1. Both are acceptable and will work to differing degrees. In this regard, you are both correct.
This is where it gets interesting: when and how we apply Trinnov’s Remapping technology. Let’s look at two cases which may explain LJG’s choices as well as clarify a bit how Trinnov fits in.
Film and ITU Music have nearly identical speaker placement assumptions, but can perform very differently. Why?
Film historically has high spatial resolution in the front, low spatial resolution in the back. Same for ITU (surround musiic standard), but there is a very big difference. 5.1 Film is mixed with rear channels feeding typically several loudspeakers covering a broad angle. Anything in the back is, by definition, filling a big spatial area. That is what happens on the dubbing stage. Any front to side to back panning covers broad areas. In tuning a theater, pink noise into a surround channel results in 2-8 speakers covering an area from 30+ degrees. Dubbing stage mixers, by definition, have little rear spatial resolution in a 5.1 mix. Now consider 5.1 ITU music: the recommended mixing layout is 5 loudspeakers in specific positions. Pink noise to any one channel, including rears, results in a point source. This is a very different outcome for the mixer, because precise images can be formed with reasonable results anywhere in the room (assuming a head forward attitude). Of course, these are generalizations, but serve well to illustrate our interaction with the source material.
In the case of the 5.1 film mix, Trinnov will build a stable, acoustical reproduction of the original mix over any number of speakers, including 7.1. What Trinnov won’t do is create spatial information that isn’t there. No surprise that a separate, external up-mix algorithm can add spatial life to the mix. This “sweetening” can also be done to some extent using existing tools in the Trinnov toolbox, including modifying level and delay to artificially add more depth and envelopment. But, for Remapping, that’s not the intended goal. With originating 7.1 film content, Remapping becomes much more interesting because there is more spatial resolution.
For 5.1 ITU music mixes, given the mixer’s much higher spatial resolution for mixing, there is typically a stunning amount of rear spatial information to be had in many of the mixes many of us have had the pleasure of listening to. In this case, Remapping will definitely take advantage of the extra spatial resolution, and it’s unlikely processing that audio further through 7.1 up-mixing is going to improve on that unless it’s an encoded mix intended for up-mixing on playback.
One must additionally take into account the room layout and listening position to fully appreciate the best approach. Some of us sit in the room, viewing on the long axis, while others choose to view across the short axis to take advantage of the bigger viewing wall, sometimes with a position near the back wall. These contrasting setups result in differing pros/cons for both audio and image. As one would expect, being near the back wall is typically more difficult to produce an effective 3D surround image then does being further into the room. In this context, LJG’s ongoing experience speaks well to combining the Theta’s processing with Trinnov Remapping.
Hope this helps clarify some aspects Trinnov’s Remapping technology and, in some cases, the combined benefit of additional processing.
Cheers to sonic purity...