Downmix to Stereo

Tech198

macrumors G5
Original poster
Mar 21, 2011
14,057
1,668
Australia, Perth
Hi all

Having a few DVD's with handbrake, the audio is down mixed to "Dolby Pro Logic II" and not "Stereo" which i always make sure i select regardless, so i have play the resulting m4v file handbrake produces, from my iTunes library on Apple TV.


I've had issues previously, if left, where by i hear like a "butterfly' effect, where the previously audio dialog is always present even with the current audio. This is played back to a Toshiba LCD via through standard internal speakers.

Should i down mix to stereo, or is Dolby Pro Logic ok for this setup ?

As all my content i make sure is Stereo, but not releasing i may have made a mistake.
 

CptSky

macrumors regular
Feb 1, 2013
140
13
I'm not sure if Handbrake will properly down mix a better-than-stereo source to stereo correctly. Dolby Pro Logic II is a stereo matrix of the original source, and can be decoded to the original source with a proper decoder (or will be detected as stereo by others). I think for stereo, Handbrake will just recopy the L & R channels, without matrixing ?
 

westrock2000

macrumors 6502a
Oct 18, 2013
524
22
Is it possible that whatever device is producing the sound that it is set to automatically switch to DPLII? On my receiver, if I do not explicitly tell it to play a source in stereo it tries to go to whatever the best surround sound format is, which for stereo source is DPLII.
 

dynaflash

macrumors 68020
Mar 27, 2003
2,119
5
Should i down mix to stereo, or is Dolby Pro Logic ok for this setup ?
Use DPL2. Both are two channel but DPL 2 uses phase shifting so that in a surround sound environment you get a 5.0 surround effect but it still sounds normal on a two speaker setup.

Yes, I said 5.0 as the DPL 2 spec says that the LFE channel is not produced in phase, but I digress.

So in short ... if your dvds have AC3 5.1 sources (which all I believe do) then use DPL2 which is default for HB. Why would you want to lose the upside of the DPL2 surround effect ? Like I said no downside on a 2 speaker setup.

Edit: Most dvds have 5.1 AC3 the exception would typically be older concert footage where it was originally recorded in Stereo.

Here is more reading re DPL2 http://www.dolby.com/us/en/consumer/technology/home-theater/dolby-pro-logic-ii-details.html
 

waw74

macrumors 68040
May 27, 2008
3,173
194
or leave it in dolby digital surround, let your TV (or media player) do the downmix. And in the future, if you upgrade your audio system, your files are ready.
 

westrock2000

macrumors 6502a
Oct 18, 2013
524
22
So in short ... if your dvds have AC3 5.1 sources (which all I believe do)
Ya, you gotta love Gone With The Wind in super awesome 5.1 surround sound :rolleyes:

I do get some older 70's & 80's movies, especially foreign films that only have 2.0 stereo. I keep them as stereo, and kick up the bit-rate to 256 or 320 instead of the normal 160 AAC + 640 AC-3 I normally do.

I don't think I have yet to get a Blu-ray that only had stereo.
 

westrock2000

macrumors 6502a
Oct 18, 2013
524
22
I believe I edited my post to reflect *most* dvds. C'mon man :)
Sorry, looking back I can see how you mistook that :)

What I meant was that Gone With The Wind a film made in 1939 and filmed in mono, comes on DVD as 5.1....to which I say :rolleyes:

That's to say I was agreeing with you.