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[Matt]

Hi all. We have a client playing 7.1.4 with a 16 channel output.

Today we map 16 channels with Channel_9, Channel_10, etc. after the first 7.1. This makes the .4 channels discarded since they're not in the 16 channel container.

We're considering switching so it starts with the same 7.1.4 and then Channel_13.

This would make anyone with DSP configured for channel 10, 11, 12, and 13 need to reconfigure it.

It seems like there's wide acceptance on the meaning 12 channel output so it seems reasonable to make this change.

Feedback welcome. Thanks.

[The Computer Audiophile]

Hi Matt, 9.1.6 is the standard 16 channel layout for Dolby Atmos (L, R, C, LFE, Ls, Rs, Lrs, Rrs, Lw, Rw, Ltf, Rtf, Ltm, Rtm, Ltr, Rtr). Not sure if this is helpful, but want to add it to the conversation.

[Matt]

Thanks Chris. I think we'll at least switch 16 channel to the standard then.

Also, we have the rears before the surrounds for 7.1.4 because that's what 7.1 does. Do you agree with that?

Thanks.

[mattkhan]

I've said it before but this sort of change is dangerous and I think MC should provide a transparent migration mechanism for the end user, i.e. if the config is stamped with the version then it's on MC to translate channel indexes at runtime to whatever the current version of the app uses

I think it's particular dangerous in this case because of a number of other points

1) the existence of an autoupdate feature
2) the existence of a major breaking change in a point release (hence auto updatable)
3) the way auto update can trigger by "surprise" (e.g. MC crashes and it jumps into auto update)
4) the complete absence of any warning to the user that this has just happened
5) historically high channel counts have been used in MC for active systems
6) silently remapping channels in an active system has the potential to be a system destroying event (either for a driver or your ears, oops we just sent your subwoofer feed to your tweeter and melted it)

[mattkhan]

having got off my high horse practically speaking I don't know why a particular format of source file interferes with channel mapping for an active system (which by definition must be playing lower channel count content)?

I have also said this before that your mapping from named channel to internal channel index should be treated as an append only list, i.e. you want to add a new named channel then it gets the next available index & even if you retire some channel name, you never reuse those indexes

your playback engine then needs to pick whatever channel indexes are relevant for a given content setup and use them

imv this is how you add new channel names without breaking everything

[The Computer Audiophile]

Thanks Chris. I think we'll at least switch 16 channel to the standard then.

Also, we have the rears before the surrounds for 7.1.4 because that's what 7.1 does. Do you agree with that?

Thanks.

7.1.4 Atmos has side surrounds before rear surrounds (L, R, C, LFE, Ls, Rs, Lrs, Rrs, Ltf, Rtf, Ltr, Rtr).

Given that Atmos is by far the biggest multichannel music format now, especially for music with over 8 channels, I think it makes sense to support the Atmos channel config.

That’s just me though.

[The Computer Audiophile]

I also think, if it’s possible, a great option would be to support both the traditional 16 channel selection in MC and a 9.1.6 selection. Traditional keeps everything the same. 9.1.6 routes to Dolby config.

[mattkhan]

I also think, if it’s possible, a great option would be to support both the traditional 16 channel selection in MC and a 9.1.6 selection. Traditional keeps everything the same. 9.1.6 routes to Dolby config.

I think this is another illustration of my point

there are various different channel layouts defined by source content which fits into the same physical set of outputs, from a dsp and physical connectivity point of view the output side needs to be fixed and there's no way to couple that to one particular source layout. Decoupling these is the way to go otherwise it's always going to break at some point.

[EnglishTiger]

Just to add some complexity into the mix the Samsung Q990D Q-Symphony has an 11.1.4 Configuration. Thankfully it's got an onboard-dac that can convert everything I throw at it into 11.1.4 format including Dolby Atmos Tracks.

[Matt]

Thanks a lot for the help everyone.

I think we'll add a new 16 channel output like "9.1.6 Channels (16 channel Dolby Atmos configuration)".

Then with that picked playing 7.1.4 should route nicely.

It won't disrupt existing configurations.

Thanks again.