" hi mike!
I was also really impressed by how MP4-audio sound (eg ACC audio). The cool thing I found too is that it doesn¥t seem to use much more CPU-power than MP3. That real good I reackon.

Will send some exact figures later, but I think on my DP500 G4 mp3 in QuickTime used around 15% CPU when mp4 was in the 10-15% range.

On the sidenote I don¥t think the MP4 videoencoder uses MP yet. Hope the final one does (I get faster encoding speed with Sorensson 3.1 than MPEG-4, both around 0.5x of realtime).
- Erik "

" Hi,
I just wanted to respond to a reader's mail comparing the quality of MP4 to MP3, as it may be misleading to some. First, the quality of the audiofiles depends on the encoder used. I would agree that iTunes at 192 kbps is bothersome, but using the latest LAME encoder on OSX (3.92) yields very good results at 192 kbps, especially using --alt-preset cbr 192. I agree that AAC in MP4 sounds great, in AVERAGE music I have a difficult time hearing differences at 160+ kbps (good equipment, ABX testing). However, where Apple's implementation of AAC fails miserably (the implementation in QT6 BETA doesn't use VBR, despite Apple's claims) is on test samples such as fatboy
(http://lame.sourceforge.net/download/samples/fatboy.wav).
Even at a bitrate of 256 kbps the sound is severely mangled. Also, the use of constant bit rates in the ogg vorbis qt plugin is not up to par (broken, doesn't always work properly and sounds horrible) so the comparison (if CBR was used) is not valid. VBR ogg vorbis with a quality of 5.0+ (avrg < 192 kbps) is basically transparent to most users even on difficult clips.
- KN
xlr8yourmac reader "

" I think the tests conducted by 'sandor' [in yesterday's news - see below-Mike] may be a little optimistic. First of all, he forgot to mention that with the current exporter, you can only create 32 KHz Low-Complexity Profile AAC mp4s at 96 Kbps, not 44.1 KHz Main Profile AAC mp4s.

I know I can definitely tell the difference between a 44.1 KHz 192 Kbps mp3 and a 32 KHz 96 Kbps AAC mp4 at this point. Apple's own AAC encoder is probably in alpha or very early beta stage right now anyway.

I think I'll stick to my "lame --alt-preset extreme" encoded mp3s for now, even though AAC looks very promising indeed.
--Eugene Chan "

(from a forum post)

" A reader at Xlr8yourmac.com had a little thingy on some reader who tested MP4 audio. His results were MP4 were glowing. I decided I had to try it.

I tried out MP4 vs MP3 in ultra high bit rate and mid range. I decided to use a track that I made myself in reason, which I've listened to bazillion times that I've scrutinized the utmost minor details. All tests conducted using Quicktime player (QuickTime encode mp4s, N2MP3 Lame for MP3s) and digital to my receiver using my Sony MDR-V6s

First I tried 96 kbps MP4. It sounded good but wasnít any MP3 192 kbps that the reader claimed. I noticed in a part, very distinctly distortion when a bass drum hit over the synth bass line, plus the bass line sounded slightly metallic. Highs sounded fairly good. I tested the 192 kbps MP3. Almost no distortion on the bass line and the highs sounded as good as the 96 kbps Mp4. The 128 MP3 was murdered the hi hats sounded like **** . MP4 at 96 kbps highs were the equiv. of a 160/192 and bass of a 128/160 MP3.

I then compared 256 MP4 vs 320 MP3 vs the source AIFF. Both the 256 kbps MP4 and the 320 kbps MP3 sounded great but still lacked the definition when the solo bass line and the bass drum kicked. Highs lost brightness in both, and strangely the MP4 still seemed not be as apt to handle the bassline as accurately as an MP3, although almost barely noticeable. I might later make a sound file strictly for testing this and upload various versions so anyone can test.

Conclusion
MP4 kicks the crap out of Mp3s at low bit rates but the edge falls off..
MP4 96 = Around 160 Mp3
MP4 196 = around 256 MP3
256 Mp4 (max quality) = around a 320 Mp3.
Greg G. "

(Original reader comments from the 6/6/2002 news page follows)

"hey mike, did this quick test.. i was wondering how likely mp4 would be to replace mp3, and did a little test of it. i picked the song i did because it had great highs and lows (normal mp3's destroy the lows at low rates, so i wanted to have plenty of lows and highs to test)

here are my results-

The Fugees-How Many Mics
Aiff - 45.2 MB - cd quality (cd audio)
MP3 - 6.1 MB - 192 kbps (sounds good)
MP4 - 1.8 MB - 56 kbps (drastic loss of highs)
MP4 - 3.1 MB - 96 kbps (sounds as good as 192 mp3)
MP4 - 6.2 MB - 192 kbps (close to aiff quality)
OGG - 6.2 MB - 192 kbps (warble of a 96 kbps mp3)

all encoding was done with QT 6 in OS X, ogg done with the QT plugin from sourceforge
(available here)

personally i cant stand an mp3 under 192 kbps, it sounds horrible to me. thus i didnt even test anything under 192 k for mp3's. ogg was horrible and large at 192, so i didnt bother testing less compression. mp4 is freaking awesome. 56 was too low for me, although i could see some people not noticing the loss of high trebles. 96 kbps mp4 could pass as a 192 kbps mp3 no problem, and at half the file size (3.1 MB compared to 6.1 MB) the 192 kbps mp4 roles out of my system as smooth as the aiff, and it is the same size as the mp3.

final conclusion-i want mp4, and i want it now = ) (my only question is concerning id3 tags...)
peace
sandor "