Handbrake Surround Question

[Hebriewyn]

I hope I am posting this in the right place. I've looked just about everywhere and haven't been able to find a good answer to the following question.

One section (https://trac.handbrake.fr/wiki/SurroundSoundGuide)on the says:

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.

So I have a DVD with two audio options listed: 5.1 ch & Dolby Surround.
If I do the 5.1 downmixed to PLII will all channels including the subwoofer be preserved or not?

If I choose Dolby Surround and "downmix" it to Dolby Surround everything is preserved and it will sound good in both stereo and surround, right?

[jbrjake]

It will not preserve the sub-channel if you do DD5.1 -> DPL2 because it can lead to interference. However, the reason it leads to interference is that LFE data is also usually present in other channels, so it's not like you lose all use of the subwoofer. If you do DPL2->DPL2 it will skip mixing down. Or should. Maurj, who wrote that code, has unfortunately been absent for quite awhile.

[Hebriewyn]

In your opinion, which do you think is better?

(AC3)(5.1 ch) --> DPL2
(AC3)(5.1 ch) --> Dolby Surround
(AC3)(DTS) --> DPL2
(AC3)(DTS) --> Dolby Surround
(AC3)(Dolby Surround) -->Dolby Surround
OR
Something Else

I would do the passthru, but I'm trying to cut down on the space that it takes up. Thoughts?

[Deleted User 11865]

There is no such thing as "(AC3)(DTS)". AC3 and DTS are two different audio codecs.

As for what's best, it depends on your playback software and/or devices. You could also encode to 5.1 (6-channel discrete) AAC if your receiver supports it, or if your playback software can convert it to 5.1 PCM (and your receiver supports 5.1 PCM).

[Hebriewyn]

Sorry, that was a typo on the (dts).

So in reading about DPL2 and Dolby Surround, am I correct in assuming that they basically do the same thing but that DPL2 does it better?

[Deleted User 11865]

Sorry, that was a typo on the (dts).

So in reading about DPL2 and Dolby Surround, am I correct in assuming that they basically do the same thing but that DPL2 does it better?

Correct. Some (much) older receivers may not be compatible with DPL2 though.

[Hebriewyn]

Thanks Rodeo!

I just wanted to check to see if some of the other things I've learned are true.

1. AC3 5.1 is better than DPL2 and Dolby Surround
2. DTS is better than AC3 5.1
3. Ripping from Dolby surround to dolby surround maintains everything.
4. Ripping from AC3 5.1 to Dolby Surround preserves all the channels.
5. Ripping from AC3 5.1 to DPL2 cuts the subwoofer sound.
6. On stereo or headphones, they will all sound the same.
7. On a low end speaker system, they will all sound the same.

Let me know if any of those are off-base.

[Deleted User 11865]

Thanks Rodeo!

I just wanted to check to see if some of the other things I've learned are true.

1. AC3 5.1 is better than DPL2 and Dolby Surround

Yes. AC3 and DTS passthrough do not re-encode the audio, so they're better than any other audio options.

2. DTS is better than AC3 5.1

If encoded properly, it's likely. DTS passthrough is only available in MKV, and your receiver has to support DTS.

3. Ripping from Dolby surround to dolby surround maintains everything.

No. The Dolby Surround information should be preserved (though we're not sure right now, the person who wrote the mixdown code can't be reached for clarification), but since you are re-encoding to a lossy format (AAC, MP3, Vorbis), you are losing some audio quality.

4. Ripping from AC3 5.1 to Dolby Surround preserves all the channels.

No. It preserves 4 channels (the LFE channel is cut, just like with DPLII).

5. Ripping from AC3 5.1 to DPL2 cuts the subwoofer sound.

Yes. The 5 other channels are preserved.

6. On stereo or headphones, they will all sound the same.

Yes.

7. On a low end speaker system, they will all sound the same.

Not sure what you mean by "low-end".

[Hebriewyn]

By low end, I mean a cheap surround sound set up. Like maybe a $200-$500 5.1 surround system you would get at a retail store like bestbuy.

[dynaflash]

By low end, I mean a cheap surround sound set up. Like maybe a $200-$500 5.1 surround system you would get at a retail store like bestbuy.

No, you can still hear the diffrence.