Quick xbox question

DjB · Post by **DjB** » Thu Sep 16, 2004 9:02 pm

Hey, long time no speak..

Does anyone here know what bitrate the xbox encodes its mp3's at(if they're mp3's at all) when it copy's music from a cd? I tried the official xbox forums but even with 216,899 users, I havent heard an answer yet. I sure someone here would know.

Many thanks

MKE · Post by **MKE** » Thu Sep 16, 2004 9:07 pm

i think it's 96kb/s wma's...it might be 128 but i think standard wma cd quality bitrate is 96 so i would place my bet on that...

but it is wma format, not mp3

DjB · Post by **DjB** » Thu Sep 16, 2004 9:10 pm

Wow, that was quick. I always knew I could trust this place

The reason I was asking was because they do sound pritty crummy and my friend (with the xbox) cant notice it. So what Im gonna do is encode a song one at whatever the xbox has it at and one at 128kbps. Allthough that isnt the highest thats where I notice that kind of metalic sound to dissappear at.

mariobro · Post by **mariobro** » Thu Sep 16, 2004 11:02 pm

Microsoft says that focus groups preferred WMA sound files to MP3s in single-blind tests. They offer evidence, but hey, it's Microsoft...

There could be a bias against the WMA format. It's not THAT bad. That's why they do blind tests, so personal preferences don't come into account.

When people rip their converted mp3s onto an Xbox, they complain about sound quality. But rip a real RedBook audio CD and the results can be pretty satisfying. It's pretty comparable to mp3 files at a similar bitrate.

The source also matters. Files gathered all over the net over years are not a reliable yardstick for quality.

Gmc · Post by **Gmc** » Fri Sep 17, 2004 3:57 am

If your Xbox is modded, you can put higher quality WMA's on your Xbox using Virtual Xbox CD Ripper

BlackAura · Post by **BlackAura** » Fri Sep 17, 2004 6:08 am

Microsoft says that focus groups preferred WMA sound files to MP3s in single-blind tests. They offer evidence, but hey, it's Microsoft...

(Warning - techno-babble about sound codecs follows)

That's just because WMAs and MP3s work a little differently.

WMA is technically inferior to MP3. It's actually closer in complexity to MP2, and has similar distortion and filtering problems, but has something similar to MP3Pro added. It's basically a tiny extra bit of information about the upper frequencies that the encoder removed, and the decoder reconstructs the upper frequencies using random noise. Think of WMA as basically MP2Pro...

That's probably why WMA allegedly sounds better at lower bitrates. At lower bitrates, an MP3 encoder needs to strip more of the upper frequencies out of the sound. A WMA encoder does the same thing. You'll notice it a lot more with an MP3, because those upper frequencies are completely gone. WMA attempts to reconstruct those, so there's at least something there. Neither will sound anything like the original, and they both sound absolutely terrible, but most people would say that the MP3 sounds somewhat flat.

The problem with the upper frequency reconstruction is that it introduces an annoying metallic twang noise (or Microsoft's implementation of the encoder does). At around 128Kbps, a WMA will be only be using the reconstruction for the really high frequencies, and will be using standard encoding for the majority of the signal. As a result, the metallic sound mostly vanishes.

Some other codecs, like MP3Pro and AACPlus, use the same technique. However, the standard encoding can handle higher frequencies better than the standard part of WMA can, so the high frequency reconstruction isn't used as much, especially in the case of AACPlus. AAC doesn't really need the upper frequency reconstruction at all, because it can handle the high frequencies pretty well. As a result, you don't get the same metallic twanging sound as you do with low bitrate WMAs. There is still some distortion, and it doesn't sound much like the source, but it works better than WMA does.

Microsoft probably also used the crappiest MP3 encoder they could find. Probably the MPEG reference encoder, or more likely one of the commercial MP3 encoders based on it. LAME does a far, far better job than WMA at medium bitrates, because it doesn't distort the sound as much, and doesn't sound that bad at lower bitrates.

To be fair to them though, their newest encoder (WMA 9) is a vast improvement. The metallic twanging sound is reduced quite a lot. Of course, the Xbox doesn't use that encoder. I think it uses the standard WMA 8 encoder. They're actually the same format, so you can rip tracks to WMA 9 on a PC and copy them onto your Xbox hard drive, and they'll play fine. Assuming it's modded.

If you want to encode something at the same quality as the Xbox, use Windows Media Player 8, and rip to 96Kbps. If you use Windows Media Player 9, you'll be using the later encoder, which doesn't sound quite as bad.

If you want to try some comparable codecs, try the AAC encoder from Nero 6 in AAC+ mode at 96Kbps, MP3Pro at 96Kbps, and Ogg Vorbis at around 96Kbps. None of them sound like the source. AAC+ and MP3Pro have similar effects to WMA, although they're less noticable. Ogg Vorbis actually makes some of the upper frequencies louder than they were in the source.

DjB · Post by **DjB** » Fri Sep 17, 2004 8:33 am

Thanks for the help guys. Much appreciated. Oh and BlackAura, that was a nice read

perry · Post by **perry** » Fri Sep 17, 2004 11:34 am

BlackAura, that was a nice read