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View Full Version : Partition music library? Want to transcode into smaller files for iPhone




rawdawg
Feb 16, 2009, 06:13 PM
Being a hobbyist audiophile I understand a music file that has been transcoded is of poor quality. Personally I prefer my music ripped at V0 Mp3 through LAME. It gives me, IMO, the best compromise between quality and size (though I still have many with a 320 bitrate).

I would like to be able to have more music on my iPhone. I do not want to purchase a bigger iPhone. I do not want to manually manage my playlists either. I do not want to re-rip all my CDs again at a smaller file size.

I've read that for portable use (i.e. listening to while driving, on the subway, or in an airplane) V0 can be overkill. That high quality is unnecessary with such background noise. Specifically I read (and unfortunately I don't remember where) that you can get away with lowering the sampling rate (not bitrate) to 16khz, although that may be wrong, sounds very low.

What I want to do is transcode my existing files to a smaller file size. In the last paragraph I read that lowering the sampling rate is an option. Would this be more effective for my needs than lowering the big rate? I guess I'm curious about my options. I do notice that at least in iTunes AAC (should I choose that end format) does not offer many options for a lower sampling rate. In the past I've stuck with Mp3. Should I consider AAC for my situation and why--is it really that more efficient?

My other question is how would I then handle my newly made duplicates and syncing my iphone to my computer. A few months ago I tried doing this and noticed quickly by making transcodes I created duplicates in my library and my playlists and everything now has cluttery duplicates. Unless I can make these transcodes invisible except for managing my music on my iPhone I don't know how to now sync my iphone with iTunes.

Any expert advice!? Much thanks in advance!



rawdawg
Feb 18, 2009, 10:29 AM
Guess no one has ever thought about doing this.....

Too bad.. Makes sense... Have a good version at home and a much smaller file to take on the road packing in all the music you can need...

mzd
Feb 18, 2009, 11:13 AM
i can't really comment on changing the sample rate because i haven't experimented with it.
i would say you could definitely go as low as 160 VBR AAC for portable devices though. in fact, i usually rip at 128 VBR AAC (used to use 160 but my iPod was getting full). but i'm not audiophile. (though i am a musician so i do pay attention.)
anyway, 160 AAC will definitely bring the 230 (V0) mp3 down in size.

in iTunes, you can have multiple Libraries. this sounds like the best option for keeping multiple versions of songs. (or you can create different user profiles, but that seems like maybe overkill for this task.) to create (and select between) a new Library, hold down the Option key when you launch iTunes. add the "iPhone" Library to the new one.
it will require some manual file management though. if you are transcoding with iTunes, you will have duplicates. you will need to remove the duplicate from your regular HiFi Library (move it to a temp folder on the desktop or something). then when you restart iTunes with the iPhone Library, add the smaller songs in.
it is a bit of a hassle and you have to manage the files a fair amount, so if you aren't really comfortable doing that it may not be the best solution. but i'm not sure how else you could do it without duplicates in your main Library. (i.e. a smart "HiFi" playlist and a smart "iPhone" playlist.)

rawdawg
Feb 20, 2009, 10:45 AM
well that will definitely get me started!

thanks for the advice!

Consultant
Feb 20, 2009, 11:35 AM
There are dozens of threads.

There is a script available for those who has loseless music
and convert them to smaller size for iPods or iPhones,
while keeping the original files and playlists.

lostless
Feb 20, 2009, 01:39 PM
Do not change the sample rate. Using the nyquist sample rate, the highest frequency is 1/2 the sample rate. So your max frequency would be 8khz sampling at 16khz. The human ear hears up to 20khz most people can't hear past 17 or 18khz. CDs as well as downloaded music is sampled at 44.1khz which allows up to 20khz plussa bit of breathing room. So to get an idea how that will sound, throw the audio file into itunes and turn off all frequencies above 8khz.

To get a smaller file size, lower the bit rate, not sample rate. A sample rate of 16khz at 320kb/s is still thesame size file as a 44khz file at 320kb/s. I find aac at 160kb/s to sound pretty good.