[M4IF Technotes] Suggest some MPEG 4 Encoders

[Stephen McGrath]

Hello, everyone.
I beg to differ on the statements made here about lossy codec quality,
particularly about AAC at 128k. Subject to the usual provisos about what
you are looking for, quality of playback system, etc. etc., there is
definitely a noticeable difference between source and AAC at 128 or even
256.
Please remember we are talking about audiophile quality here - this was
the context of the original question. For mass market consumption,
listening over a mass market PC soundcard with cheap speakers, etc. -
sure, the output is indistinguishable. But if you invest in a good audio
playback system, then there is absolutely a noticeable difference. I am
not claiming that everyone will hear it, but I am claiming that trained
listeners and/or audiophiles will. "Trained listener" here does not
necessarily mean someone who does this professionally, just someone who
has listened often enough that they come to realize what they are
hearing and recognize the distortions.
Which is fine, there is nothing wrong with this. This is why there is a
much larger market for $400 bookshelf audio systems than for audiophile
gear. To each his needs. Just don't claim there is no difference!
I can personally back this from 15 years of working in speech and audio
compression, and much longer being an audiophile (which appears to be an
incurable disease!) And yes, I have done this through double-blind
testing. Many times. Repeatably. :-)
Stephen
Ben Waggoner wrote:
> 
> on 6/18/02 11:46 AM, Jay W. McGuire at PigsOnTheWing   mac.com wrote:
> 
> > I'm an audiophile and am planning to buy Apple's new Xserve w/480GB of file
> > space to store all of my CD audio files. Can anyone tell me if there's any
> > advantage, besides reclaiming additional storage space, to going with AAC
> > over WAV files? I'm interested in the best possible sound quality and have
> > been using Monkey's Audio (lossless) on the PC but, so far, there is no
> > support for APE files on the Mac. I listen to music constantly and am also
> > concerned about what kind of stress that puts on a computer. Since AAC files
> > would be much smaller than WAVs or APEs, will they result in less stress
> > (thru less frequent/smaller reads?) on my hard drives?
> 
>     AAC can deliver great quality, but it isn't a lossless codec.  I suppose
> lower data rates would mean slightly less drive wear, but probably not
> enough to fret over.
>     Myself, my jukebox is 130 GB of 320 Kbps MP3 files, which is overkill. I
> probably would have gone with lossless, except the integration and ease of
> use of iTunes is just so phenomenal.
> 
> > I'm playing around with QuickTime 6 right now and have made a couple of AAC
> > files. I'm a bit confused as to what kind of settings I should be using,
> > though. Like I said, I want the best possible sound quality, so does that
> > mean I should be encoding at 256kbits/second (the highest QT6 will go)?
> > Also, do I want to select any of the streaming options? I'd be accessing the
> > Xserve's AAC files from one or more Macs located around the house, but
> > that's not streaming, right? And what about the setting for 'ISMA'
> > compatibility? Do I want/need that if I'm not streaming? And what about
> > "tags?" Any attempts I make to enter "Artist," "Album," "Full Name,"
> > "Copyright," "Track," etc., result in only the "Copyright" information being
> > kept after the file is saved. Is this a limitation of the "Public Preview"
> > for QuickTime 6? Or are these things not supported in an AAC file?
> 
>     Beyond 128 Kbps, you are very unlikely to be able to tell the difference
> between source and output with AAC (like 256 Kbps MP3).  I encoder higher
> because I use my archive as a master to converting to other formats, so even
> imperceptible errors can cause generation loss, which I want to minimize.
> 
> > Who's code is being used by QT6? I think I read somewhere that it was from
> > Dolby? Is this true? Is any one implementation better than another? I hear a
> > lot of talk about a "Psytel" encoder on the PC. Is its AAC encoding any
> > better or worse than QT6's AAC? I tried to play the Psytel demos on the
> > author's site with QT6...all I got was silence. Are there compatibility
> > problems when going from one encoder to another?
> 
>     Dolby is a principle creator of AAC.  Apple may very well have licensed
> it from them.  I don't know that there is a significant difference in AAC
> encoders from different vendors, like there used to be with MP3.
> 
> > I used LAME at its highest 320k setting to create MP3s before I decided to
> > store uncompressed WAVs and/or use the lossless Monkey's Audio compressor
> > for best possible sound quality. Will I be happy with the quality of AAC? Is
> > it really as good as they say?  Or should I stick with WAVs or wait until
> > someone comes up with a Monkey's Audio decoder/player for the Mac?
> 
>     You'll need to do some tests yourself to see what your preferences are.
> I'd think high bitrate AAC should be just fine for listening.
> 
>     My hope is that .MP4 AAC audio files will eventually displace MP3.
> 
> Ben Waggoner <http://www.benwaggoner.com>
> Compressed Video Consulting, Training, and Encoding
> 
> Cleaner Tutorial:   http://www.saferseas.com/navseries/adclean.html
> My Book:            http://www.benwaggoner.com/books.htm
> Compression Books:  http://www.benwaggoner.com/bookshelf.htm
> 
> Compression classes at Stanford, July 15-19 and August 12-16:
> http://www.digitalmediaacademy.org/courses/videocompress.html
> 
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