5.1 Monitoring on Windows (Stereo Output)

[Ryan Gallagher]

Hello, first post/question. version 2.16.85 on Windows 10 Been using DCPomatic as a projectionist for the occasional pre-roll and extra content for a couple years and it's great.

I had an audio issue crop up I don't quite know the cause of. Have some ProResHQ video files created in a Atomos Samurai Blade (SDI) with 5.1 audio to the first 6 channels on the recorder. Unfortunately i'm stuck monitoring in stereo at the desk.

Two things I noticed. It appears the mapping requires swapping Lfe and C to get the DCP 5.1 mapping to be correct. I'm tempted to blame my cheap hdmi to sdi converter for this map issue? I believe this is my corrected mapping, but the L/R Ls/Rs are harder to judge by ear.

FromSDI_Mapping.PNG

2nd thing, While toggling the content audio channels while trying to identify them (after realizing mapping issues existed). I noticed that I never get any surround audio from my left headphone. It all comes from the right. But if I move that content channel elsewhere, I can confirm there is content on that channel. It feels like it might be a mix-down or monitoring issue in either windows or dcp-o-matic?

I tried a 5.1 download of this dolby file ( https://www.youtube.com/watch?v=21bPE0BJdOA ) and those channels mapped normally, but I still had the surround mix down missing content on the left ear when listening in stereo.

Restating for clarity. Any content channel placed on the Rs produces no audible monitor in the mixdown. However, the Right headphone speaker is the one I hear the Ls content from. For example. Placing all content channels on Rs produces no monitored audio in stereo. Placing all content channels on the Ls produces ALL monitored audio, BUT IT COMES FROM THE RIGHT headphone channel. L&R are not swapped somewhere in my hardware path because if I do the same for the L dcp channel, I get it from the left, and visa versa for the R, as expected.

Any thoughts?

[Ryan Gallagher]

AH HA! (answered the part 2 myself) Sometimes you just have to say the question out loud.

I decided to author the DCP of that dolby test file and try it in DCP-o-matic Player 2.

Had the same issue initially in the player. Checked settings. In the player you can also manipulate the stereo mix-down settings. Somehow my Rs channel had become unselected, and the Ls mix was placed on the R output channel too. I hit "restore to defaults" and everything was back to normal!!

This is weird, cause I'm pretty sure i've never modified that mix-down panel within preferences. Would be worth checking if a fresh install/update changed those? I didn't even realize could get to that audio settings panel in DCP-o-matic too. I had only noticed it previously in the player.

Apparently the player and the editor share those preferences. Fixing it in one place fixed it for both.

Player_settings_default.PNG