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[BUG] 7.1 mix down to 5.1 when extra channels > 0

(1/1)

mattkhan:
given 7.1 content, I would expect the following to produce exactly the same output

channels = 5.1
Mixing= JRSS

irrespective of what is selected in extra channels

in reality, this is not the case

for testing, I created a wav file which contains a 1kHz sine wave at -39dBFS in every channel

if this is played to a 5.1 output format with no jrss and extra channels =0 then RL/RR are discarded as expected

L R C Sub = -39
SL = -39
SR = -39

5.1 output format with jrss and extra channels = 0 then we see

L R C Sub = -42
SL = -36
SR = -36

I think this matches https://yabb.jriver.com/interact/index.php?topic=103299.0 (though I'm not sure it's ideal, does it make sense to amplify the surrounds relative to the front by so much?)

5.1 output format with jrss and extra channels > 0

L R C Sub = -39
SL = -39
SR = -39

i.e no mixing is performed, the content is just discarded

Matt:
Can you tell me steps to reproduce using our test tone creator?  I could play and watch Analyzer if I know what to look for.  Thanks.

mattkhan:
I emailed you the wav file I was using though I had forgotten about test tones, you can just use that instead

Mode = Tones
channels = 7.1
sample rate = doesn't matter, pick any

play this and look at analyser with extra channels set to a non zero value with 5.1 output and compare to extra channels = 0

you should see the difference in behaviour I described in the 1st post

Matt:
I think I see the problem.  Channel mixing was disabling when there were more than eight outputs.  But since they aren't real outputs, this should be changed.

We'll try to address this sometime in the future.

Thanks for the help!

mattkhan:
Thanks for finding the bug

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