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An anonymous reader writes "Slate has an article about Internet radio stations that use the aacPlus codec from XM satellite radio instead of MP3. Some of the ones they link to sound pretty good even at 24 kbps."
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I've reencoded files in OGG, WMA at 64kbs, and it's fairly equivalent
You're reencoding from XM and trying to compare quality? The XM codec has already thrown away lots of information, transcoding to another format is only going to throw away more, it's certainly not going to magically get the information back somehow.
It's like chopping an apple in half, and trying to determine whether you can chop one of the halves in a way that gets you more than half an apple. Impossible by definition.
SomaFM, an entirely listener-supported Internet radio site, has a few streams in aacPlus. I recommend them, they play stuff that you normally don't run across.
aacPlus is just a marketing name for the HE-AAC standard.
There are GPL'ed implementations of HE-AAC decoders, for example at http://www.audiocoding.com, so these streams should be playable on open source systems, too.
Btw. Some of technical details in the article (notably about parametric stereo) are *complete bollocks*. What they describe is Mide-Side stereo.
Parametric stereo transmits only a mono channel plus a very small amount of sideband information that describes how to reconstruct the stereo image (via decorrelation and fading).
Satellite radio is a broadcast medium, which means one signal is sent down to a large area, and anyone in that area can receive the same signal without quality loss as the number of listeners goes up.
It can be compared to any other radio broadcast; just because you're listening to 99.9 RIAA-0wn5-j00 FM doesn't mean other people have a weaker signal or diminished sound quality.
-Z
just because you're listening to 99.9 RIAA-0wn5-j00 FM doesn't mean other people have a weaker signal or diminished sound quality.
they wont have a diminished sound quality (for the most part, if its all on the edge of the range they might). but they most definately will always have a weaker signal in the immediate area. this is because your antenna itself distorts the field around it when it attracts the singal, and a small amount of energy is used in the reproduction of the sound wave when the receiver is receiving the signal. now typically this is such a low drop that you wont notice it but it is there.
Yes, such a low drop as to even not be worth discussing.
Yes, HE AAC and AAC+ are the same thing. HE AAC is the name that MPEG gives it, and AAC+ is Coding Technologies name for their implementation.
Next up is AAC PS, for parametric stereo, which applies the SBR techniques to synthesizing stereo. Gives another big leap yet for music listening - 24 Kbps is good enough for people who can live with MP3 @ 160 or so.
My video compression blog
I think you're missing the point. HE AAC is more than twice as efficient as today's leading class of codecs (AAC, WMA, Ogg). Twice is a big deal! Think of the difference between, say, MPEG-2 and H.264 or WMV9 Advanced Profile. It took video codecs a full DECADE to get the kind of improvement jump we're getting with HE AAC. That 20 Kbps stream can be a great sounding 44.1 with HE AAC - better than that 64 Kbps VBR stream you cite.
The technology has been around for a while in enterprise systems, but is only now trickling down to desktop use.
And AAC PS (parametric stereo) is just around the corner, which is more efficient yet.
My video compression blog
Some people wind up saving mono files that duplicate the audio on both right and left channels, rather than save it with a single mono channel.
You wind up with a file that's twice as big, with no benefit.
Here's what I do: Bitty Browser & Andromeda