What kind of AC3 is it?

[jriker1]

I have an AVI file that has AC3-2.1 in the filename. With GSpot it's telling me it's AC-3 Stereo. Is it really 2.0 or is GSpot not reporting the audio correctly? If not, how do you tell for sure? Thanks.

JR

[unskinnyboy]

No such thing as 2.1. Load the avi into VirtualDubMoD and check File -> File Information. Under Audio Stream, check the number of channels.

[jriker1]

Thanks!! I didn't think there was either, however Sonic Soft Encoder seems to feel it's an option when encoding. It has an option "2/1 (L,R,l)" for Audio coding mode.

[tebasuna51]

Don't mistake the "/" with the point "."
X.1 -> LFE present
X.0 -> LFE not present

From Sonic Foundry Help:

Dolby Digital channel designations

1/0 Center
2/0 Left, Right
3/0 Left, Center, Right
2/1 Left, Right, Surround
3/1 Left, Center, Right, Surround
2/2 Left, Right, Left Surround, Right Surround
3/2 Left, Center, Right, Left Surround, Right Surround

LFE enable

This option enables or disables the encoding of the LFE or Low Frequency Effects channel. This channel is typically used as a sub-woofer channel.
The LFE channel is only available with 3/0 mode and higher, therefore this option will not be available in the two-channel version of Soft Encode.

[jriker1]

Ahh. Interesting. So when do you use the x/1 "Surround" setting as opposed to x/0 setting?

[j_olson]

Well, 2/0 is plain stereo... 2/1 has, as shown above, an added mono surround channel - very rarely used.