Difference between 6 channel and 2/6 Channel

[Clnthl]

Hi there,
sorry if this is a bit of a noob question I use media info on my mac before putting things over to my hard drive just to make sure everything will be compatible with my tv/media player. But I have some videos which say for example:
Audio: English, 384 Kbps, 48.0 LHx, 6 Channels, AC-3
I then have some others which say for example:
Audio: English, 320 Kbps, 48.0 KHz, 6 channels / 2 channels, AAC (LC)

Now I know that 2 channel isn't surround sound but what does this 6/2 mean?
Thanks in advance!

[Detmek]

Usually it means that audio is encoded as 6-channel using Nero AAC encoder.

[johns0]

It means the video file contains 5.1 ac3 or acc as well as 2.0 aac audio.

[hello_hello]

Which container are you using? MP4, MKV etc

It's probably due to a change in standards. Originally the only possibilities were 2ch or 1ch for MP4, and some encoders still write either 2ch or 1ch for backward compatibility, even when the audio is multi-channel. MediaInfo displays the mp4a.channelcount, which is written as 2ch, but it obviously has a way of determining the real channel count. When they're different, it displays both.

In Basic view mode MediaInfo displays this:
Audio: English, 320 Kbps, 48.0 KHz, 6 channels / 2 channels, AAC (LC)

But in Text or HTML view it'll display this:
Channel(s) : 2 channels
Channel(s)_Original : 6 channels
Channel positions : Front: L C R, Side: L R, LFE

I know nothing about MAC software but of the four AAC encoders I have on my PC, only one still writes the incorrect channel count info, and that's fhgaacenc.exe. I don't think fdkaac.exe ever did, QAAC doesn't, although it did originally, and I don't recall if neroAacEnc.exe ever did. Some more info.

MyMP4BoxGUI writes mp4a.channelcount as either 2ch or 1ch when muxing, even if the audio stream being muxed didn't. I don't know what other MP4 muxers might do.

[El Heggunte]

...................

I know nothing about MAC software but of the four AAC encoders I have on my PC, only one still writes the incorrect channel count info, and that's ffdcaenc.exe.

[Ex Machinas]

I just watched a file that said stereo 2 channels. However when setting receiver to Dolby Surround, it seemed to sound perfect for all appropriate sounds out of all speakers. Would a movie encoded with 5.1 have sounded better or the same as the upconversion ( I assume)?

[hello_hello]

...................

I know nothing about MAC software but of the four AAC encoders I have on my PC, only one still writes the incorrect channel count info, and that's ffdcaenc.exe.

I'll bite.......
What imaginary issue do you have with what I wrote?

Oh I see.... I wrote the wrong encoder name in my post, but instead of pointing out ffdcaenc.exe isn't an AAC encoder, you quoted my post while highlighting a few words because somehow that conveys what you were trying to say far more clearly. I wrote the post and it took me a minute to work out what you on about. The other two or three people who read your post and who've heard of ffdcaenc.exe might also work it out, but for the benefit of the remaining 99.999999999999% of readers of this thread......

ffdcaenc.exe isn't an AAC encoder. I copied the file names of the encoders from Windows Explorer and pasted them here, and in one instance I must have copied and pasted the wrong encoder name. I should have written:

I know nothing about MAC software but of the four AAC encoders I have on my PC, only one still writes the incorrect channel count info, and that's fhgaacenc.exe. I don't think fdkaac.exe ever did, QAAC doesn't, although it did originally, and I don't recall if neroAacEnc.exe ever did.

I've also corrected my original post.

[hello_hello]

I just watched a file that said stereo 2 channels. However when setting receiver to Dolby Surround, it seemed to sound perfect for all appropriate sounds out of all speakers. Would a movie encoded with 5.1 have sounded better or the same as the upconversion ( I assume)?

5.1ch should sound better.
Could the 2 channel audio have been encoded with Dolby ProLogic and could your receiver be decoding it, or would it just be upconverting? I think Dolby Prologic and Dolby Surround are sometimes used interchangeably, even by Dolby, and to confuse the issue more they now use Dolby Surround to describe upmixing too.
Either way, discreet 5.1ch should sound better, if you're into that sort of thing. I've never liked surround sound myself.