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iPhone 3Gs ALAC sample rate / 24-bit

post #1 of 9
1/1/10 at 9:06pm
Thread Starter 
I have a sizable collection of high-fidelity FLAC music, much of which is 96khz/24-bit rips from a friend's vinyl setup.

When converting the FLAC's to ALAC for iPhone 3Gs playback, what is the maximum bit-depth and sample rate I should use? I read the iPhone can only play sample rates up to 48khz, is that true? Would I need to resample the files prior to bringing them into iTunes?

Also, I have The Beatles in Stereo USB, which includes 24-bit 44.1khz FLAC files. I assume I should simply convert these to 24-bit 44.1khz ALAC's? When playing 24-bit files, does the iPhone output true 24-bit or does it first cut it down to 16-bit (which I assume would negate the advantage of using 24-bit files)?

Any advice on this topic is very greatly appreciated... I know this may be a tricky topic. I use the iPhone 3Gs because it is, obviously, extremely convenient and because I also feel it has very good sound-quality. I listen using the Triple.Fi 10vi (walking/subway/travel) and using Shure SRH840's (office/home).
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post #2 of 9
1/1/10 at 10:05pm
I was going to ask *exactly* the same question!

I've done my research today (google + forum search) for few hours and this is what I've found so far:


1. sadly, iPhone/iPods won't play files with higher sampling rate than 48kHz - (please, correct me if I'm wrong)!
I *wish* it could play 96kHz files, but they say even iTunes won't allow you to transfer proper 24bit 96kHz audio to iPod/iPhone. The DAC of the iPhone is capable to play that, the firmware/electronics probably not. This explains "apple" Beatles Mono Remasters at 24bit 44.1kHz "only"...


2. I see no reason for the iPhone DAC to downsample 24bit as it can operate in 24bit/48kHz mode just fine.

3. you can't use dbPowerAmp for FLAC-> ALAC conversion, as it can't handle 24bit (uses some nero codec?).
And you must first make .wav files anyway (via cmd line), then use something like IzotopeRX to dither them to 48kHz and then "iTunes" them to ALAC. Any advice on this cumbersome process is welcomed!

4. any software out there that would "just tag" newly created ALAC files when I would present it FLAC source? because going through the .wav step I'm loosing all tags...
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post #3 of 9
1/1/10 at 11:55pm
Thread Starter 
Good info! Yes, I do with the Beatles In Stereo was at a higher sampling rate... I wonder why they didn't at least do 48khz instead of 44.1? I know it is a minor difference.

I was just about to attempt the 24-bit conversion in dbpoweramp, thanks for saving me the trouble!
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post #4 of 9
1/2/10 at 12:21am
so 16bit flac -> alac with dbpoweramp is not an issue?
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post #5 of 9
1/2/10 at 12:25am
Thread Starter 
Quote:
Originally Posted by Bojamijams View Post
so 16bit flac -> alac with dbpoweramp is not an issue?
I did some conversions that seemed to be just fine. Just remember to download the optional codecs from dbpoweramp.
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post #6 of 9
1/2/10 at 2:15am
xrecodeII is another converter program you can check out.
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post #7 of 9
1/2/10 at 4:01am
Thread Starter 
I've heard that sample rates should be converted in equal multiples (i.e. 96k --> 48k; 88.2k --> 44.1k). Can anyone confirm this?
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post #8 of 9
1/2/10 at 4:30am
Thread Starter 
Is dbpoweramp's 24-bit limitation on the FLAC side, ALAC side, or a general 24-bit issue?
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post #9 of 9
1/3/10 at 2:08am
dbpoweramp has already released version 9 of the ALAC decoder/encoder and can now do 24-bit files.
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