DCP specifications for film festivals may specify that the DCP should have at least an LCR mix with dialogue in the center channel.
If the dialogue is in the left and right speakers, the dialogue sound like it comes from the left side if you sit on the left side of the auditorium, and the right side if you sit on the right side.
Upmixing to 5.1
Add a stereo sound track. You can drag the video or an audio track.
Upmixing with the DTS neural upmix plugin
- Click on the sound track
- In Inserts – Choose Multichannel plugin – sound field – DTS neural upmix (stereo 5.1) insert.
- Say yes when Pro Tools asks you if you want a 5.1 output
- In I/O Choose – output – 5.1
Click on the soundtrack and play. You can now see how the mix looks after the plugin upmixes it to 5.1
For a typical upmix I use the auto width and depth settings and lower the LFE by -7.
Bass management can also be turned off for a safer upmix.
The DTS upmix plugin uses similar phase algorithms as Dolby Surround/Prologic on a Dolby processor to make the surround channels and center channel. But instead of a low pass of 120 Hz to the LFE channel, the default is 80 Hz.
Upmixing to LCR
When doing a Left, center, right (LCR) mix, I turn the Bass Management off and slide the Depth slider all the way to the front. A LCR upmix is the safest choice.
To save the 5.1 mix, I use Bounce mix. On SSD disks, it is around 40x speed.
-Click on the sound track
-File – Bounce mix
Mix Source 5.1 (5.1)
File format: Multiple mono
Bit Depth 32-bit float
Sample rate 48 kHz
Optional: Pad to Frame Boundary
Installing a virtual 5.1 sound card
Choose asio4all in Setup – Playback engine
In I/O setup make sure you have a 5.1 path.
Start a new project
I/O settings 5.1 Film Mix
Sample rate 48 kHz
Bit depth: 32-bit float
The center channel is important for dialogue in cinemas
Cinemas have always used a center channel for dialogue.
At first, cinemas had mono sound in a center channel.
Then Dolby Stereo in the 70 and 80s used 4 channels extracted from the stereo track: Left, Right, Center, and Mono Surround.
Then 5.1/6.1 Dolby Digital, DTS, and SDDS in the 90s used discrete Left, Right, Center, LFE, Ls, and Rs channels with varying degrees of compression.