Old 04-26-2016, 08:19 AM   #1
audioadam
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Default How does Reaper "Fold Down" 5.1 to Stereo?

Reaper can have up to 64 audio channels per track. In the "routing help" dialog it says "Tracks can send audio from any channel on the sending track, to any channel on the receiving track."
Here is my question: If I have a 6 channel audio track (5.1 interleaved file) that is being routed to the default/checked "Master Send" (a 2 channel output) how does Reaper calculate the stereo fold down? Where are those settings?
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Old 04-26-2016, 08:41 AM   #2
serr
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There's no "autopilot" for that. Reaper only routes audio how you tell it to.

You could route a 5.1 track to a stereo bus by routing L,R to 1/2; Ls,Rs to 1/2; C to 1/2 (centered); and Lfe to 1/2 (centered). You could try reducing the pan width on the front L,R channels (keeping the rears 100% panned) and also adjust the level of front vs. rear to taste.

Most music surround mixes do NOT fold down to stereo very well of course (nor should they - 5.1 mixes made to work folded down to stereo are a compromise at best). Movie soundtrack surround mixes on the other hand are often made to fold down to stereo and still work.
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Old 04-26-2016, 10:33 AM   #3
DVDdoug
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Quote:
If I have a 6 channel audio track (5.1 interleaved file) that is being routed to the default/checked "Master Send" (a 2 channel output) how does Reaper calculate the stereo fold down? Where are those settings?
If that's happening automatically, it's probably being done by your soundcard driver. Or, you're just hearing 2 of the 6 channels.

In a Dolby Digital track there is metadata in the file that sets the levels when using a proper Dolby decoder. I'm not sure, but I believe default is -3dB center mixed-into front-left and front-right, and left-rear mixed into left-front and right-rear mixed into right-front at -3dB respectively. The 5 full-range channels contain the normal bass and the "point one" LFE channel is not included in the downmix. (The overall level may have to be reduced to prevent clipping.)

I don't know of any way to read the metadata from a Dolby track and if you have another 5.1 format there may be no such metadata.
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Old 04-26-2016, 10:51 AM   #4
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Quote:
Originally Posted by serr View Post
Movie soundtrack surround mixes on the other hand are often made to fold down to stereo and still work.
Which probably is the reason surround sound setups for movies are a surprisingly unattractive thing to invest into. I've noticed in movie and TV show soundtracks that the back channels are pretty much silent (or very quiet) most of the time, so there isn't much added value in having the back channels IMHO.
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Old 04-26-2016, 11:13 AM   #5
serr
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Quote:
Originally Posted by Xenakios View Post
Which probably is the reason surround sound setups for movies are a surprisingly unattractive thing to invest into. I've noticed in movie and TV show soundtracks that the back channels are pretty much silent (or very quiet) most of the time, so there isn't much added value in having the back channels IMHO.
Yep. Surround sound is for music.
I almost always skip the surround program for movies.

PS. If the original intention was to actually listen to the surround sound at the output if possible, set the master to 6 track channels and assign the outputs to your interface as needed.

Last edited by serr; 04-26-2016 at 11:55 AM.
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Old 04-26-2016, 02:03 PM   #6
analogexplosions
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There is a JS 8x2 Mixer plugin that does the trick for me.

Ch1 goes Left
Ch2 goes Right
Ch3 goes Center (-3dB,panned center for L-R)
Ch4 goes Center (I adjust level to taste, this is the sub)
Ch5 goes Left (-3dB)
Ch6 goes Right (-3dB)
Ch7 unused
Ch8 unused
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Old 05-24-2019, 06:20 AM   #7
daeavelwyn
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Old post still good ! Thanks
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