How to make a 2.1 OGG or AC3 file? [Archive]

View Full Version : How to make a 2.1 OGG or AC3 file?

Nemesis7

14th November 2002, 21:56

How do I make a 2.1 (meaning, center spreaker output, with the rest downmixed to stereo,or surround2) out of a 5.1 AC3 track??
I prefer to have this done with a OGG file, but Ac3 would be fine too.

So what EXACT settings must I have in OGGMachine or AC3Machine?

All this,IF its possible, maybe is the thing I mean 2.0 or 3.0 or 3.1 Ac3,but I'm not sure.

Thnx.

stargazer

14th November 2002, 23:41

I think 3.0 is correct designation (3 = 3 separate channels<L C R>, 0 = no separate LFE).

I have the same problem, only I want 4-channel ogg (4.0) and I can not find any way to create it in OggMachine (there are only stereo, surround, surround2 and 5.1 options). AFAIK, these are restrictions of BeSweet, so different settings than mentioned are not available.

You can make multichannel ogg using HeadAC3he, simply by putting a check mark in desired output channels.

Tip: Audio encoding section would be maybe a better choice for this thread.

Nemesis7

15th November 2002, 02:24

True, that I can make that with HeadAc3he, but if i select L,C,R what happens to the other 2(rear), will they be mixed into the L and R ones? And if I make a 3.0 OGG file, how ill I be able to play it correctly??

P.S. Thanks for the tip, can some1 move this thread to the audio section or do I have to post a new one?

RadicalEd

15th November 2002, 02:39

hmm.. cool, so I'm guessing HeadAC3 could output real 2.1 audio (L, R, and LFE) to use with my 2.1 speakers
although my soundcard only outputs stereo, it would still be cool :D

Nemesis7

15th November 2002, 09:09

I tried HeadAc3ahe, it doesnt support downmixing for more than 2 channels, :( , so is there no way to make a 3.0 audio file that works??, isn't it possible to edit the ac3, per channel? Like to mix the rear with the left and right and then put it back as L and R?

stargazer

16th November 2002, 00:08

Originally posted by Nemesis7
I tried HeadAc3ahe, it doesnt support downmixing for more than 2 channels, :( , so is there no way to make a 3.0 audio file that works??,
It depends on the output file format (most formats like mp3 are not supporting multichannel audio) - AFAIK, multichannel ogg is only possible output in HeadAC3he and it works (all sorts of channel combination (ac3-wav is maybe another solution?)

isn't it possible to edit the ac3, per channel?
You can decode separate channels in 6 mono waves, and then edit them, but I don't know how you can rencode it in 3.0 ac3 stream (maybe using Sound Forge Studio? I don't know much about this tool:(

Other possibility would be (I'm just guessing ;) ) , after decoding AC3 to 6 separate waves, to downmix RL i RR channels in L and R, then do the same thing with LFE. Then, you should generate (in some audio editor) 3 blank (zero) waves (exactly same lenght as original AC3). Last step would be to encode created waves (front speakers downmixed waves, center speaker and rear speakers/subwoofer using blank waves) in 5.1 AC3 with BeSweet. Then you can force 5.1 playback on your 3.0 system and you'll get exactly the same thing! :cool:

Disclaimer: This post is a pure guess and shouldn't be considered seriusly :)

Nemesis7

16th November 2002, 00:28

multichannel ogg is only possible output in HeadAC3he and it works (all sorts of channel combination

Well I tried OGG, and just 3 channels, L,C,R and then it gave that error (support for downmixing more than 2 channels isnt there yet..

@stargazer
Thanx for the tip! I will try it later. If somebody else tried that, please let me know.

stargazer

16th November 2002, 02:14

Well I tried OGG, and just 3 channels, L,C,R and then it gave that error (support for downmixing more than 2 channels isnt there yet..
?? I don't understand...
I've done many 4-channel (4.0) oggs with HeadAC3he and they work flawlessly in my OGMs...

Nemesis7

16th November 2002, 03:21

You probably selected the 4Ch mode.... hmm good point, I had it on surround2. Damn thats stupid. Thnx man.
So if this is done, how do I play it properly?? What player, hope there is a way to use it wth ZoomPlayer or WMP.

How much bigger will it b if I add the LFE ?? Does it take as much space as a single channel?

RadicalEd

16th November 2002, 04:38

my turn to guess, AFAIK LFE is, like the term 5.1 suggests, only 0.1 of the total bitrate. It seems a logical guess :/

but... hmm. This discussion makes me wonder, it should technically be possible to separate the different channels of the ac3... just like the thread awhile ago asking if it was possible to demux a stereo file to two mono files. I mean.. the actual compressed audio is separate and only joined by the ac3 container right? Unless some sort of cross-compression is used... but then that would just be like joint stereo on a 5.1 level. hmmm. Being able to demux into 6 separate channels would be beneficial since you wouldnt have to re-encode... anyone have any ideas or input? dspguru, any inside info?

stargazer

17th November 2002, 03:27

Originally posted by RadicalEd
my turn to guess, AFAIK LFE is, like the term 5.1 suggests, only 0.1 of the total bitrate. It seems a logical guess :/
AFAIK, you're wrong. .1 term is only there to make difference between "real channels" when positioning is considered, and LFE, that "gathers" low frequency sounds from ALL other channels (it would be complicated to have every surround speaker with subwoofer-like low frequency output capability - it is proven that human ear is very bad "perfomer" in low frequency sound positioning)

but... hmm. This discussion makes me wonder, it should technically be possible to separate the different channels of the ac3...
<cutted>
:readfaq:

RadicalEd

17th November 2002, 03:54

yeah, I read all the faqs and none of them said anything remotely pertaining to my ponderings
care to elaborate?

stargazer

17th November 2002, 10:35

RadicalEd

17th November 2002, 23:32

:p I know besweet can split a 5.1 channel ac3 into FL FR SL SR C and LFE wavs, thats not what I was talking about. I was saying it should be possible to do the above without decompressing to wav.

Originally posted by RadicalEd
it should technically be possible to separate the different channels of the ac3...
Being able to demux into 6 separate channels would be beneficial since you wouldnt have to re-encode.

stargazer

18th November 2002, 00:12

:p I know besweet can split a 5.1 channel ac3 into FL FR SL SR C and LFE wavs, thats not what I was talking about.
Sorry, my fault. My english is not so good, so I sometimes don't understand everything with the right meaning :) ;)
I was saying it should be possible to do the above without decompressing to wav.
I've never heard for a way to split any compressed audio format to separate channels without de/recompressing.

RadicalEd

18th November 2002, 01:22

Yeah I've never heard of a way to do it yet either, but you'd think it would be possible. I mean, the channels are still separate inside the ac3 container.
hmmmmmmmmmmmmmmmmm
still waiting for dspguru to make an appearance

Nemesis7

18th November 2002, 03:07

cut&paste

8. What are the output formats offered by BeSweet ?
Mpeg - MP3,MP2,MPA.
AC3 - 2.0AC3, 5.1AC3, DolbyDigital WAV.
Ogg - Stereo, 6Ch vorbis.
AIFF - 5.1AIFF, 5.0AIFF.
WAVE - Stereo, 16bit WAV. Multichannel 5.1, 16bit WAV. 6 Mono WAVs.

So BeSweet can convert 5.1 Ac3 to 2.0 Ac3 ?? Without decoding and then re-encoding?
An a question about 2.0 Ac3, I had the Ring(u) DVD, and there were only 2 channels (sure of it), but the diaglogs came from the center and the rest of the sound from the other four. Can BeSweet do the same?

And yea, can't we notify dspguru somehow?

RadicalEd

18th November 2002, 03:47

1. nah, it decodes and then re-encodes.
2. probably pro logic

Nemesis7

18th November 2002, 15:11

wouldn't it need a encoder to do that? If so, why cant we use it,juts like we make ogg files, but make our own ac3 files, would be master. I mean this way I could make me a 3.0 file. Right?

RadicalEd

18th November 2002, 21:38

see that ac3enc.dll in the besweet directory? guess what it does ;)
we can make our own ac3 files just like ogg and you could make that 3.0 file. It'd still be re-encoding, so its not like you'd want to go 5.1 ac3 -> 3.0 ac3 -> 3.0 ogg but indeed you can encode ac3 and whether or not you do, well its just your call as to which format you'd rather use.
Isn't besweet great? :D

Nemesis7

19th November 2002, 05:33

Wow, damn i didnt see that.
So can I make the ac3 (3.0) with headac3he or other program? How do i do this? I already have the L,RL,LFE as LEFT and the R,RR,LFE as RIGHT and the C as CENTER. So how do I mux these these as a 3.0 Ac3 file?

Thnx for ur replies.