Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[InflatableMouse]

Disregard the fact that most people can't even hear the difference of a good mp3 on 192kbps, its not a discussion I want to have here.

If we consider 192kbps 'transparent' for a 16/44.1 audio CD, how would we encode 24/192 to achieve similar transparency with a lossy format? In mp3 land there's no such thing as 16 bits or 24 bits  ?

How would we encode this to mp3 .. if that is possible at all?

The compression factor on the 192kpbs mp3 is roughly 7.3. Do we simply apply that same number to the 24/192? I would encode to 630kbps?

That may sound really dumb but I have no clue how mp3 compression really works (tried reading about it but it just hurts my brain). I read it applies low and high pass filters, does that mean 24/192 would basically be cut off to the frequency range of a CD?

_{PS. couldn't really find a proper place for this Q, feel free to move it if need be}

[craigmcg]

As to how, I had never tried doing something like this so I highlighted a 24/96 FLAC album (about 950 MB) in my library then right clicked to choose Library tools-Convert format. I then selected Options to make sure I didn't delete my source files and sent the new files to a different folder. I then clicked the Encoder button at the top left of the window selected MP3 encoder and custom setting (I prefer VBR) then changed the V4 default to V0. I clicked okay then start. About 90 secs later I had an album of 16/48 mp3s that were about 86 MB in total. If you want to see the details, select the files in Windows explorer,then right click on properties- Audio properties to see the sample size (16) and sample rate (48).

I assume that 24/192 files can be converted the same way.

I can't even begin to explain the technology behind the conversion itself but it was easy to do.

[lowjoel]

From my cursory glance at articles on the Internet, coupled with some software engineering background I've got, mp3 does not support bitrates over 320kbps (the specification only defines bitrates up to 320kbps, even if LAME supports more than that). In addition, only sampling rates up to 48khz are defined in the standard (so 24/192 audio will have to be resampled to 48khz.)

As for why bit depth is not an issue, http://www.hydrogenaudio.org/forums/index.php?showtopic=55336 is probably useful. I'm no physicist, but I'm going to try to distil that thread. Basically we are used to lossless data where each sample corresponds to a fixed position in time and each sample stores a discrete sample. But mp3 does not have that requirement (like we said, it's lossy -- samples can be dropped if the codec perceives it indistinguishable) and so bit depth in the normal sense does not apply. I think Matt would be the best person to explain this... having wrote APE and all.