AC3 5.1 or AC3 Dolby Surround

[THRobinson]

Hey guys, quick (I hope) question here....

When I convert videos with DTS, I convert the DTS down to AC3 5.1 (640kbps) and overall save as an MP4.

Noticed the other day (using VidCoder by the way) if I click AC3 Dolby Surround, it saves even more space (when bitrate set to auto... 224kbps I think).

I searched online to see which I should use, and seems from what I found, when people ask which is better the response is often that AC3 5.1 uses 6 channels, and AC3 Dolby Surround uses 2 channels and I guess matrixes in the remaining 3.1 info... something along those lines. Good info, but not really an answer regarding which is better, or if close enough to being the same most won't hear a difference.

Right now, I have a computer running KODI/XBMC through a Sony Bravia using the TV speakers... so nothing at all elaborate. Same time, I don't want to shoot myself in the foot and 6 months from now buy a good sound bar or full 5.1 setup and be annoyed at converting one way instead of the other.

So... average joe user, converting DTS5.1... should I stick with AC3 5.1? switch to AC3 Dolby Surround and save a bit of space? or option 3?

MP4 or MKV isn't an issue... media server plays both... I know if I passthrough DTS it recommends MKV... but drive space is a concern for me. I try to convert at around 4000kbps 2-Pass for video and keep the files under 4GB. Hence converting DTS down.

Thanks for any feedback.

[JoeS99]

Well Gee, some people might think you'd be sorry for not keeping the DTS, since it theoretically has more dynamic range than AC3. It all depends what you will ultimately want. If you get a full 5.1 channel sound system someday you will probably be happy you had the foresight to save your files with AC3 5.1 .

[Brad]

A difference of 416kbps is a concern for hard disk storage in 2015?

[THRobinson]

Ya keeping DTS is ideal, but not when saving space. Ideally I'd also not compress the video file down below 4GB.

But, been happy with the video quality so far... audio as well though only using TV speakers. I don't know if I'd ever get 5.1 in the future, definitely want a 2.1 sound bar though for that extra bit of quality and bass. I'll keep it at AC3 5.1 since it's been working.

416kbps wise... Not much of an answer to the question being asked... I simply said it saved space... if the general consensus was that AC3 Dolby set to auto for bitrate was just as good as AC3 5.1 then saving some space means I can use a higher bitrate for the video. Not sure why auto drops it to 224kbps, and why AC3 5.1 defaults to 640kbps, but not really the point of the post.

[Cornucopia]

Matrixed surround (such as Dolby Surround/ProLogic/PL2) is good, and might be acceptable some of the time, but is NEVER as good as discrete surround (such as DD 5.1 or DTS 5.1). If you ever did a back-to-back comparison you ought to be able to tell the difference.

5.1 @ 640kbps = ~112-128kbps/channel (hard to calc, as less is needed for the 0.1).
"auto" Dolby Surround uses 2 channels. At 224kbps, that = 112kbps/channel.

5.1 AC-3 will auto downmix on live playback to 2.0 or 2.1 if that is the only output channels you have. The reverse with Dolby Surround is not necessarily true.

I would look at the option of keeping the DTS originals if you plan to ever get a playback chain which supports DTS.

One more thing: DS only matrixes in 4.0 or 5.0 channels (depending upon which version). NONE of them include the 0.1 channel - it is lost!

Scott

[THRobinson]

Well... again... DTS I know is better but, trying to keep the files under the 4GB size because of how many I have, and I'd rather have better video than sound... that being said, I don't want great video and crappy sound.

For now I'll stick with AC3 5.1 @ 640kbps... if I ever get the money for a 4x3TB raid setup... I'll redo the files.

Right now I have 2 3TB drives, one for movies, one for TV series... then an external 3TB drive for each as a mirror copy. Ideally I'd like 4x3TB internal as a RAID setup as 12TB (before formatted... probably closer to 9TB after formatted) and then an external box like a DROBO for a mirror backup.

[newpball]

Alternative is good old stereo.

I for one am seldom impressed by the surround mixes concocted by sound engineers.

[THRobinson]

Alternative is good old stereo.

I for one am seldom impressed by the surround mixes concocted by sound engineers.

I use to have a nice 5.1 setup years ago, but found myself spending more time tweeking and changing settings depending on which movie I was watching and spent less time enjoying the movie. When I downsized a bit to go back to school, I sold the system... been using the TV speakers (good ol' stereo) ever since and been mostly happy with the setup. I kinda doubt I'll ever go full 5.1 again, mainly because I hated the wires, having a receiver, and rear speakers in the way... likely I'll get a nice sound bar and sub combo and that's all. Still, never know... best to think ahead.

[Cornucopia]

Alternative is good old stereo.

I for one am seldom impressed by the surround mixes concocted by sound engineers.

There are MANY alternatives: ("good old") mono, stereo, binaural, 3ch-stereo, quad/DS, sonic holography, ambisonics, auro3D, dts : x, dolby atmos...
They each have their moments to shine.

Just because YOU are seldom impressed doesn't mean that most people aren't. You have quite a track record of "not-being-impressed".
And, just because you put stock in avoiding technologies that aren't your pet projects doesn't mean you should dissuade others from pursuing them.

I wonder: are sound engineers impressed by mixes concocted by you?

Scott

[pandy]

Go for lower bitrate and keep 5.1 (AFAIR maximum 'accepted' in TV broadcast bitrate for AC3 5.1 is 448kbps - 512kbps - lot of hw specifications didn't list 640kbps AC3)

[THRobinson]

I was debating that as well... 640kbps vs something like 512kbps... doesn't save lot's of space but again if allows me to bump up the video bitrate.

[fritzi93]

Doesn't DVD-Video use 448 kb/s for DD 5.1? I forget now. That's what I'd go with if space were a concern, but by all means keep 5.1. (I use DD 5.1 at 640 kbps in MKV for compatibility).

There's a 2.1 soundbar in our living room that replaced a 2.0 soundbar. For some movies, it makes quite a difference.

IMO, a 5.1 setup is well worth it. But I wired up the HT when doing the remodel. It's more of a job as a retrofit, unless you're okay with wires everywhere, so yeah, there's that.

Sure, with a lot of movies, you'll only get a bit more "presence" with 5.1. But when you a play a movie with a mix fully deserving 5.1, it's a whole different experience. Like the movie "Rush", with formula one cars moving across the 3 dimensional field.

Personally, I'd hate to think of having to do my Blu-Rays over again at this point. You may have a 5.1 setup in the future.

Good luck.

[THRobinson]

Dolby Digitial 5.1... hmm...

DTS for me is just too big a file and likely overkill for someone like me given my current and planned audio setup.

I am open to an Option #3... AC3 5.1 I saw mentioned online often so kinda gravitated towards using that vs AAC or anything else. But if there's an option as good or better at around the same size, I'll switch.

Sound wise, last 2 apartments I've been in, the sofa's been up against the wall in front of the TV... my rear speakers would be a foot away from my head beside me so, doubt the best setup... that's why I'll probably get a sound bar, and likely a Sony because my TV is a Sony and I guess they can 'talk' to one another.

[smitbret]

DVD standard is DD5.1 @ 448Kbps

More bitrate is always better but if you've been happy with the way DVDs sound on your surround system, then that's the direction I would head. Forget the Dolby Surround, it's simulated surround and akin to using a soundbar instead of a proper surround sound system. If space is your primary concern and your hardware supports it, just convert DTS to AAC 5.1 instead of Dolby Digital. It is a better compression scheme but much less widely accepted in the HT arena.

[newpball]

...it's simulated surround...

As is most other surround!

"surround sound" is almost always a bunch of mono and stereo tracks panned and processed into the separate channels.

You did not really think they put 5 phase correct directional mics around the scene right?

Because in that case I have a bridge for sale:

[smitbret]

...it's simulated surround...

As is most other surround!

"surround sound" is almost always a bunch of mono and stereo tracks panned and processed into the separate channels.

You did not really think they put 5 phase correct directional mics around the scene right?

Because in that case I have a bridge for sale:

You know what I meant and if you didn't/don't then you probably shouldn't be posting in these threads.

[newpball]

You know what I meant and if you didn't/don't then you probably shouldn't be posting in these threads.

Well I am sorry for over reacting, "surround sound" is one of my hobbyhorses.

[smitbret]

You know what I meant and if you didn't/don't then you probably shouldn't be posting in these threads.

Well I am sorry for over reacting, "surround sound" is one of my hobbyhorses.

Your avatar looks cranky and drew an aggressive response.

[Cornucopia]

Yet one that you seem to know very little about, as you keep spewing antiquated info, disinfo and FUD on the topic.

You talk glowingly about "good old stereo", yet fail to recognize that most pop recordings are also generated from multiple mono - not as a "cheat" but in order to avoid noise buildup and to avoid acoustic mismatch while maintaining exact placement. And you do not consider them "simulated".
And then you ignore the fact that there ARE many surround recordings that ARE phase-accurate - both from grouped-source-microphone workflows, and from physics- and HRTF-based insertion of multiple-mono sources.

Thing is, none of those are "simulated" methods. Some are "formalist" and some are "realist" (and a few are formalist+realist). Even matrixed surround isn't "simulated", just more quasi- than it's discrete siblings.

I know, how about you start another poll to debate this!!??

Scott

[newpball]

You know what I meant and if you didn't/don't then you probably shouldn't be posting in these threads.

Well I am sorry for over reacting, "surround sound" is one of my hobbyhorses.

Your avatar looks cranky and drew an aggressive response.

Yes, I will change the avatar shortly.

[THRobinson]

So... DD... I have Dolby Surround and Dolby Pro Logic... what's DD? I assume Dolby Digital, is that DTS?

[JVRaines]

DD = Dolby Digital = AC-3
DTS is a competing compression technology.

[fritzi93]

Dolby Digital is AC3. Same thing.

[THRobinson]

Ah, gotcha... was looking through my audio options in VidCoder trying to find something that matched DD.

Thanks for the info guys!

AC3 5.1 @ 640kbps is what I'll stick with. Maybe DTS for a few of the movies that deserve better like Guardians of the Galaxy... some movies like Dumb and Dumber, great movie, but doubt much benefit to having a bigger audio track.

[fritzi93]

Not to re-start the DTS vs AC3 debate, but AC3 (DD) 5.1 is fine. People automatically assume DTS is far superior.

Often times I've ripped a BD with DTS and compared my re-encode with AC3. Yes the dynamic range is different (one effect of which is the DTS stream will be louder at the same volume setting). I can distinguish subtle differences between the two (besides volume) when playing each one back to back. But I doubt I could reliably identify it if playing just one or the other without knowing beforehand which compression was used. Maybe someone with "golden ears" and better equipment can, but I can't. I have decent gear but not audiophile quality, which I fear would be wasted on me.

Anyway, I use AC3 for compatibility with all my devices. And BTW, my TVs will output AC3 5.1 over optical, whereas DTS will be output as stereo LPCM. Which may be a factor for you if you intend using a 2.1 soundbar.

Good luck.