AC3 2ch vs LAME alt-preset mp3

[Vegeta]

Simple question, NO HATE replies, just simple opinions. It's always good to see a new thread of arguing and bickering every once in awhile, and I'd feel proud to have started it! LOL! :) So yeah, got a DVD...did --alt-preset normal...from a 448kbit 5ch AC3....bitrate ended up around 183kbit. Also have a 192kbit 2ch AC3 (Dolby Pro Logic I assume). Now in Exit Wounds, AC3 sounded much better because LAME made the bass too well, loud! In Pearl Harbor however, the 2ch AC3 sounded a bit more muted, and quiet (especially in a couple of scenes with people talking), than the 5ch ac3 or the mp3 encoded from that 5ch ac3. Most of the time however, 2ch AC3 is nice but so is MP3. So how about it. Let me have it, rip on me, hate on me, love me, whatever. Just give me some opinions! Thanks!!

[MxxCon]

if you have space keep AC3
otherwise make mp3
what else is there?

oh, and i think AC3 w/ bitrate of 192kbit is bad...don't remember where i read that. it must be 384kbit

[tangent]

Of course the original AC3 will sound better because there is only 1 stage lossy.

When you transcode from an AC3 to MP3, you can never get an MP3 with better quality than the AC3 even if you use higher bitrate, because now you have 2 lossy stages.

So there's no point transcoding from AC3 to MP3 unless you need a low bitrate below 160kbps, or the DVD doesn't have a 192kbps Dolby Surround AC3.


Otherwise, if you encode an original wav with both AC3 192kbps and LAME --alt-preset standard, you should get better quality with LAME.

[Rhaegar Targaryen]

As usual, you people have copy n' pasted your pathetic "follow the leader" response and not bothered to consider what this fellow is actually asking.

He is asking about the difference between the 2.0-ch 192kbps Dolby Surround(tm) AC3 file, and an "alt-preset standard" MP3 made from the 5.1-ch stream using the most advanced BeSweet/LAME techniques. Which is a perfectly valid question, because he is using a DIFFERENT SOURCE to make the MP3 than the AC3 file in question. It may have been processed different (for dynamics) and it may even come from a *different STUDIO MIX*. And some DVDs, which are re-issues of old movies, keep the old '80s mix in the 192kbps stream and put a new REMASTERED mix in the 5.1 stream. So USUALLY the 5.1 stream will sound better, even if it is LOSSILY COMPRESSED to MP3, never mind the fact that using BeSweet and Lame 3.91 with 24/32bit float intermediary files and NOT downsampling produces sound that is SO close to the original, I doubt any of you NON-audiophiles with sub-$10000 sound systems (more like sub-$200) could hear the difference.

</rant>

[western shinma]

But can you even use the alt presets with BeSweet? Last time I tried it with the modified DLLs supporting them, it didn't work because BeSweet didn't support using different values for -q, which is what the presets had been mapped to.

The same DLLs work fine in HeadAC3he however, which also fully supports floating point processing in recent versions.

[Rhaegar Targaryen]

The specifics of WHAT audio program works with 24/32-bit intermediary files and --alt-preset switches was not the purpose of my rant; it is a given that THERE DOES EXIST a way to utilize those quality-keeping methods, so it is irrelevant.

Mind you, I still use Headache with 16-bit WAV and "hybrid" scan mode for my AC3 decoding, since I don't watch my Divx files on my expensive HT setup - that's what I use to watch my DTS DVD's on.

[LotionBoy]

192 AC3 is is many cases a better sounding solution than any MP3 you can make. Why? Because for pretty much every recent Hollywood movie, the 2ch AC3 is professionally downmixed. Which means it is going to be mixed down better than Azid can do it. If the 5.1 is remastered and the 2 isn't, then you're probably better off downmixing the 5.1. If they are both from the same original track, the 2ch is better.

LotionBoy

[DSPguru]

Originally posted by western shinma
The same DLLs work fine in HeadAC3he however,check again..

[western shinma]

I haven't tested all the modes, but it certainly seems to be working. I tried DLL3 with quality set to 0 to activate the ABR alt presets. The file it generates is completely different than one with the regular 3.91 dll at the same settings, so it must be doing something.

Here's the bitrate histograms from EncSpot.

modified DLL:

32 0.0%
80 0.0%
96 | 2.5%
112 ||||||||||||||| 22.6%
128 |||||||||||||||||||||||||||||||||||||||| 59.7%
160 |||||||||| 15.2%
192 0.0%
224 0.0%

original 3.91:

-------------------------------------------
32 0.0%
80 0.1%
96 |||| 5.4%
112 |||||||||||||||||||||||||||||||||||||||| 54.0%
128 |||||||||||||||||| 24.3%
160 |||||||||| 14.1%
192 | 2.0%
224 0.1%