Is Codec ACC or PAC?

[mkjellman]

I was under the impression that Sirius used PAC but after reading this article it looks like they use ACC.

"http://www.stereophile.com/news/11323/"

"The lynchpin of those technologies, he explained, is CT-aacPlus, a third-generation audio encoding technology developed by Coding Technologies. CT-aacPlus combines Advanced Audio Coding (AAC), a standardized compression technology (the one used by Sirius Satellite Radio), with Coding Technologies' proprietary Spectral Band Replication (SBR™) technology, which creates additional bit-rate efficiency. XM claims the improvement makes its codec "30% more efficient than AAC alone.""

Which codec does Sirius use? Thanks

[RadioSam]

Sirius uses their own "special blend" of PAC. I believe they are calling it "version 4". Originally PAC was the codec to be used by Ibiquity for digital radio (HDRadio), but was abandoned. Sirius hired 8 PAC experts from Ibiquity at that time and have been tweaking on it ever since.

More info on Sirius here:
http://www.elecdesign.com/Articles/Print.cfm?ArticleID=5603

More about PAC before Ibiquity ditched it:
http://www.rwonline.com/reference-room/iboc/02_rw_hd_nrsc_3.shtml

That article is just wrong on that quote...

[AZCoyote]

Sirius uses their own "special blend" of PAC. I believe they are calling it "version 4". Originally PAC was the codec to be used by Ibiquity for digital radio (HDRadio), but was abandoned. Sirius hired 8 PAC experts from Ibiquity at that time and have been tweaking on it ever since.

More info on Sirius here:
http://www.elecdesign.com/Articles/Print.cfm?ArticleID=5603

More about PAC before Ibiquity ditched it:
http://www.rwonline.com/reference-room/iboc/02_rw_hd_nrsc_3.shtml

That article is just wrong on that quote...

This last article answers the question on why Sirius' talk/sports channels sound inferior to those of XM's. I guess PAC wasn't meant for that application.

On the other hand, the Sirius PAC team must have made some improvements with the higher bandwidth version, because (in my opinion), Sirius' music channels sounds much better than XM's music offerings in AACplus with Neural processing.

[RadioSam]

Somewhere I've seen an article that reflects PAC being superior to AAC at higher (96+) bitrates. Unfortunately - we don't see many channels getting that kind of attention.

This explains why some channels sound so incredibly good, and why others seem inferior to XM. S-Plex only complicates the comparisons - but is a necessary evil with such limited space to work with.

[SatListener101]

The short answer: Sirius uses PAC, XM uses AAC.

Sirius has made some remarkable sound quality enhancements since they first aired. It's now neck-and-neck with XM's.