WHY NO Ac3 below 224kps?

[00diabolic]

Hi

I have been encoding my moviez with mp3 audio for as long as I can remember. I know all the tricks when it comes to video. Yet audio has always been mp3.

Recently I got ahold of a movie and was shocked that the audio was ac3 and file size was still normal. I figured ac3 had to be huge cuz thats whats on dvd's. So I started testing and found ac3machine, ac3enc.dll, and besweet (which I have used with gknot before) and discovered I could make an ac3 that was 128kps and was the exact same size as my audio in 128kps mp3 format. That blew my mind. 5.1 Ch 128kps audio same size as mp3 2 ch.

In the ac3machine guide it says "Set whatever bitrate you see fit. Going below 224kbit/s for a 5.1ch AC3 doesn't make much sense and going above the input bitrate doesn't make any sense either."

Then I read the above. Yet At 224 that audio was twice as big 220megs, no good. 128 same size as my Mp3 @ 128 (around 125megs).

So my question is this. Is ac3 5.1 128kps audio better then mp3 2ch 128kps audio that I have been using for years?

I have a 5.1 ch system and from what I can hear the 5.1 sounds good in 128kps except for a lil hiss. So what am I missing. Is it better quality then mp3 or not?

Would that ac3 encoded to 128kps be better with a different encoder?

Ac3machine uses the ac3enc.dll and I know that its not as good as other encoders. Can I use the sonic foundry soft encode dll with ac3machine, and how would I do that? or do I have to use soft encode to do it all? Soft encode is slow, is there a fast way to encode with ac3machine and not use the ac3enc.dll?

Any suggestions would be helpful. I know that both AAC and mp3 both have 5.1 surround options, yet I have not used them. Would using one of them result in a file around 125megs.

THANK YOU

[E-Male]

at the same bitrate any audio ( or video) of a certain length has the same size, no matter what codec

ac3 5.1 at 128kb/s sounds crazy to me

if you want 5.1 at lower bitrates then ac3 (from dvd) you should try he-aac

about what is better: do you want discrete 5.1 or is stereo/pl2 enough, answering this you can answer your own question

if you want fast high quality encoding get encoding hardware *j/k*

[BigDid]

Originally posted by 00diabolic
...Then I read the above. Yet At 224 that audio was twice as big 220megs, no good. 128 same size as my Mp3 @ 128 (around 125megs).

So my question is this. Is ac3 5.1 128kps audio better then mp3 2ch 128kps audio that I have been using for years?

I have a 5.1 ch system and from what I can hear the 5.1 sounds good in 128kps except for a lil hiss. So what am I missing. Is it better quality then mp3 or not?...
Hi 00diabolic and welcome to the forum,

I had a looooong argument on another forum with kurtnoise, the author of Belight, about ac3 encoding. I would prefer he or other techies to give you technical elements.

Tip: use your ears, listen, compare and stay with what suits you.

Another tip, in Belight a GUI for Besweet, the 2ch ac3 encoding begins, in the presets, at 256Kbps; for 5.1 it begins at 384 kbps.

If you don't need audio compatible with standalone players (SAP) you have other choices like AAC or OGG. Use the search function in the forum to gather infos on these subjects :)

You can fetch Belight here: http://corecodec.org/projects/belight/

Did

[SeeMoreDigital]

Originally posted by 00diabolic
...WHY NO Ac3 below 224kps? Because it would most likely sound like crap ;)

[00diabolic]

Thanks for all the info. ;)

-BigDid
I do have a 5.1 sound system that my computer is hooked upto. I use SPDIF optical to send the audio to my speakers from my audigy card. I do not have a standalone player but would like if could one day play my stuff on one. I did get one of my family members a Phillips DVP642 and I guess it would be nice if the stuff played on that also. I'm guessing AAC 5.1 would not play on that standalone player? But would play with all 5.1 channels encoded in AAC over my 5.1 speakers? Also if I used sonic foundry soft encode (which I have) and did a 128 of the ac3 that would make no difference. Basicly its a AC3 limitation not the encoder. RIGHT? AC3 can't go below 224kps.


-E-Male
Even if there are more channels this holds true?
"at the same bitrate any audio (or video) of a certain length has the same size, no matter what codec"

Where can I get he-aac? Does it encode as fast as say an mp3? IS there a mp3 surround program yet? One that can do mp3 in 5.1? I heard there was a codec but don't know about the program yet.

-SeeMoreDigital
HA HA.. but I'm starting to think your right. This 128 does sound BAD.. :p

[E-Male]

i know of ac3 192kb/s stereo tracks on official dvds
and of peopel using 160kb/s ac3 stereo, but i wouldn't

there are filters that allow realtime ac3 encoding so while playing your aac 5.1 track is converted to work with your amp

a bitrate is in kb/s, that's kilobytes per second
filesize (in kb) = bitrate (in kb/s) * length (in seconds)

[00diabolic]

After some finding.

I did find oagmachine and I'm about to do a 5.1 aac or ogg. Gonna try both.

The problem is this line now makes me wonder.

"Keep in mind that you'll need a soundcard with an analogue 5.1 channel output to use 5.1ch AAC/Vorbis"

Why do you need a analogue 5.1 output for it to work. My card does have a 5.1 analogue output but I use digital output. So basicly I'm screwed and if I do this 5.1 ogg or AAC it will play as stero.

What filter allows for realtime aac 5.1 to ac3 5.1? You got a link?

THX

[E-Male]

this line is outdated

http://ac3filter.sourceforge.net/download/ac3filter_1_01a_rc5.exe
http://acidbao.free.fr/isoft/dlpage.php?prog=DolbyOutDS

aac is considered better for 5.1 at lower bitrates than ogg, because of channel coupling