AC3 newbie question

[bob_the_mailman]

Hi

Firstly as far as AC3 is concerned I am a newbie. For Video I am more advanced.

I have downloaded a Divx file and GSpot mentions the audio has AC3(???).
I can play the movie, so I obviously have the correct audio codec.
What does AC3 mean ?
Is this surround sound audio ?

or plain old stereo versus 5.1

If this information is in a guide on this site somewhere, directions to that guide would be appreciated.
thanks

[mysticgohan17]

in most cases its Dolby Digital 5.1, in others its DD 2.0

[Rickster]

Specifically, AC-3 stands for "Audio Coding 3" and is the third audio compression format developed by Dolby Labs. It is designed to handle multi-channel audio formats with data rates ranging from 32 to 640 kilobits per second per channel (depending on the application).
You may want to check your audio codecs in your control panel on your computer to see if you have the AC-3 codec. As far as I know, there is no DIVX video that is streamed or can be downloaded on the net that has AC-3 audio. It seems to be misunderstood, even by the studios releasing movies on DVD. Take the low-budget movie "Oxygen" available now on DVD by Ardustry Entertainment. The back of the DVD boasts that the audio is in Dolby Digital 5.1 Stereo. See what I mean? You can Dolby Digital 2.0 Stereo, but not DD 5.1 Stereo.

[Hercules Man]

Yes you can have dd5.1 in divx, i have a few, use virtual dub to see the audio attributes, the ones i have converted to dvd have audio info as tag2000, which had 5.1, i ripped that out using direct stream copy, save wav, then i put it through besweet which gave me a true 5.1 dd audio file

Hercules Man

[bugster]

@Rickster, as Hercules Man says, some divx movies do have Ac3 audio and yes, it often is the full 5.1 channel soundtrack from the DVD.

I agree that the description from a DVD you give is confusing, DD 5.1 is not stereo, but 5.1. However, it is a requirement of all DVD players that support Ac3 audio (and I believe it is mandatory that they do so) to be able to downmix 5.1 soundtracks into a stereo soundtrack. You won't get the surround sound effects, but you will get full stereo sound. It is also often the case that when this occurs, the older analog Dolby surround info is available in the analog stereo output by this process, so if you have an old dolby surround decoder you can still get surround sound (though it is not as good as DD 5.1!)

@bob_the_mailman, there is an Ac3 codec available in the tools section of this site.

[Mont]

Yes you can have dd5.1 in divx, i have a few, use virtual dub to see the audio attributes, the ones i have converted to dvd have audio info as tag2000, which had 5.1, i ripped that out using direct stream copy, save wav, then i put it through besweet which gave me a true 5.1 dd audio file

Hercules, what were the settings you used. I'm trying to do Pal 25>NTSC 23.976

[Hercules Man]

Can i ask you why you need to got to 23.976 ntsc film, awefull frame rate


Hercules Man