[bigshot]

You can have your cake and eat it too with AAC. It's MP4 technology, which beats the pants off MP3.

 

[julian67]

It's MP4 technology

This is almost completely meaningless and it is misleading. MP4 is not a technology, it is a specification for a container. An MP4 file can contain mp3 or even mp2 audio (also other types of audio, video, metadata and subtitles). Additionally AAC audio can be contained in containers other than mp4, for example matroska, flv or 3GP.

But AAC is probably superior to MP3 in every way except CPU load when decoding on low powered devices. I can't think of any other area where MP3 is better except perhaps in the variety and ease of use of command line tagging tools.

 

[bigshot]

MPEG-4 isn't just a container. It's a set of compression specifications.

http://en.wikipedia.org/wiki/MPEG-4

AAC is a codec that uses MPEG-4 specifications for audio.

http://en.wikipedia.org/wiki/Advanced_Audio_Coding

 

[julian67]

MPEG-4 isn't just a container. .....

You didn't state MPEG-4, you stated MP4. The terms are not synonymous or interchangeable.

from http://en.wikipedia.org/wiki/Mp4

MPEG-4 Part 14 or MP4 is a digital multimedia format most commonly used to store video and audio, but can also be used to store other data such as subtitles and still images.

from http://en.wikipedia.org/wiki/MPEG-4 (my italics)

MPEG-4 is a method of defining compression of audio and visual (AV) digital data.
...
AAC (Advanced Audio Coding) was standardized as an adjunct to MPEG-2 (as Part 7) before MPEG-4 was issued.

So it's not even accurate when you state that "AAC is a codec that uses MPEG-4 specifications for audio." because the codec came first and was then incorporated into the MPEG-4 spec.

Anyway all this belongs in a different place such as Wikipedia where it already exists and anyone who cares can inspect and read for themselves. The point everyone can probably agree on is that AAC is superior to MP3 in almost every way if one avoids very low spec or old playback devices.

 

[bigshot]

Your post makes absolutely no sense. The page you linked to says .mp4 is the filename extension for mpeg-4, and has a header that says "History of MP4" with a description of the history of MPEG-4. If it quacks like a duck...

 

[julian67]

Your post makes absolutely no sense. The page you linked to says .mp4 is the filename extension for mpeg-4

The wikipedia article states:

....filename extension for MPEG-4 Part 14 files is .mp4, but many have other extensions, most commonly .m4a and .m4p.

(my italic)

Under the title "History of MP4" the first words of the first sentence are:

MPEG-4 Part 14 is an instance of more general

.

The author of the article has clearly been careful to distinguish the MPEG-4 specification/standard from the MP4 container AKA MPEG-4 Part 14. If you feel this makes no sense or is incorrect then you are free to edit the Wikipedia page and offer your correction, improvement, or clarification.

 

[Empire1]

Quote:

Going back to your original post, in general, 320kbps files in either AAC or MP3 are quite excellent, if they were encoded from an original uncompressed source.  It's generally true that most people can't tell those files from the original.  Files obtained from legitimate sources have their roots in the original CD, so the likelihood of getting a "bad" one would be confined to corrupted files which usually have catastrophic defects.  I have had corrupt files from several sources, but most sellers will let you re-download before refunding your money if you run into a glitch.  The encoding process for these files is fairly controlled, unlike the illegitimate sources, which could be anything, encoded by anybody, possibly more than once.

 
 
Quote:

Also, it's possible to convert a 64 or 128 kbps file to 320.  So a non-legitimate source could even be that.

 
Would there be any way for me to identify 320 kbps mp3 files that have been encoded from lower quality files?
 
Wouldn't there be a difference in file size of 320kbps ripped from CD and 320 kbps coverted from a lower bitrate?
I mean, most of my 320kbps mp3s are around 8-10 MB. I think you couldn't increase the file size of a lower bitrate song even if you encoded it to 320kbps? I'm just making assumptions here though. 
 
Right now out of my entire library I have maybe around 150-180ish songs that are 320kbps mp3 files that have been downloaded from illegitimate sites (such as mp3skull). I'd rather not replace them all with better quality files if possible, especially if there is no perceptible difference in audio quality. 
 
If it's worth mentioning, I'm looking at gear like the HD600s to maybe buy within the next few months. 

 

[jaddie]

Quote:

Originally Posted by Empire1 /img/forum/go_quote.gif
Would there be any way for me to identify 320 kbps mp3 files that have been encoded from lower quality files?

You might spot re-encoded files if they have been low-rate files at some point by looking at the total spectrum of the audio contained.  Low-rate files won't have much of anything above 15KHz, where high-rate files that have never been anything else should have content up to 20KHz or so.  
Quote:

Wouldn't there be a difference in file size of 320kbps ripped from CD and 320 kbps coverted from a lower bitrate?
I mean, most of my 320kbps mp3s are around 8-10 MB. I think you couldn't increase the file size of a lower bitrate song even if you encoded it to 320kbps? I'm just making assumptions here though. 

Not much, if any difference.  You can't really spot them that way.
Quote:

Right now out of my entire library I have maybe around 150-180ish songs that are 320kbps mp3 files that have been downloaded from illegitimate sites (such as mp3skull). I'd rather not replace them all with better quality files if possible, especially if there is no perceptible difference in audio quality. 
 
If it's worth mentioning, I'm looking at gear like the HD600s to maybe buy within the next few months. 

Well, let me wave my finger and say, "For Shame!" But anyway...
 
You'll always wonder where and how they came to be, and even if you can detect that they were re-encoded, how they were encoded may always remain a mystery.  So, you have to weight the cost of replacement with (legitimate!) high rate files, purchase the stuff on used CDs (cheaper per-track cost than buying .mp3, by the way) and ripping them yourself under known conditions and methods, or living with your files of questionable parentage.  If you're considering high quality playback devices, you'll want the best files.  You might start with your all-time favorites, buy the CDs used on Amazon for cheap, and get some high-rate files for your new gear.
 
You can always buy used CDs, rip them, then re-sell the CDs.  Net cost of the files is darn near zero, and though still of questionable legitimacy, you'll have great audio.  But you didn't hear that idea from me.  I was never here.

 

[julian67]

Would there be any way for me to identify 320 kbps mp3 files that have been encoded from lower quality files?

Yes, if you have the lossless original you will probably be able to do it by ear. Otherwise...maybe.

Wouldn't there be a difference in file size of 320kbps ripped from CD and 320 kbps coverted from a lower bitrate?

No. 320 kbps both describes the data rate and determines the size.

I mean, most of my 320kbps mp3s are around 8-10 MB. I think you couldn't increase the file size of a lower bitrate song even if you encoded it to 320kbps?

Yes you could. See above.

Right now out of my entire library I have maybe around 150-180ish songs that are 320kbps mp3 files that have been downloaded from illegitimate sites (such as mp3skull). I'd rather not replace them all with better quality files if possible, especially if there is no perceptible difference in audio quality. 

If it's worth mentioning, I'm looking at gear like the HD600s to maybe buy within the next few months. 

There is an old saying: "Garbage in, garbage out." Expensive kit won't improve bad files, in fact the better the kit the less satisfied you will be with bad files.

 

[julian67]

You can always buy used CDs, rip them, then re-sell the CDs.  Net cost of the files is darn near zero, and though still of questionable legitimacy, you'll have great audio.  But you didn't hear that idea from me.  I was never here.

+1

Used CDs are ridiculously cheap. Last week I bought a used CD for a penny and paid £1.26 postage and another for £3 + £1.26 delivery. Discs and booklets are pristine and neither is a budget disc. This is pretty normal. My local CD shop has lots of used CDs for £2.99. In the last few years I have bought an awful lot of used CDs, lots of them costing only £2 or £3 including delivery and they are almost always in very good condition and I have only bought one which was scratched badly enough that I couldn't make a secure rip. Legal, high quality music can be extremely cheap these days.

edit: I keep my CDs though

 

[Empire1]

Quote:

You might spot re-encoded files if they have been low-rate files at some point by looking at the total spectrum of the audio contained.  Low-rate files won't have much of anything above 15KHz, where high-rate files that have never been anything else should have content up to 20KHz or so.  
Not much, if any difference.  You can't really spot them that way.
Well, let me wave my finger and say, "For Shame!" But anyway...
 
You'll always wonder where and how they came to be, and even if you can detect that they were re-encoded, how they were encoded may always remain a mystery.  So, you have to weight the cost of replacement with (legitimate!) high rate files, purchase the stuff on used CDs (cheaper per-track cost than buying .mp3, by the way) and ripping them yourself under known conditions and methods, or living with your files of questionable parentage.  If you're considering high quality playback devices, you'll want the best files.  You might start with your all-time favorites, buy the CDs used on Amazon for cheap, and get some high-rate files for your new gear.
 
You can always buy used CDs, rip them, then re-sell the CDs.  Net cost of the files is darn near zero, and though still of questionable legitimacy, you'll have great audio.  But you didn't hear that idea from me.  I was never here.

 
 
Quote:

+1

Used CDs are ridiculously cheap. Last week I bought a used CD for a penny and paid £1.26 postage and another for £3 + £1.26 delivery. Discs and booklets are pristine and neither is a budget disc. This is pretty normal. My local CD shop has lots of used CDs for £2.99. In the last few years I have bought an awful lot of used CDs, lots of them costing only £2 or £3 including delivery and they are almost always in very good condition and I have only bought one which was scratched badly enough that I couldn't make a secure rip. Legal, high quality music can be extremely cheap these days.

edit: I keep my CDs though

 
~sigh~
 
Was afraid you guys would say that. I guess it's time to upgrade my collection. I've actually never considered used CDs before. Looking at Amazon, I'm quite surprised at the (relatively) affordable prices. I'm kind of scared though... won't scratched CDs affect the file quality?

 

[bigshot]

If a CD plays it plays. If it doesn't, Amazon A to Z guarantee will give you a refund.
 
But I don't see any reason to replace a file that sounds good. Just listen to the music and enjoy it.

 

[Empire1]

Quote:

If a CD plays it plays. If it doesn't, Amazon A to Z guarantee will give you a refund.
 
But I don't see any reason to replace a file that sounds good. Just listen to the music and enjoy it.

 
That's a valid point. I may choose to keep most of the mp3 files I have now, as long as the quality is good.  
 
I feel a bit uneasy about the possibility that some songs could have been converted to 320kbps from a lower bitrate. I think you or some other user mentioned checking spectrum or something using Spek/Spectro? I've found the webpage but I'm not sure if I could make sense of the information given to me by the software

 

[moriez]

Spectro is easier to use as you can make the frequency cut off visible. Basically, have the program analyze the file. If it's around 16khz then it's very likely a transcode.
Be aware that some albums have nearly no high frequencies and could show 16khz or even less while being encoded perfectly. Noticed this mostly with electronic ambient.

 

[jaddie]

Quote:

edit: I keep my CDs though

Yup, me too. Seems stupid not to.  But I keep them in storage, not really all that accessible.