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XM Codec

L

listner2

Guest
Has anyone been listening to XM on AOL? I know it's been there a while, but I finally listened to it for the first time tonight.

Since it's inception, I thought Aol Radio sounded pretty good as far as codec quality goes, but not CD quality. Obviously, everyone knows XM's codec sucks.

But XM on Aol sounds amazing! It's a little better than the Aol channels, and of course just about anything is better than the quality of the XM service itself. Although there is even less dynamics (loudness) processing than XM itself has, the quality is great.

Finally I can enjoy the great XM programming without having to bear the tin can sound of the actual XM service!

If you don't believe me, run both and do an A/B comparison.
 
> Has anyone been listening to XM on AOL? I know it's been
> there a while, but I finally listened to it for the first
> time tonight.
>
> Since it's inception, I thought Aol Radio sounded pretty
> good as far as codec quality goes, but not CD quality.
> Obviously, everyone knows XM's codec sucks.

XM's codec does not suck. They have what is possibly the most advanced audio codec out there. It's just very compressed because there's only so much data you can fit over a crappy 12.5 Mhz of the airwaves. It stinks, but that's what the FCC gave them. :/
 
> > Has anyone been listening to XM on AOL? I know it's been
> > there a while, but I finally listened to it for the first
> > time tonight.
> >
> > Since it's inception, I thought Aol Radio sounded pretty
> > good as far as codec quality goes, but not CD quality.
> > Obviously, everyone knows XM's codec sucks.
>
> XM's codec does not suck. They have what is possibly the
> most advanced audio codec out there. It's just very
> compressed because there's only so much data you can fit
> over a crappy 12.5 Mhz of the airwaves. It stinks, but
> that's what the FCC gave them. :/
>
I realize that they have limited bandwidth and that the codec sounds very good for that amount, but if they cut the number of channels and added some audio processing, it could be much better. When the codecs get better, then they could add more channels. Yet they continut to tout "digital qulaity" misleading everyone into thinking their quality is superior to broadcast. I would have never launched the service with that quality, especially charging for the service! A good strong FM signal sounds much better and is Free.

The tiny bit of audio processing the Neural Audio boxes do is a joke. For an obvious example, Try listening to the Open Road channel during a show that XM produces (Bill Mack show or Dale Sommers. The audio gets compressed at every peak especialy during the phone calls, and takes a long time to release. It's unlisenable unless you have the volume cranked. (Steve Sommers overnight must have there own processing - it sounds better) A format like this should have the attack and release times set so fast you don't hear it working. It's just typical of all of the channels. Most of the music channels don't even seem to have any AGC, if they do it's so slow it's ineffective.
 
>
> If you don't believe me, run both and do an A/B comparison.
>
Well, I tried the AOL version of XM through Winamp, and XM Online is still better. Don't know if you get better quality through AOHell itself, but through Winamp, you only get a 16kbps mpe, probably mpePRO. I'm listening to '60's on 6 as I type this, and even though it says stereo, none of the songs are in stereo. I also tried the '70's channel and it was the same way. I thought maybe I had it set up for modem quality, but I checked and it said Broadband The other thing I notice is the artifacts you get with a low quality mp3PRO. The XM Online feed, on the other hand, while not CD quality, does sound much better at 64kbps.

Try doing an A/B on those two sources. If you don't like the XM Online browser player, get Xtream XM. What I can't wait for is the DirectTV feeds. They should be superior to any currently available XM feed.
 
> > > Has anyone been listening to XM on AOL? I know it's been
>
> > > there a while, but I finally listened to it for the
> first
> > > time tonight.
> > >
> > > Since it's inception, I thought Aol Radio sounded pretty
>
> > > good as far as codec quality goes, but not CD quality.
> > > Obviously, everyone knows XM's codec sucks.
> >
> > XM's codec does not suck. They have what is possibly the
> > most advanced audio codec out there. It's just very
> > compressed because there's only so much data you can fit
> > over a crappy 12.5 Mhz of the airwaves. It stinks, but
> > that's what the FCC gave them. :/
> >
> I realize that they have limited bandwidth and that the
> codec sounds very good for that amount, but if they cut the
> number of channels and added some audio processing, it could
> be much better. When the codecs get better, then they could
> add more channels. Yet they continut to tout "digital
> qulaity" misleading everyone into thinking their quality is
> superior to broadcast. I would have never launched the
> service with that quality, especially charging for the
> service! A good strong FM signal sounds much better and is
> Free.
>
> The tiny bit of audio processing the Neural Audio boxes do
> is a joke. For an obvious example, Try listening to the Open
> Road channel during a show that XM produces (Bill Mack show
> or Dale Sommers. The audio gets compressed at every peak
> especialy during the phone calls, and takes a long time to
> release. It's unlisenable unless you have the volume
> cranked. (Steve Sommers overnight must have there own
> processing - it sounds better) A format like this should
> have the attack and release times set so fast you don't hear
> it working. It's just typical of all of the channels. Most
> of the music channels don't even seem to have any AGC, if
> they do it's so slow it's ineffective.
>

If you set the release times too fast it'll pump. You want fast attack, slow release with make-up gain. XM runs racks and racks of Omnia.net's to process all the channels. I suspect they'll be upgrading to the new Omnia HD multicast boxes at some point.

The problem is that with the aac+ Codecs and the sheer number of channels crammed into limited sat bandwidth, they are running noticeably low bitrates on some of the channels. The traffic channels sound like computers talking, that is how bad the artifacts are.

AOL used to use aacPlus as well for their AOL Radio service though their player. It sounded really good.
 
> XM runs racks
> and racks of Omnia.net's to process all the channels.
I wish they'd run some sort of processing to even out the sound levels on all of the songs on their channels. This has been a persistant problem with XM's audio. It's not that different channels have different sound levels, but when listening to one channel, certain songs will be much louder and fuller than others. It sounds like listening to a personal CD collection. XM needs to run some processing in the audio chain to even everything out. Most all FM's do this, and Sirius seems to do this as well. I like Sirius's processing more than XM's because it sounds more processed and more evened out, like traditional FM's do. XM's sound isn't that bad overall, but the varying levels can be irritating.
 
> > XM runs racks
> > and racks of Omnia.net's to process all the channels.
> I wish they'd run some sort of processing to even out the
> sound levels on all of the songs on their channels. This
> has been a persistant problem with XM's audio. It's not
> that different channels have different sound levels, but
> when listening to one channel, certain songs will be much
> louder and fuller than others. It sounds like listening to
> a personal CD collection. XM needs to run some processing
> in the audio chain to even everything out. Most all FM's do
> this, and Sirius seems to do this as well. I like Sirius's
> processing more than XM's because it sounds more processed
> and more evened out, like traditional FM's do. XM's sound
> isn't that bad overall, but the varying levels can be
> irritating.
>
i totally agree..listen to 41 than go to 22..the levels will bust your speakers if it is turned way up on 41 before switching..also on 41 if they go from a song from 1982 to a new song the same thing happens..its really annoying.<P ID="signature">______________
note to tvland...bring back wkrp!!!</P>
 
I'd be using Ariannes for processing if I were XM.



> > > > Has anyone been listening to XM on AOL? I know it's
> been
> >
> > > > there a while, but I finally listened to it for the
> > first
> > > > time tonight.
> > > >
> > > > Since it's inception, I thought Aol Radio sounded
> pretty
> >
> > > > good as far as codec quality goes, but not CD quality.
>
> > > > Obviously, everyone knows XM's codec sucks.
> > >
> > > XM's codec does not suck. They have what is possibly the
>
> > > most advanced audio codec out there. It's just very
> > > compressed because there's only so much data you can fit
>
> > > over a crappy 12.5 Mhz of the airwaves. It stinks, but
> > > that's what the FCC gave them. :/
> > >
> > I realize that they have limited bandwidth and that the
> > codec sounds very good for that amount, but if they cut
> the
> > number of channels and added some audio processing, it
> could
> > be much better. When the codecs get better, then they
> could
> > add more channels. Yet they continut to tout "digital
> > qulaity" misleading everyone into thinking their quality
> is
> > superior to broadcast. I would have never launched the
> > service with that quality, especially charging for the
> > service! A good strong FM signal sounds much better and is
>
> > Free.
> >
> > The tiny bit of audio processing the Neural Audio boxes do
>
> > is a joke. For an obvious example, Try listening to the
> Open
> > Road channel during a show that XM produces (Bill Mack
> show
> > or Dale Sommers. The audio gets compressed at every peak
> > especialy during the phone calls, and takes a long time to
>
> > release. It's unlisenable unless you have the volume
> > cranked. (Steve Sommers overnight must have there own
> > processing - it sounds better) A format like this should
> > have the attack and release times set so fast you don't
> hear
> > it working. It's just typical of all of the channels. Most
>
> > of the music channels don't even seem to have any AGC, if
> > they do it's so slow it's ineffective.
> >
>
> If you set the release times too fast it'll pump. You want
> fast attack, slow release with make-up gain. XM runs racks
> and racks of Omnia.net's to process all the channels. I
> suspect they'll be upgrading to the new Omnia HD multicast
> boxes at some point.
>
> The problem is that with the aac+ Codecs and the sheer
> number of channels crammed into limited sat bandwidth, they
> are running noticeably low bitrates on some of the channels.
> The traffic channels sound like computers talking, that is
> how bad the artifacts are.
>
> AOL used to use aacPlus as well for their AOL Radio service
> though their player. It sounded really good.
>
 
> > > XM runs racks
> > > and racks of Omnia.net's to process all the channels.
> > I wish they'd run some sort of processing to even out
> the
> > sound levels on all of the songs on their channels. This
> > has been a persistant problem with XM's audio. It's not
> > that different channels have different sound levels, but
> > when listening to one channel, certain songs will be much
> > louder and fuller than others. It sounds like listening
> to
> > a personal CD collection. XM needs to run some
> processing
> > in the audio chain to even everything out. Most all FM's
> do
> > this, and Sirius seems to do this as well. I like
> Sirius's
> > processing more than XM's because it sounds more processed
>
> > and more evened out, like traditional FM's do. XM's
> sound
> > isn't that bad overall, but the varying levels can be
> > irritating.
> >
> i totally agree..listen to 41 than go to 22..the levels will
> bust your speakers if it is turned way up on 41 before
> switching..also on 41 if they go from a song from 1982 to a
> new song the same thing happens..its really annoying.
>
If the processing is set right it won't "pump". Ever use a Orban 8200 or 8400? You can get a hell of a lot of compression without a pumping sound. Can't the omnia.net do mutiband limiting (or multiband compression in Omnia's case)? It can't degrade the audio much more than it already is. I never knew they were running omnia's. I assumed that the Neural Audio boxes did what little processing seems to be there.

As I stated in my original post, if you listen to open road on a show produced by xm, you will notice pumping because the release times are set too slow. If you set them fast enough, you won't hear it work. You may loose a little punch, but the trade off would be well worth it.

Yes, I knew that AOL Radio was using AAC. They obviously have a direct feed from XM's studios. Interesting though that XM's own streaming seems to be streamed from XM radios. The quality is ok, but no better than an actual XM radio and not nearly as nice as the AOL feeds.
 
> I'd be using Ariannes for processing if I were XM.

Maybe in front of the Omnias. The .Net's are designed to deal with the problems of psycho-acoustic masking the aacPlus codecs create. Omnia now has an even better box out.

Given that on a compressed stream you really only need levelling, Arianne's may be all that would be needed if they didn't have the desire to re-EQ and customize each stream.

> > > > > Has anyone been listening to XM on AOL? I know it's
> > been
> > >
> > > > > there a while, but I finally listened to it for the
> > > first
> > > > > time tonight.
> > > > >
> > > > > Since it's inception, I thought Aol Radio sounded
> > pretty
> > >
> > > > > good as far as codec quality goes, but not CD
> quality.
> >
> > > > > Obviously, everyone knows XM's codec sucks.
> > > >
> > > > XM's codec does not suck. They have what is possibly
> the
> >
> > > > most advanced audio codec out there. It's just very
> > > > compressed because there's only so much data you can
> fit
> >
> > > > over a crappy 12.5 Mhz of the airwaves. It stinks, but
>
> > > > that's what the FCC gave them. :/
> > > >
> > > I realize that they have limited bandwidth and that the
> > > codec sounds very good for that amount, but if they cut
> > the
> > > number of channels and added some audio processing, it
> > could
> > > be much better. When the codecs get better, then they
> > could
> > > add more channels. Yet they continut to tout "digital
> > > qulaity" misleading everyone into thinking their quality
>
> > is
> > > superior to broadcast. I would have never launched the
> > > service with that quality, especially charging for the
> > > service! A good strong FM signal sounds much better and
> is
> >
> > > Free.
> > >
> > > The tiny bit of audio processing the Neural Audio boxes
> do
> >
> > > is a joke. For an obvious example, Try listening to the
> > Open
> > > Road channel during a show that XM produces (Bill Mack
> > show
> > > or Dale Sommers. The audio gets compressed at every peak
>
> > > especialy during the phone calls, and takes a long time
> to
> >
> > > release. It's unlisenable unless you have the volume
> > > cranked. (Steve Sommers overnight must have there own
> > > processing - it sounds better) A format like this should
>
> > > have the attack and release times set so fast you don't
> > hear
> > > it working. It's just typical of all of the channels.
> Most
> >
> > > of the music channels don't even seem to have any AGC,
> if
> > > they do it's so slow it's ineffective.
> > >
> >
> > If you set the release times too fast it'll pump. You want
>
> > fast attack, slow release with make-up gain. XM runs racks
>
> > and racks of Omnia.net's to process all the channels. I
> > suspect they'll be upgrading to the new Omnia HD multicast
>
> > boxes at some point.
> >
> > The problem is that with the aac+ Codecs and the sheer
> > number of channels crammed into limited sat bandwidth,
> they
> > are running noticeably low bitrates on some of the
> channels.
> > The traffic channels sound like computers talking, that is
>
> > how bad the artifacts are.
> >
> > AOL used to use aacPlus as well for their AOL Radio
> service
> > though their player. It sounded really good.
> >
>
 
> > > > XM runs racks
> > > > and racks of Omnia.net's to process all the channels.
>
> > > I wish they'd run some sort of processing to even out
>
> > the
> > > sound levels on all of the songs on their channels.
> This
> > > has been a persistant problem with XM's audio. It's not
>
> > > that different channels have different sound levels, but
>
> > > when listening to one channel, certain songs will be
> much
> > > louder and fuller than others. It sounds like listening
>
> > to
> > > a personal CD collection. XM needs to run some
> > processing
> > > in the audio chain to even everything out. Most all
> FM's
> > do
> > > this, and Sirius seems to do this as well. I like
> > Sirius's
> > > processing more than XM's because it sounds more
> processed
> >
> > > and more evened out, like traditional FM's do. XM's
> > sound
> > > isn't that bad overall, but the varying levels can be
> > > irritating.
> > >
> > i totally agree..listen to 41 than go to 22..the levels
> will
> > bust your speakers if it is turned way up on 41 before
> > switching..also on 41 if they go from a song from 1982 to
> a
> > new song the same thing happens..its really annoying.
> >
> If the processing is set right it won't "pump". Ever use a
> Orban 8200 or 8400? You can get a hell of a lot of
> compression without a pumping sound. Can't the omnia.net do
> mutiband limiting (or multiband compression in Omnia's
> case)? It can't degrade the audio much more than it already
> is. I never knew they were running omnia's. I assumed that
> the Neural Audio boxes did what little processing seems to
> be there.
>
> As I stated in my original post, if you listen to open road
> on a show produced by xm, you will notice pumping because
> the release times are set too slow. If you set them fast
> enough, you won't hear it work. You may loose a little
> punch, but the trade off would be well worth it.
>
> Yes, I knew that AOL Radio was using AAC. They obviously
> have a direct feed from XM's studios. Interesting though
> that XM's own streaming seems to be streamed from XM radios.
> The quality is ok, but no better than an actual XM radio and
> not nearly as nice as the AOL feeds.
>

Actually, IMHO "pumping" is most noticable with quick attack/release times - hence the up/down up/down "pump" as if a compression gate were being hit. If have fairly quick attacks to grab the peaks, and a slow release with generous make-up gain, you won't have any noticeable pumping and there won't be the brief LOUD and then long soft passages.

Our stream is just using a simple compressor set with quick attacks, slow release, and make up gain and it works fine for us at 32kHz and 96kps mp3 rates. If I were really iritated with the mp3 artifacts, I would use the new Omnia with multiband look-ahead limiting. But I am not $6k bothered by it.
 
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