DTS-HD support with DTS unchecked in audio settings

[spmcewen]

I realize there are limitations with tvOS that makes passing through DTS difficult and passing through DTS-HD probably impossible. Here's my setup: Apple TV 4 connected to a Denon AVR-s700w. I'm playing back a blu-ray rip I made that contains just the video and the DTS-HD MA audio track.

MrMC has audio passthrough enabled and DTS/DD/EAC3 support all enabled. When I play the file the receiver lights up with "DTS".

If I disable DTS support in the MrMC audio settings and play the file I assume that MrMC is now decoding and sending PCM? The receiver lights up with "Multi-In". What exactly is MrMC doing here - how can I tell if it's decoding the DTS-HD MA audio track or just the DTS core? I realize that having MrMC decode and send lossless PCM should result in the same audio quality, I'm just not sure how I can tell which version (core vs HD) of the DTS MrMC is using.

Is there any reason I shouldn't just disable passthrough altogether and always allow MrMC to decode and send PCM to the Denon?

Thanks!

[davilla]

For DTS-HD and MrMC set to 7.1 AND atv4 set to highest. Then multi-channel PCM is passed. My denon W3200 will show all 7.1 channels and their mapping.


DTS core would be 5.1 channels not 7.1 channels of DTS-HD.


You could, some do that and are fine with the result. Some say passthrough 'sounds' better.

[spmcewen]

Thanks for the reply.

My room layout only allows for 5.1 (couch against back wall) so I have just the 2 surround speakers and MrMC set to 5.1 channels. I do have the atv4 set to use "best quality available" audio. Does this mean that only the DTS core and not DTS-HD will not be sent as PCM if I disable passthrough? I thought the discrete 7.1 formats were backwards compatible with 5.1 configurations.

I don't think this is a huge deal - I'm not even convinced my speakers and ears are good enough to tell the difference between lossless DTS-HD and lossy DTS. I'm just curious how it all works. I can't tell any difference when my receiver shows "DTS" versus "Multi-in". AFAIK the Audyssey room correction filters are applied regardless.

[davilla]

debuglog will show what is going on when you play something. It's a little hard to understand at first until you know what to look for.

[spmcewen]

Ah, thanks. I always wondered how to get to the debug logs. I'll check that out tonight.

[cosmoxl]

Thanks for the reply.

My room layout only allows for 5.1 (couch against back wall) so I have just the 2 surround speakers and MrMC set to 5.1 channels. I do have the atv4 set to use "best quality available" audio. Does this mean that only the DTS core and not DTS-HD will not be sent as PCM if I disable passthrough? I thought the discrete 7.1 formats were backwards compatible with 5.1 configurations.

I don't think this is a huge deal - I'm not even convinced my speakers and ears are good enough to tell the difference between lossless DTS-HD and lossy DTS. I'm just curious how it all works. I can't tell any difference when my receiver shows "DTS" versus "Multi-in". AFAIK the Audyssey room correction filters are applied regardless.

You can still tell MrMC to output 7.1 and your receiver will take that input and output 5.1. That way you can confirm that DTS-HD is being used by seeing a 7.1 input to the receiver.

Or, connect to the web server of MrMC (same as to get the debuglog), and, using the remote section of that web GUI, click codec. That will overlay important info.

[spmcewen]

Here are the logs I captured. I force quit and did a fresh MrMC start for each test. I played the same video file each time - a blu ray rip with only a DTS-HD MA audio track. I looked at the codec OSD each time and it's always like this: https://i.imgur.com/qpoOw8W.jpg -- Audio: DTS (DTS-HD MA). My receiver however always shows "DTS" or "Multi-In" when passthrough is disabled.

The logs:

With passthrough, 5.1 channels selected, and DTS enabled:
https://pastebin.com/raw/tNW4y1MM

With passthrough, 7.1 channels, and DTS enabled:
https://pastebin.com/raw/wuMZaSPs

With passthrough disabled, 7.1 channels:
https://pastebin.com/raw/Ubs5HfWd

[edit] I'm not a C developer but taking a look at AESinDARINIOS.mm I notice this in the 3.0.3 branch:

Code: Select all

  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_AC3);
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_EAC3);
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_DTS_512);
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_DTS_1024);
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_DTS_2048);
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_DTSHD_CORE);
  // ATV can not do below (yet :)
  // device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_DTSHD);
  // device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_TRUEHD);

This matches the stream types I see in the logs above, which I noticed only shows STREAM_TYPE_DTSHD_CORE

[davilla]

Maybe was not clear. Your receiver will never show DTS-HD. The requires passthrough at a sample rate of 192KHz, which is not supported on the AppleTV4. The best you can do is DTS-HD -> multi-channel PCM.

[cosmoxl]

And I meant that if you saw 7.1 *PCM* channels input in your receiver you'd know DTS-HD was being decoded rather than just the core. I didn't mean to make it sound like HD audio passthrough worked.

[spmcewen]

oh - I actually do understand that. I know my Denon will never show DTS-HD with this setup. My original question was how could do I really know DTS-HD MA versus the DTS Core is being decoded to the multichannel LPCM? I have 5.1 speakers and my source file is 5.1 DTS-HD MA - it's not 7.1.