Comparison of MP3 to MP4 Bitrates

2009-05-05 06:51:01

Now I know this has probably been done to death but I would like to get some reasonable idea.

This is my understanding and please correct me if I'm wrong.

The codec mp4 compresses better than mp3 so you can get a similar quality with a smaller file size

So assuming you use good codecs, what would be a similar conversion for each format.

For instance, if you use a variable bit rate and a good coder like Nero for AAC and LAME for mp3 and a VBR what would you need to get comprable file quality

Example:

Like if you use mp4 at 192 vbr this would be similar to mp3 at 320 vbr. Now I don't know if that is even close, I'm no audiophile at all. I'm just trying to get an idea.

Again I realize a bad mp3 codec or a bad mp4 codec can make all the difference. But lets say you have good codecs for mp3 and mp4

Basically it would be like saying, if you want to save disc space instead of using mp3 at 320 vbr use mp4 at XXX vbr and you'd save space and have approximately the same quality.

I would be referring to general pop music.

I ask this as I often help people with software and none of them need exact numbers or are even audiophiles, they just want a general idea on how to save a bit of space while getting similar quality.

Thanks

Comparison of MP3 to MP4 Bitrates

Reply #1 – 2009-05-05 07:08:40

The difference is only on mp3 problem tracks. The differences at bitrates >= 160k should be marginal. At sub 128k AAC is a clear winner.

Comparison of MP3 to MP4 Bitrates

Reply #2 – 2009-05-05 19:55:24

Wikipedia says "Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at many bit rates."

As shadowking said, at higher bitrates there will be no audible difference.  Above the "transparancy threshold", the MP3, AAC, and original WAV will all sound identical in a blind ABX test.  i.e. It's hard to compare 320kbps MP3 to an equivalent AAC bitrate, since 320kbps MP3 is usually going to sound identical to 240kbps MP3, etc.

At lower bitrates there will be a quality difference, and I would assume the lower you go, the greater the sound quality difference.  (I have not done any tests... I've never used AAC.) 

The quality difference will depend on the program material, and the different encoders might introduce different artifacts.  So, there is no single answer to what bitrates give you "equal quality".

However, there are bitrates/settings that are considered "good enough" (transparent) for most program material.  Here are links to the Hydrogen Audio Recommended MP3 (LAME) settings and Recommended AAC (Nero) settings[/u].



BTW - I understand that the terminology "320 vbr" is no longer used with MP3, since with vbr the actual final (average) bitrate depends on the program material.