One of the most talked about topics for discussion in this forum is the setting at which compressed audio approaches transparency in sound to the original to 98% of listeners. There are thousands of post son this for MP3, OGG, and MPC in this forum - including sticky guides.

However, I cannot find a definitive answer for the 2 codecs likliest to secede MP3 - AAC and WMA. (And if you disagree about my statements on what will secede MP3, save it for another thread. That is not the topic of this thread).

Does anyone know at what bitrate "LAME APS" quality is achieved for AAC and WMA? I have heard AAC reported at a 30% improvement. The majority of my tunes clock in at around 220 with LAME APS, which would suggest AAC can offer the same quality at around 175. That is awesome if true!!!!

What about WMA? Where does it achieve transparency at? No one even discusses it in this forum. I have listened to it at VBR 98 and VBR 90 and it sounds great to me, but I respect others with better ears opnions. VBR 98 produces MASSIVE file sizes with bit rates at 300+, while VBR 90 equates approximately to LAME APS in size.

I'm very curious. I think one of these 2 codecs is the future (perhaps both) and I am interested in where they hit that magical transparency sound for almost all listeners.

From what I have read (not tested myself) WMA never reaches transparency.

I think it depends mostly on the sample being tested and your hearing.

I agree. And with my ears and Pearl Jam's "Once" WMA 90 and 98 sound transparent. But I do not trust my ears to the level of some in here.

never say never

Since you're targeting LAME APS, quality I suggest using AAC at 192kbps (which is the average bitrate of LAME APS) just to be safe. Anything above that will be a waste of bits.

AAC 192 VBR I assume? Also, I do not know what type of music you listen to, but rare is the file that is 192 at APS on my PC. 200-240 is the average for LAME APS.

What about WMA? Someone already said it never is transparent, but I find that hard to believe. Despite the ridiculous file size, WMA VBR 98 sounds great. I find it hard to believe it is not transparent. The question is, must one go that high with WMA for transparancy.

Well, using AAC in CBR mode is a waste of bits per se.

To get results similar to APS, I would recommend the -normal VBR preset. It should give you bitrates around 170kbps.

Transparency is relative. When you say "transparent", there are two major variables (that I can think of anyway). The listener and the music.

Everyone has a different level of hearing ability, each with a different audible frequency band and different sensitivities within their audible band.

Every song is different as well. There's a lot to consider, but generally the more complex the music, the harder to encode, and hence the farther away transparency will be. Also, you have to consider the low-pass setting, and many other factors of encoder configuration as well.

I have what I'd consider average hearing. LeAnn Rimes How Do I Live would likely be transparent to me at 128kbps, but I was able to ABX Fatboy Slim's Kalifornia in high-bitrate VBR from the original WAV.

What are your musical tastes? And how good is your hearing? You can use a tone generator (like NCH or Timo Esser's) to help determine your audible frequency range so you'll know where lowpass should be set to not impede transparency for you. The bottom line is that tranparency, as I understand it, is completely subjective. What's tranparent to me may or may not be transparent to another person, or vice-versa.

As for the "minimum bitrate" for transparent WMA, I was not able to find one for myself with some pretty tough music (mostly hard techno). I tested up to the highest VBR setting for lossy WMA encoding using the dBpowerAMP WMA plug-in and Windows Media Player 9. Of course, lossless WMA would be transparent to anyone. If your music is even tougher on a WMA encoder *and* you have exceptional hearing, then you'll likely not find a transparent lossy WMA setting. If your music is relatively easy to encode and you have average (or lower) hearing abilities, then maybe 192 would be fine, or perhaps a midrate-VBR.

I know I ramble, but I hope this helps...

Why bother with all this? Just let a quality-based VBR method do it for you. Tone generators won't tell you how you can hear high frequencies in music, just by themselves. I have trouble telling the difference between a lowpassed file at 16kHz and the original, even though I can hear a test tone all the way to 21kHz.

Basically, just choose a quality-based VBR encoder (not ABR), choose a quality level that sound good to you on a few tracks, then let the encoder decide how to do things. Don't mess with it depending on the music type, etc.

That's a good point. My intended focus was just to point out that "transparency" is relative, and that (IMHO) no absolute line exists between "live and Memorex" when it comes to lossy encoding. One persons "Memorex" is another persons "live". One person finding transparency on 99% of their music at 128kbps cbr doesn't change the fact that the next person might be able to audibly seperate *any* lossy encoding from lossless, and hence only be truly happy with FLAC (or the like).

It's also a matter of how neurotic someone is, as well. I personally didn't want to only try a few songs and then trust the encoder to use quality-based VBR to deal with the rest. I did a lot more ABXing than I originally planned on, doing everything I could to break even high-VBR settings. Then, as anyone with my neurosis would do, I settled on the lowest setting that I couldn't break with *anything* I tried.

But, assuming most people in the world don't have my curse , a "baseline" could be determined if enough people were tested in order to find what was transparent for a given percentage of them...95%?...99%? I agree that quality-based VBR would do the job in the vast majority of cases. For WMA, maybe that's VBR -quality 90 or so?

Unless your a picky techno-freak like I am who won't accept what will work most of the time, but only what works all of the time...