Sirius Audio Format?

[otk]

does anyone know which audio format sirius uses and the bit rate?

i know they use more compression on the talk channels than on the music channels

i would love to know the specs of each

[xzitony]

SIRIUS chose early on to use a customized version of PAC, calling it version 4.

This is the same codec that HD Radio abandonded early on.

Since it's older, it doesn't allow them to lower to bitrates as much as XM and HD Radio, and in the case of XM vs. SIRIUS is why they only have 130 channels compared to XM's 170.

[otk]

do you know what the bit rate is?

is it close to mp3's 128 kBit/s, 44.100 Hz, Stereo ?


i know they use more compression on the talk channels because my starmate can hold 48 minutes of music or howard stern in it's buffer but the other talk channels like the comedy, martha, left/right, my starmate can buffer 90 minutes of those channels

[xzitony]

it's definitely lower... I can't speak for SIRIUS because they use a system where the bitrate constantly changes. On XM, music channels range from 24kbps to 64kbps--their CODEC is aacPlus which "claims" a 64kbps aacPlus is equivalent to more of a 192kbps MP3 but only 2 XM channels use it. Most of them are much lower than that, and I'd guess SIRIUS is similar.

[otk]

ok, i'm just trying to figure out what would be a perfect match to record off my sirius receiver to my computer sound card

[ClubSteeler]

XM has taken what used to be an advantage, and now compressed down so far that Sirius actually has the better audio quality these days.

I've read on a forum, but can not confirm, that most Sirius channels are somewhere around 45kbps.

No idea how true the above statement is...

[otk]

Originally Posted by ClubSteeler

XM has taken what used to be an advantage, and now compressed down so far that Sirius actually has the better audio quality these days.

I've read on a forum, but can not confirm, that most Sirius channels are somewhere around 45kbps.

No idea how true the above statement is...

that seems too low to me, the music channels sound as good as any 128bit mp3 that i've heard

45 sounds about right on the talk channels (except for stern, stern's channels get the same bit rate as the music channels) but on the other talk channels, you can hear the "swooshing" of the digital compression, i would bet it's as low as 32 bit mono on some of them

[xzitony]

Originally Posted by ClubSteeler

XM has taken what used to be an advantage, and now compressed down so far that Sirius actually has the better audio quality these days.

I've read on a forum, but can not confirm, that most Sirius channels are somewhere around 45kbps.

No idea how true the above statement is...

I think the 45kbps is right because the PAC CODEC can't go much lower than that before starting to really break down so I think you're right about all those statements.

Where XM can get away with 24kbps channels (like Squizz), PAC could never go that low. Now a 24kbps on XM doesn't sound great but they obviously decided to make that trade off.

[otk]

here are some short samples recorded off my sirius radio

sirius channel 9 (the pulse, 90s music)

http://rapidshare.com/files/40352294...nel_9.mp3.html

sirius channel 80 (symphony hall)

http://rapidshare.com/files/40352344...el_80.mp3.html