GRV Posted March 10, 2019 Share Posted March 10, 2019 I have had an C4-LU862D (4K 8x8 Matrix) installed for about year. I have not been able to get a stereo output at the RCA stereo downmixed from a Dolby Atmos signal. The spec sheet clearly states: Audio formats: All common surround sound formats including Dolby Atmos, Dolby Digital, Dolby Digital EX, Dolby Digital Plus, Dolby Pro Logic II, Dolby Pro Logic IIx, Dolby Pro Logic IIz, Dolby TrueH Analog stereo derived from all audio formats listed above. Programmable audio delay up to approximately 255 ms. Outputs match and follow HDBaseT/HDMI outputs. Models supporting audio downmixing can simultaneously ouput supported surround formats and downmixed stereo audio over HDMI, HDBaseT, and analog audio outputs. The Dolby Atmos signal is derived from programs/movies/shows on Netflix, Prime, and Apple Movies via the latest generation 4K AppleTV (model A1842) connected to the C4-LU862D. When routed to an AV receiver it is clear that the Dolby Atmos signal is recognized (by the AVR) but not being downmixed to stereo. I should mention that the stereo signals from the C4-LU862D are processed through an older C4 16-channel audio matrix (C4-16S2-E-B). The dealer has been unable to resolve and a tech request has gone into Control4 with no response yet. Anyone else experiencing this issue and, if so, have you been able to resolve it? Thanks. Quote Link to comment Share on other sites More sharing options...
Cyknight Posted March 10, 2019 Share Posted March 10, 2019 It certainly should be doing it - it does it just fine on mine. The audio matrix won't make a difference. Question, if you force the source to stereo ARE you getting a signal? Because if not, it could 'simply' be that the audio output on the LU is set to 0% volume....or just very low Quote Link to comment Share on other sites More sharing options...
GRV Posted March 10, 2019 Author Share Posted March 10, 2019 When I turn off Dolby Atmos on the AppleTV, shows revert to a 5.1 signal (Netflix as an example) and I get a good stereo signal (downmixed). Quote Link to comment Share on other sites More sharing options...
GRV Posted March 10, 2019 Author Share Posted March 10, 2019 BTW, the matrix is on Firmware v2.25. The driver is version 318. Quote Link to comment Share on other sites More sharing options...
tcwalker5 Posted March 10, 2019 Share Posted March 10, 2019 I have the exact same problem. Quote Link to comment Share on other sites More sharing options...
GRV Posted April 7, 2019 Author Share Posted April 7, 2019 Cyknight -- do your Output to Audio Mappings look similar? I have no SPDIF Audio Inputs hooked up currently. Wondering if this setup is affecting Dolby Atmos from coming across. Audio Output 1 (Audio Matrix) <--> SPDIF Audio Input 2 Audio Output 2 (Audio Matrix) <--> SPDIF Audio Input 2 Audio Output 3 (Audio Matrix) <--> SPDIF Audio Input 2 Audio Output 4 (Audio Matrix) <--> SPDIF Audio Input 4 Audio Output 5 (Audio Matrix) <--> NOT SELECTED Audio Output 6 (Audio Matrix) <--> SPDIF Audio Input 6 Audio Output 7 (Audio Matrix) <--> NOT SELECTED Audio Output 8 (Audio Matrix) <--> Source 5 Quote Link to comment Share on other sites More sharing options...
GRV Posted April 24, 2019 Author Share Posted April 24, 2019 Regarding this issue, the latest from my dealer: "...Control4 [to my dealer] have explained the video switch is not physically capable of decoding Atmos from an Apple TV. The options are to either continue to use it without Atmos decoding, or we can offer an RMA for credit." Interesting that it is an AppleTV issue. I have not tried another non-AppleTV source yet. Quote Link to comment Share on other sites More sharing options...
Cyknight Posted April 24, 2019 Share Posted April 24, 2019 38 minutes ago, GRV said: Interesting that it is an AppleTV issue. I have not tried another non-AppleTV source yet. News to me. But I can tell you that I can decode Atmos from Two BluRay players and two Rokus no issue. I don't use AppleTV. Quote Link to comment Share on other sites More sharing options...
cardcotech Posted February 7, 2021 Share Posted February 7, 2021 This is because Apple TV’s “Atmos” is its own special flavor of Dolby Atmos called “MAT.” Can’t remember what it stands for exactly but it’s a PCM-ready version of Atmos that the C4 matrix can’t downmix. The only matrices I know of that can downmix Apple TV Atmos are the AVPro Edge models with updated MAT-downmixing cards. Quote Link to comment Share on other sites More sharing options...
GRV Posted February 7, 2021 Author Share Posted February 7, 2021 @cardcotech Thanks for the explanation -- it has been a mystery. Recently, I installed the Roku 4K ultra which offers content in Dolby Atmos and even that cannot be played in the stereo speaker rooms. Ultimately, I had to select the Dolby+ | DTS as the default audio for Roku. (?) Quote Link to comment Share on other sites More sharing options...
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