Skip to main content ↑ ↓

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: "Upconverting" AAC/MP3 Files (Read 5159 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

"Upconverting" AAC/MP3 Files

I know that, if possible, you should never transcode from one loss format to another...but, if you have to do it, doesnt it make sense to do it to as high a bit rate as possible, to minimize loss? 

I have a number of 128 AAC files I need to convert to MP3 (I don't have access to the original CD's).

Now, I know the old rule of thumb that it's a "waste of space" to convert at a higher bit rate than the original. Obviously you're not going to improve on the quality of the original going from one lossy format to another....I understand that any transcoding from lossy to lossy will result in the loss of quality.

BUT....doesnt it make sense, in order to minimize quality loss, to convert to the highest lossy  bit rate possible?

Lets say I have a 128 AAC file and convert it to 128 MP3...there's going to be a lot of information lost.

On the other hand, wouldnt converting the 128 AAC file to 320 MP3 sound better than if I just converted it to 128 MP3?  We are losing less information that way, right? Obviously, even converting to 320 MP3 will still be a step down from the original 128 AAC file...but NOT as much of a step down as if I converted to 128 MP3, right?

And of course this logic would apply if you were just going from AAC to AAC.

If you copied a 128 AAC file using a Apple Lossless, you'd have an file that is the same quality as the original...so doesnt using 320 KBPS yield a better quality than converting to 128?  LESS information is lost in the "upconversion", correct?

Or is my thinking fundamentally flawed here?

"Upconverting" AAC/MP3 Files

Reply #1 –
Theoretically:
You will get the best quality by:
  Transcoding lossy -> any lossless format. (This will provide quality equal to the original lossy file)

You will get pretty good quality by :
  Transcoding lossy -> a higher bitrate lossy codec. (This will give a file as faithful to the original lossy file as is possible within the constraints of the encoder settings and format.)

You will get the worst quality by:
  Transcoding lossy -> a lower bitrate lossy codec. (This will give a file that is faithful to the original lossy file as is possible within the constraints of the encoder settings and format, and making additional compromises for the smaller bitrate/filesize)

Practically:
None of this really matters! The only way you can really tell what kind of quality you are getting is through listening to the files, and doing some ABX testing. It is entirely possible that transcoding to a lower bitrate will still give a file that sounds good enough to your ears and is still nice and compact.
In the digital audio world its nice to get validation from the facts and experts, but ultimately the only way to get real satisfaction is by listening to the audio and deciding whether or not it sounds faithful enough to the original to your ears.

Have a nice day!

"Upconverting" AAC/MP3 Files

Reply #3 –
Quote from: audioadam on
Transcoding lossy -> any lossless format. (This will provide quality equal to the original lossy file)

This will also encode the error from quantization of the lossy data to a given bit depth, unless you're using floating point files.

"Upconverting" AAC/MP3 Files

Reply #4 –
Quote from: j7n on
Quote from: audioadam on
Transcoding lossy -> any lossless format. (This will provide quality equal to the original lossy file)

This will also encode the error from quantization of the lossy data to a given bit depth, unless you're using floating point files.




Well yes, but so does playback (don't forget lossy files get decoded on playback). This isn't something to worry about.

"Upconverting" AAC/MP3 Files

Reply #5 –
So it's pretty much what I though....thanks for all the feedback!