Notes on Premiere Pro Multi-channel Audio

I had an opportunity to export audio for a video edited in Premiere Pro as 8-channel, and
there were so many trap-like steps that I almost lost my temper, so I'm summarizing them here.
MOV format onlyThese are the settings for exporting. Please note that MP4 is not supported.

❶ Material Preparation

Splitting Stereo to Mono

Basic voice material is mono (1ch), but sometimes the material provided is stereo (2ch). This is just a state where the same audio is lined up twice.
If you drop it into the sequence as is, it will consume two channels in the final export, so let's split them.
It's too late if you realize you want to split them after doing a lot of editing and cutting!

1. Right-click the imported material, select Modify > Audio Channels, and the Modify Clip window will open.

2. In the Audio Channels tab, change the Clip Channel Format to "Mono".

3. Change the Number of Audio Clips to "2".

After this, if you drop the material into the sequence, the audio that was panned left and right will be separated into different tracks, so delete one of them.
The fact that you can't split them after dropping them into the sequence is really...

Is it okay to leave BGM and SE as they are?

It's fine to leave them as stereo, but I will omit that here because the subsequent settings become complicated.
(I will add it later if there is demand.)

❷ Sequence Preparation

Multi-channel settings are a one-shot deal!

Do you think you can export in multi-channel just by increasing the audio tracks?Unfortunately, you caaaaaaaan't!!
(OMF export is fine with the sequence as is.)

1. Create a new sequence > Open the New Sequence window.

2. Tracks tab > Change Mix to "Multi-channel".

3. Change the number of channels to 8 (setting it to 10 as a reserve makes editing work easier).

4. Press the "+" button to increase the required number of tracks to 8ch (setting it to 10ch as a reserve makes editing work easier).

5. Track type... Adaptive.

6. Output assignment... Click the icon > The Track Output Channel Assignment window will open.

7. Audio 1... Check only "Channel 1-1" (far left, 1st row from the top) > Click OK to close.

8. Audio 2... Check only 'Channel 2-1' (leftmost column, 2nd row from top) > Click OK to close

9. Audio 3... Check only 'Channel 3-1' (leftmost column, 3rd row from top) > Click OK to close

10. ...From here on, check only the leftmost box for each row in order from the top and click OK to complete the sequence setup

Please note that items 2-5 above must be selected during sequence setup, as they cannot be changed later.
Items 7-10 can be fixed later, so it's okay if you make a mistake checking them.
It looks like a matrix, but the fact that you only ever need to check the leftmost column is a real trap...

❸ During sequence work

Can't monitor audio from channel 3 onwards...?

Now, I can finally start working... Wait?
I've laid out the footage, butI can't hear the audio from channel 3 onwards!?
I can't hear it in the mix?! I can't work like this!
It's okay.There is a way to hear it in the mix with a single button.

Window >Audio Track MixerOpen
*Note: This is not the Audio Clip Mixer
There is a butterfly-like icon on the'Mix' track on the far right, so click that.
Now you can monitor all channels.
You can perform channel reassignment work from this track mixer, just like during sequence setup.
When you play it back, you can see at a glance which channel is assigned to what.

❹ Exporting

Did you think you could just export it as is?

Too bad! There's still another step! There are too many traps!

1. Select the sequence and enter export mode

2. Codec must be mov format (H.264 is not supported)

3. Scroll down to Audio > Audio Channel Settings

4. Click '+' to increase to 8 channels

5. Output channels... Change to 'Mono'

6. Press the Export button!

With this, you have exported a multi-channel video.
Sigh...
Adobe, can't you make this a bit more intuitive???