Working with maximum bitrates

[tommillard81]

Hi everyone, wonder if there's any experts who can help me out?

 

I have a new car with an SD card slot which will allow me to play MP3s or AACs through it, so I'm interested in putting my library on a card or two to enjoy while I drive.

 

I'm more than happy with the quality the 256kps AAC encoding that iTunes produces when I import a CD, and a lot of my music files are iTunes purchases too. The problem I'm having is that the car's audio system has a maximum bitrate of 320kps and won't play tracks where the peak exceeds this. Many of the songs imported into iTunes from CD exceed this maximum at points in the track, and about 5% of the music purchased on iTunes does as well ( I use an app called MediaInfo on my mac to check these maximums).

 

Would I notice any difference in quality if I imported my music as 320kps cbr MP3s, and converted my purchases to this format too? Or is there a better way to run through my library and clip the maximums of any tracks that exceed 320kps at any point?

 

Don't want to needlessly re-encode my music as quality will degrade and a lot of it is fine to start with anyway.

 

Hope you can help!

 

Tom.

[mwheelerk]

I do not use mp3 or AAC for importing CDs into iTunes but I seem to remember as I was learning to use iTunes there was a VBR (variable bit rate) setting in Import Settings for some of the lossy codecs. You might check your import settings under preferences in iTunes to make sure this is not selected.

[tommillard81]

Yes, that's right. I can encode to 320 mp3 and that imposed a hard limit that makes the tracks play fine. AAC with vbr turned off still allows the bitrate to wander over and above that important 320 threshold.

 

I've no problem encoding CDs at mp3 320 if the quality will be ok? I guess I'm more after a tool that can scan my library and flag up anything with a maximum peak bitrate of more than 320. Does such a thing exist?

[John]

 

I've no problem encoding CDs at mp3 320 if the quality will be ok?

 

With iTunes you can just make a copy of your lossless library at any rate you choose (I use 192k for the car) put the lower res versions in a separate playlist and then dump that playlist onto your SD card or USB stick. (Use doubletwist to copy the playlist).