Dolby/DTS question about source audio vs surround modes

Wowarning

Novice Member
So, I have a Denon AVR E400 receiver, and I hooked up a new center channel speaker last night and wanted to play something to test it out. I put on a movie through Plex (on Tivo Bolt connected via HDMI) that the info tab shows having 6 channel source audio - however, my receiver will only allow Dolby PL II (Cinema, Music, Game) or DTS:Neo 6 (Cinema, Music) as available surround modes. I was under the impression that both of these surround modes take 2 channel source audio and, through algorithms, they "create" additional channels. I was hoping to listen to the audio in 5.1 as it was originally encoded, but can't find a way to do so (to the best of my knowledge.) Am I doing something wrong, or am I confused about what these technologies actually are and what they do?
 

dante01

Distinguished Member
What format was being output from the source to your AV receiver? The indicators on the front panel may be indicatoring the speakers connected and being utilised in association wit the upmixing mode you've engaged? You need to configure the source so that it bitstreams audio rather than having it set to an option that results in it downmixing multichannel audio into just 2 channel PCM.

If able to apply PLII or NEO:6 then the audio you are receiving is not 5.1 in nature and more than likely only 2 channel stereo. 5.1 Dolby Digital and DTS or other multichannel formats would negate such upmixing and the receiver would indicate the just the incoming format on its display as opposed to showing an upmixing mode it is able to apply.

Basically, your sources isn't outputting discrete multichannel audio to your AV receiver.
 

dante01

Distinguished Member
While playing a source, go into the GENERAL settings and select the INFORMATION option. Use the AUDIO option to ascertain the exact format (INPUT SIGNAL) coming into the receiver and the exact number of discrete channels (FORMAT) it consists of. Th AUDIO INFORMATION will also indicate any additional modes you may be applying to this audio in the form of the SOUND MODE entry.
 

Wowarning

Novice Member
The Tivo Bolt has only 2 audio output settings - Dolby Digital, and PCM. I'm currently set on Dolby Digital, so I would have thought it would output multi-channel audio. If I put a TV show on, I have the option of "Dolby Digital" on the receiver as a surround mode.
 

dante01

Distinguished Member
The Tivo Bolt has only 2 audio output settings - Dolby Digital, and PCM. I'm currently set on Dolby Digital, so I would have thought it would output multi-channel audio. If I put a TV show on, I have the option of "Dolby Digital" on the receiver as a surround mode.
Dolby Digital can include fewer channels than 5.1 and many TV shows broadcast via channels that encode their audio using Dolby Digital are only stereo in nature despite being encoded with Dolby Digital. Dolby Digital doesn't mean the audio consists of more than just 2 channels of audio. Upmixing would still be applicable to 2 channel Dolby Digital. It is only when the audio consists of 5.1 or more discrete channel of audio that the upmixing modes would be negated and bypassed.

Dolby Digital is a format and not a mode. You cannot switch it on and off. The upmixing is applied to it and not instead of it.
 

Wowarning

Novice Member
So I took a look at the info and here's what I found. When playing a TV show with Dolby Digital audio, the receiver says "sound - dolby digital, signal - dolby digital, input signal - 6 channels highlighted in blue, active speakers - 6 highlighted in blue" When I pop into Plex and play the movie (which states the sound is in 5.1 DTS and the info tab in Plex shows audio - 6 channels), the receiver shows "sound - dolby pl ii - cinema, signal - PCM, input signal - only FL and FR highlighted, active speakers - 6 highlighted.
 

Wowarning

Novice Member
Just tried on Plex on the PS4 and it's exactly the same situation. The PS4 is hooked up differently also - it goes directly into the one of the hdmi inputs on the TV and then the audio goes back to the receiver on the ARC via hdmi. I'll keep playing around, but I can't figure out why I can just listed to the 6 channels of audio that are there. Very odd.
 

dante01

Distinguished Member
Note that some TVs cannot passthrough multichannel audio via ARC if accessed via an external HDMI source connected to that TV. Also ensure that the TV is configured to bitstream audio as opposed to being set to a PCM option in association with its digital audio output setting. If set to PCM then it will downmix all audio and output it as 2 channel PCM.

I'd suggest you connect sources directly to your AV receiver via HDMI as opposed to passing audio through your TV. You'd gain access the HD formats such as DTS-HD Master Audio and Dolby TrueHD via a direct HDMI connection. THese formats cannot be conveyed via regular HDMI ARC.
 

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