incorrect AC3's when decoding PAL DVD's

[Vosper]

This is my first post, but I've searched the forum at length for something relating to this.

Following Doom9's DivX5 guide, I've recently tried processing some Region 4 DVD's in DVD2AVI (on the way to using Gordian Knot for the encoding). So far I've tried Shrek and Highlander. In order to preview these (and presumably therefore to get the correct output) I have to switch into RGB mode. This seems a little unusual to me?
But the main problem is that when I have DVD2AVI demux the Dolby tracks, it produces only 2 channel AC3's from the 5.1 source. I know I have selected the right tracks, indeed when I have it demux all tracks, they all come out as only 2 channels.
I know I can use SmartRipper to demux the 5.1 tracks, but I'm still curious as to why DVD2AVI isn't working.

BTW I don't know whether DVD2AVI is simply naming the files wrong and they actually are 5.1 tracks, or whether they're 2 channel like the name suggests (a sample output filename is "highlander AC3 T01 3_2ch 448Kbps DELAY 8ms.ac3")

Any ideas?

[hakko504]

Originally posted by Vosper
BTW I don't know whether DVD2AVI is simply naming the files wrong and they actually are 5.1 tracks, or whether they're 2 channel like the name suggests (a sample output filename is "highlander AC3 T01 3_2ch 448Kbps DELAY 8ms.ac3")

Any ideas?
Don't worry, this is just a different notation for 5.1 sound, indicating 3 front channels and 2 back(surround) channels. I'm not sure, but I think that it does mean that there is no extra bass channel. (That would really make it 5.0 sound wouldn't it?)

[Vosper]

But when SmartRipper demux's the AC3 it calls it "vts_01_([0x80]_Audio_English_AC3(6Ch)_48kHz___)_Delay_8ms.ac3" indicating that there is (or should be?) a 6th channel. It seems odd to me that any DVD would be encoded in 5 channel AC3 with no LFE channel, since any home users with Dolby Surround setups are going to have a sub. And really, what movies have no LFE's?

Is it even a valid AC3 stream if it doesn't have an LFE channel? I've only heard of AC3 in 2 channel and 5.1 channel configurations.

[hakko504]

Like I said, I'm not sure if there is an LFE or not but a 5.0 config is valid, that I know. I also have a DVD with 4.0 sound (Runaway w/ Tom Selleck and Gene Simmons).

Why don't you dl Azid and force it to decode all channels to separate files? that way you can listen to the LFE separately and determine if it really exists or not. Azid will also tell you exactly which channels are present or not in the AC3 stream.

[kilg0r3]

btw is there any reason why one should not use the ac3 files extracted by smart ripper?

[A_Pleite]

btw is there any reason why one should not use the ac3 files extracted by smart ripper?
For me there is no reason. Smartripper has to go through the whole movie, why not demux in the same time?
Don't worry, this is just a different notation for 5.1 sound, indicating 3 front channels and 2 back(surround) channels. I'm not sure, but I think that it does mean that there is no extra bass channel.
Maybe dvd2avi doesn't quote the bass-channel as a audio-channel - in fact it's just naming. Why should dvd2avi remove the bass-channel? Wouldn't this be quite complicated?
I don't remember I ever had an
"vts_01 AC3 T01 3_6ch 448Kbps DELAY 8ms.ac3"

A_Pleite

PS: are there 5.0 ac3's with 448 KBit/s