ITunes Store surround sound?

[lawman]

I recently set up a surround sound system at home, and I've noticed something. Typically, when I'm playing former MP3s through iTunes on my MBP (connected to my AV Receiver through a digital optical cable) it plays only in stereo. However my iTunes downloads play in full surround sound. How come? I was under the impression that while AACs are capable of surround sound typically iTunes downloads are in stereo. Am I wrong? Also, is there any way I can get my former MP3s now converted to iTunes format to play in surround?

 

[walnuts]

Are you sure that it is really surround sound? I think some stereos convert stereo signal into pseudo surround (it puts stuff that goes through both channels to the center speaker, picks some sounds to go to the rear speakers, etc., but the recording has no specific instructions as to which speakers the sounds go to other than left or right)

 

[danny_w]

It could be that the downloads you are talking about are encoded in Dolby ProLogic, which encodes surround sound onto a stereo signal. While not the same as Dolby Digital, it is the forerunner of the same, and has been around since the 70's at least; this is the way that analog tv shows that are in surround audio are encoded. However I was unaware that iTunes downloads were so encoded.

 

[walnuts]

You know, its interesting- I can't seem to find anywhere on the iTunes help that descibes all this. You'd think that they'd have to describe exactly what you are purchasing.

 

[lawman]

I was wondering the same thing. I currently have my receiver set on Dolby Prologic / II. I'm pretty sure it's something to do with the recording and not my receiver since I don't get the same level of surround sound with my legacy MP3s. Also, I notice that the sound is coming through 5.1 channels, not 4.1 (my understanding is that Prologic / PLII only powers 4.1 channels).

Its quite confusing.

 

[walnuts]

I was wondering the same thing. I currently have my receiver set on Dolby Prologic / II. I'm pretty sure it's something to do with the recording and not my receiver since I don't get the same level of surround sound with my legacy MP3s. Also, I notice that the sound is coming through 5.1 channels, not 4.1 (my understanding is that Prologic / PLII only powers 4.1 channels).

Its quite confusing.

I thought Pro Logic had 5.1 (2 front speakers, a center speaker, and two rear speakers and the .1 was the subwoofer)? I guess I've been out of the loop with this stuff.