Safe to always use Dolby Pro Logic II, even for stereo?

[nawoa]

The way I understand DPLII, it acts sort of like joint-stereo MP3 encoding, where a portion of one audio channel is used to create another channel. This is why it's detected as stereo when it is actually specially-encoded 5.1. But if there's no rear channels to mix in and LFE isn't currently working in HandBrake, does that mean it's safe to just use "AAC (ffmpeg) | Dolby Pro Logic 2 | Auto | 256kbps" as my default setting even when the source material is plain 2-channel stereo? Or would this degrade the audio in some way?

I'm trying to create settings that I can use with minimal adjustment 99% of the time. If I could just select DPLII as the default for any number of channels, it would simplify things a lot.

Thanks!

[Deleted User 13735]

Dolby PL II and Joint Stereo are different methods used for different purposes.
For any stereo source or mixdown, PL II is just fine for general use; it does not color the stereo output save for an imperceptible phase shift.
PL II is not used for Digital Surround (5.1) output, nor does it encode existing discrete Rear/LFE channels for later use.

[Deleted User 11865]

Also, libhb will automatically sanitize DPL2 to Stereo if the source is Stereo.

[nawoa]

PL II is not used for Digital Surround (5.1) output, nor does it encode existing discrete Rear/LFE channels for later use.

If you're right, someone needs to do some wiki editing:

Wikipedia entry on Dolby Pro Logic:

Dolby Pro Logic

Dolby Surround/Pro Logic is based on basic matrix technology. When a Dolby Surround soundtrack is created, four channels of sound are matrix-encoded into an ordinary stereo (two channel) sound track. The centre channel is encoded by placing it equally in the left and right channels; the rear channel is encoded using phase shift techniques, typically an out of phase stereo mixdown. A Pro Logic decoder/processor "unfolds" the sound into the original 4.0 surround—left and right, center, and a single limited frequency-range (7 kHz low-pass filtered[1]) mono rear channel—while systems lacking the decoder play back the audio as standard stereo.

(...)

Dolby Pro Logic II

In 2000, Dolby introduced Dolby Pro Logic II (DPL II), an improved implementation of Dolby Pro Logic created by Jim Fosgate. DPL II processes any high quality stereo signal source into five separate full frequency channels (right front, center, left front, right rear and left rear). Dolby Pro Logic II also decodes 5 channels from stereo signals encoded in traditional four-channel Dolby Surround. DPL II implements greatly enhanced steering compared to DPL, and as a result, offers an exceptionally stable sound field that simulates 5 channel surround sound.

(...)

Software encoding/decoding

The liba52 decoder library for AC3 and A52 digital sound optionally exports stereo sound compatible with Dolby Surround and Pro Logic.

HandBrake is capable of downmixing Dolby Digital AC-3 5.1 to Stereo for Dolby Pro Logic I & II for surround playback.

Handbrake Wiki > Audio > Guide to Surround Sound in HandBrake:

HandBrake offers several surround options depending on your uses.

The simplest method is using Dolby Pro Logic II. This is the default behavior for HandBrake. If you feed HandBrake an Dolby Digital AC3 or Digital Theater System 5.1 sound track and tell it to convert using AAC, it will default to converting or "downmixing" the track to Dolby Pro Logic II in an AAC track. This will sound fine on both stereo and surround audio systems and will play in pretty much anything. If your DVD already contains Dolby Pro Logic audio, also known as Dolby Surround, it will be preserved. If you wish, you can use Dolby Pro Logic I instead of II, by selecting "Dolby Surround" from the Track Mix drop-down menu. Be aware that, due to technical concerns, Dolby Pro Logic II is currently created as 5.0 sound. This means there is no separate subwoofer channel. Adding the sub channel can cause serious distortion, depending on how the DVD's audio was mastered.

[Deleted User 13735]

PL II is not used for Digital Surround (5.1) output, nor does it encode existing discrete Rear/LFE channels for later use.

If you're right, someone needs to do some wiki editing:

"Dolby Surround/Pro Logic is based on basic matrix technology."

And there you have your answer in the first sentence of your quote. The rest merely underscores my point.
Wikipedia does not need editing on this topic, nor do I. I'm really pretty careful about using precise language in my responses.
Perhaps you would want to undertake a basic learning adventure in order to discover the differences between the two technologies for yourself.
Best of luck.