AC3 - 2ch in XviD file ...... is it worth it?

[ripper2004]

I am doing XviD conversion of a 2.5 hr movie to a 1400MB AVI file.
My DVD has AC3-2ch audio in it. I think AC3 has all the surround effects and 3d audio stuff .. that i dont wanna lose. But does the 2-channel AC3 have all the good surround stuff and all?
Is it worth the extra space at all?

I was thinking ... if instead of AC3 and use VBR MP3 192/160 instead, i might improve the video quality a bit more.

We sometimes have AC3-6ch too. I think that shd be more worth and am definitely gonna keep AC3-6ch.

Thanks.

[teegee420]

You won't be getting a surround effect with 2 channel ac3.

[FulciLives]

2.0 AC-3 is usually 192kbps, 224kbps or 256kbps with 192kbps being the most popular.

So I'd say keep it.

You gain NO SPACE at all by converting 192kbps 2.0 AC-3 to 192kbps MP3 audio and in my opinion the lowest bitrate for good quality MP3 is 192kbps so ...

There you go.

As for 224kbps or 256kbps ... well you really won't gain much by "downsizing" them to 192kbps MP3

So it's not worth it.

In short ... keep 2.0 AC-3 audio

5.1 AC-3 can be rather large though but I would still keep it especially if you are doing 2 CD back-ups. That should give you enough video bitrate even with high bitrate 5.1 AC-3 audio.

- John "FulciLives" Coleman

[ripper2004]

If there are no "effects" in AC3-2ch....So i can safely use VBR MP3 192/160 instead of AC3-2ch then.

i also heard that with VBR there are problems like losing audio sync when the file is split etc.

Is it really true?

[teegee420]

If it were me, I'd leave well enough alone and just keep the ac3. The VBR MP3 audio a/v sync problem only becomes an issue when you are converting from avi to mpeg.

[ripper2004]

It was a 2.5 hr movie trying to fit in 1400MB. so was trying for may be an extra 20 pixels in resolution.

Thanks .. i will use AC3.

Thanks again for the lightning fast replies !!!

[Skynet107]

There are surround effects in AC-3 2 channel providing the soundtrack has dolby surround matrixed into the audio. ANY stereo audio source can have dolby surround because the surround effects are embedded in the analog domain and extracted by phase detection.

And I agree keep the AC-3 sound DD2 channel easily sounds as good as mp3 at the same bitrate IMO.

[Shudder]

there is absolutely no reason to sacrifice audio quality (and why would even consider ruining an already good ac3 file to make an inferior mp3?) for a VERY SLIGHT video increase. If you went from 192 ac3 to 160mp3 you'd not only degrade the sound quality, but the space difference is like 20 megs.. For roughly 1250 megabytes of video, do you think degrading sound to add 20 megs to video is worth it? Nah.

Plus to make a dvd out of that xvid, ac3 would be better suited.