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View Full Version : AACenc vs iTUNES/QT



Larry!
10-28-2004, 06:42 AM
Which one to choose? I tried both at 192 kbps, but mp3 at 320 kbps still sounds better =/.

xoas
10-28-2004, 11:17 AM
mp4/AAC are both lossy formats. They should give better quality than mp3 at identical bitrates (ripping from the same source) or you should be able to compress a bit further than mp3 to maintain the same level of quality. You will have to do your own listening test to figure out what sounds best to you. Unless you have an urgent need I would not recommend bothering to convert mp3 files to mp4 or AAC.
As to AACenc vs. QTmp4 both use AAC encoding in an mp4 container. If I were using iTunes or an iPod, there might be a slight advantage to using the QT encoder. Otherwise, you would have to check them out and see which does best given your particular priorities (speed, quality, controls). The QT codec does require you to have a REGISTERED version of QuickTime (which I believe means having QuickTime Pro which means parting with real money unless you already have the program).

Best wishes,
Bill Mikkelsen

Larry!
11-17-2004, 08:50 AM
Ok but how about PsyTEL AACenc. It's quite slow, but creates good quality files.

xoas
11-17-2004, 06:50 PM
Larry!
The same principles apply. If you are ripping tracks the mp4/aac codes will give equal or better results when compared to the same tracks ripped to mp3 at the same settings (frequency, bitrate, channels).

If you have wma or mp3 files you really don't want to convert them to another format unless you have a pressing need to (say you have wma tracks and wish to burn a disc for your car player which supports mp3 but not wma). This is because when you convert these files, you are converting either a lossless format (which will take up more space) or to a lossy format (which mp4/aac are, as is Ogg, mp3, Musepack, WMA) in which case you will lose audio information (even though, with good lossy formats at high bitrates the differences may be inaudible).

I agree with your observation regarding the PsyTEL AACenc codec. It does a good job. Spoon and others have recommended the FAAC encoder and it is quicker. The dMC FAAC codec has the limitation that you are not always sure about the bitrate and frequency of the file you are creating whereas with the PsyTEL AACenc codec you certainly do. While I have toyed with the PsyTEL AAC, PsytTEL mp4, FAAC and Nero mp4 codecs, I must admit to not noticing a great deal of difference between them in terms of the resulting audio quality, but I have not tried to do any detailed listening tests to compare them. There is a link to an earlier listening test comparing a number of these codecs at Codec Central.

The real question is one of what your priorities are and which format and codec best suits those needs. So if you are pleased with codec X, use it. Someone is always going to come along with an opinion that codec X is mediocre and codec Y is the one to use if you REALLY know what you are doing. They may even trot out evidence in the form of wave-form analyses or listening tests, or expert opinion. Be open to trying codec Y if you like and switch if you like, but if you are satisfied with codec X stick with it. There are SOME codecs I have no interest in trying (Atrac/Atrac3 and RealAudio to name two) but even they do have their place.

So if you feel satisfied with the PsyTEL AACenc. codec and feel like you have given at least some consideration to the others (especially the FAAC codec) then go ahead and use it. If you have some special encoding need (like encoding for a cell phone) you may want to get an opinion as to whether any particular codec is better suited for those particular needs, if you have any questions.

Best wishes,
Bill Mikkelsen

Larry!
11-18-2004, 05:45 AM
10x xaos for such a detailed answer. Of course, it's obvious to me, that conversion from one lossy format to another(lossy) will cause some degradation in sound. But my
point was, actually, to convert from higher bitrates(like mp3 320-192) to more advanced format, which would be able to preserve quality at lower bitrate to save some space, when i need to fit an .avi file on 700mb cd, for example. There's 2 more interesting things. A few years ago i red an article about mp3 encoding algorythm. At some point it was saying, that at highest bitrate(320kbps) mp3 uses no quantization, only logical compression, which means it's lossless at this bitrate. Is it really so? And another rumor says, that aac is about 30% better quality to mp3, e.g., 128kbps aac(lc) is equal to 160kbps mp3.

...True, faac is greatly improved these days, even though there's a lot of another great formats, looks like mp3 will stay on top for another decade or two ;)

xoas
11-18-2004, 06:19 AM
My understanding is that mp3 is lossy even at 320 kbs. although whether this would be meaningful in a listening sense is very questionable. I have not read of or heard the item about aac vs. mp3 but it sounds to be about right. I have not, however, done testing to confirm this, I would advise that you try converting a few files to different aac settings to confirm this before acting on it because sometimes what people say may be a bit inflated. For example, WMA at 64 kbs is often said to be equivalent in quality to mp3 at 128 kbs, whereas my experience is that generally WMA needs to be at 96 kbs to be equivalent to mp3 at 128 kbs. So don't be afraid to experiment and research. (Just don't forget about enjoying the music).

And yes, when you have applied situations that require this, you certainly can make modest compromises in quality. Be sure, if you are looking to reconvert to lower bitrates to do some experimenting with bitrates in the range you are interested in. For example, I know that mp3 at 256 kbs does not sound different to me than does mp3 at 320 kbs. That alone should improve compression by around 50% (if I recall correctly). Now if I had the ears, equipment, music and listening environment where this would make a difference, then I should prefer 320 kbs but I don't. I also don't have any special purposes for my audio files (I don't do sound engineering or professional recording, for example) that would lead me to have a special need to use 320 kbs.

Best wishes,
Bill Mikkelsen