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XM codecs
- Thread starter mgpt6
- Start date
XM uses aacPlus v1, aka HE-AAC, to broadcast audio, except for traffic and weather, which uses AMBE.
The bitrate varies for music. The majority of them are 32 kbps. A few that require more fidelity are 40 or 48, and the classical channels are up to 56 kbps. There used to be a channel called Fine Tuning that was 72 kbps. Then there are music channels that are 24 kbps, and mono, including 40s on 4, Sur la Route, and Radio Disney (which is not considered a music channel anyway). The AMBE channels are all 4 kbps.
Most talk is 16 kbps and mono. This includes all sports play-by-play. A lucky few talk channels are 24 kbps, and some like XMPR go back and forth depending on the time of day. Channels 100, 101, and 202 are all 32 kbps and stereo.
The XM audio codec is much more efficient than what Sirius uses, which is ePAC, so Sirius runs at higher bitrates. They also have significantly fewer channels. Which service sounds better to the ear is subjective.
The bitrate varies for music. The majority of them are 32 kbps. A few that require more fidelity are 40 or 48, and the classical channels are up to 56 kbps. There used to be a channel called Fine Tuning that was 72 kbps. Then there are music channels that are 24 kbps, and mono, including 40s on 4, Sur la Route, and Radio Disney (which is not considered a music channel anyway). The AMBE channels are all 4 kbps.
Most talk is 16 kbps and mono. This includes all sports play-by-play. A lucky few talk channels are 24 kbps, and some like XMPR go back and forth depending on the time of day. Channels 100, 101, and 202 are all 32 kbps and stereo.
The XM audio codec is much more efficient than what Sirius uses, which is ePAC, so Sirius runs at higher bitrates. They also have significantly fewer channels. Which service sounds better to the ear is subjective.
All I can say is the distortion I hear on the high frequencies drives me crazy!
When I first bought XM, many years ago, they had fewer channels, but the 48KHz bitrate for the music channels was very, very good, and sounded much better than HD-FM radio. The audio processing was even light too!
It's a shame that XM can't upgrade to aacPlus v2, because it's not compatible with the hardware. With the integration of parametric stereo, it would improve the stereophonic XM channels by 40%.
virus, it's my understanding that the "aacPlus v2" is semi-backwards compatible! Only the really old 1st generation XM hardware (most that doesn't work anymore) will resort to MONO, but everything made since about 2004 will accept the upgrade. How can we suggest this to a techie at XM, provided that they all haven't been fired, and somebody there actually gives a s*$t?
XM computers should be able to tell what hardware you have based on your serial number, and/or by the FCC ID number on the radio.
Just like XM did with giving us FM modulators for those with the high-powered modulators (based on FCC ID#), XM/Siri could give away NEW low-end radios to those old timer subs with that were aacPlus v1 compatible so that they can hear HQ stereo aacPlus v2 o their new radio. It would be totally voluntary. They could opt to keep their old hardware running, but just be stuck with HQ mono, or take up the offer on a new rig with aacPlus v2.
How could we present this to XM?
XM computers should be able to tell what hardware you have based on your serial number, and/or by the FCC ID number on the radio.
Just like XM did with giving us FM modulators for those with the high-powered modulators (based on FCC ID#), XM/Siri could give away NEW low-end radios to those old timer subs with that were aacPlus v1 compatible so that they can hear HQ stereo aacPlus v2 o their new radio. It would be totally voluntary. They could opt to keep their old hardware running, but just be stuck with HQ mono, or take up the offer on a new rig with aacPlus v2.
How could we present this to XM?
M
Mid West Clubber
Guest
I have Sirius and I think it sounds more realistic that XM.. XM sounds like a 20k AAC version1 stream, while sirius sounds about like a 96k wma stream.
Yea, to think I complained when XM went from their 48Kbs rate down to 42K and 40Kbs rates; then they dropped the rate way down to 32Kbs. It's barely better than HD radio! I wish they would consider the new codec for parametric stereo.
I also thought it would be sweet if XM went to ALL MUSIC only - then 100% of the bandwidth would be nice 48Kbs music channels and all the talk/sports/comedy would be on Sirius only. Then you'd have a choice and better audio quality for both. This would also mean that they would have to make more radios like the "Merge" - like Mel promised - the interchangeable satrad that works on both systems!
I also thought it would be sweet if XM went to ALL MUSIC only - then 100% of the bandwidth would be nice 48Kbs music channels and all the talk/sports/comedy would be on Sirius only. Then you'd have a choice and better audio quality for both. This would also mean that they would have to make more radios like the "Merge" - like Mel promised - the interchangeable satrad that works on both systems!
I'm another ex-sub that quit in part because of the declining sound quality. I wasn't happy with it when I signed up many years ago, but I was mainly interested in talk programming. But over time the sound quality kept improving and improving until one day I thought, "Wow, this is acceptable now!" and I was hooked. Then MLB debuted and the quality went to crap. It took another big dive with the merger and between the Sirius FM-like programming and the poor SQ, I ditched it.
And now that I have an HD radio, I can honestly say that HD DOES sound better to my ears than any of the XM streams, at least after baseball debuted.
My market(s) have several HD stations with no subchannels, and sound pretty decent despite the cascading codecs problem. Of course the music they play is just as bad as the crap Sirius threw on XM, but at least it's free crap.
And now that I have an HD radio, I can honestly say that HD DOES sound better to my ears than any of the XM streams, at least after baseball debuted.
My market(s) have several HD stations with no subchannels, and sound pretty decent despite the cascading codecs problem. Of course the music they play is just as bad as the crap Sirius threw on XM, but at least it's free crap.
M
Mid West Clubber
Guest
I ionly have siruis because I live in a remote Area without many clear stations,, Im not an audiophile by any means,, but even I can say they especially there Dance Hits channel BPM really needs better SQ.. Last night I bought a Wifi Radio which brings net radio much more easily available than a computer, but I still have to listen to XM in my car.
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