AC3 core, or downconverting Dolby True HD?

[bagmand]

Hi,
I'm backing up my bluray collection, to 720p mkv with dts core or ac3 "core" depending on whats avalible on the source!
It works fine, but it sounds, on my sound system, like dts core is alot better than ac3 "core". Much more depth and "surround fx"
Ac3 core sounds much more "simple" and "narrow".
My question is: should I transfer the Dolby true hd track, when ripping, and afterwords convert it to ac3 5.1 640kbs in, let's say handbrake, or doesn't it make any difference to letting, let's say, makemkv do the extracting of the Dolby True hd track to ac3 "core" on the fly, when ripping? A movie like Transformers 1 with ac3, sounds no way near the dts core track, in Transformers 2! But on bluray.com, Transformers 1, gets 5 stars on the audio track?
I know that dts core is 1509 kbs, vs. 640 kbs, but there shouldn't be such a big difference?
Hope you guys understand my question?

[sneaker]

Perceived audio quality is a lot more about psychology/marketing than about real differences. If the reviewer likes the Transformers 1 soundtrack better than the Transformers 2 soundtrack it's not about DTS vs AC3. For example humans think "loud=better". I'm betting in a proper blind listening test (ABX test) you won't be able to hear any difference between TrueHD and the corresponding 640 kbps AC3 core. Supposedly the commercial AC3 encoders (used for commercial Blu-Rays) are better than the free ones included in HandBrake/ffmpeg, anyways. So my advice would be to simply get the AC3 core via MakeMKV from the beginning.

[bagmand]

Thanks a lot, and for the fast response!
Then I will just continue my process

[Cornucopia]

One difference you should understand is that DTS is actually a true “core”, in that there is a standard DTS stream with an accompanying Enhancement stream which, when combined, create the lossless DTS.
Whereas with Dolby, the lossless portion is standalone and the so-called core stream is just a supplemental stream added for backward compatibility purposes. You can see this by comparing file sizes.
Why did they do it that way? Simple, DTS had the benefit of learning from Dolby as they didn’t put out their lossless solution until later, and Dolby also originally didn’t create their lossless solution - they bought it from Meridian (“MLP”) and modified it to work within the AC3 bit structure (as well as adding features to make it applicable to more platforms and use cases).

This difference may change how you decide to extract your chosen stream.

Scott

[babygdav]

Dts is using far more bits than ac3, thus able to sound better.

Without going into technical specifics,
Take your dts track using about 1500kbps. For 5.1 audio, let's simply say it's 5 channels of independent sound. 1500/5=300kbps.

640kbps ac3 / 5 = 128kbps.

Can people hear the difference between 320 and 128kbps mp3 files? Absolutely. Ditto with dts vs ac3.

[johns0]

Unless you have an uber audio system you won't hear the difference as long as both sources are studio produced.

[chopchopOverTheTop]

Thank you Audiophiles for making me think I am missing out on something I can't hear anyway(I'm old). I'm about to do a few tests myself but does anyone have any results on storage space saving/quality gains with the aforementioned technologies/processes?