[utkuozdemir]

Hello everyone, this is my first post.
 
I have an Ipod classic 6th generation 1st revision (120gb) for about one year. I'm planning to buy ultimate ears triplefi 10 earphones soon, so I'm getting some of my music with high quality, like vinyl rips (flac), then convert them to apple lossless. These rips often come with 24bit/96khz quality. Unfortunately ipod classic cannot play music with sample quality over 48khz, so when I make the convertion (using dbpoweramp and its downsample dsp effect), I downsample these music to 48khz. Finally I get 24bit/48khz apple lossless music, playable in my ipod.
 
But I heard somewhere it is possible that Ipod does an internal downsampling and play them as 16bit/44khz. Is it true, where can I find exact information about that?
It seems I got 3 options:
1- Downsample them to 48khz, keep bitrate as 24, and play on ipod. (which I already do)
2- Downsample to 44khz and change bit depth to fixed 16bit using dither or not (I don't know what dither means btw)
3- Try to find cd rips or rip my own cds with original 24bit / 44khz quality (not a preferred option because I really prefer the masterings of vinyls and their rips are generally 24/96)
 
What would you suggest? Do you know if there's an internal resampling in ipod's OS or not?
 
One more question: Dou you think I should use ipod's equalizer (rock mode) when listening to classic rock music?
 
 
If you have any other suggestions, I'd be glad to hear them. I'm new at this stuff.
 
 
And sorry for bad English.
 
 
 
 
 
 

 

[Brent Hutto]

The iPod will only play and accept 44.1KHz/16-bit music files. If you're downloading something at other than those specifications then it must be iTunes or some other software that is doing the downconvert. Not the iPod itself.

In general, you want to know where you music is getting upconverted or downconverted and make sure that only happens (at most) one time. You definitely don't want it downconverted several times at different points in the process.

 

[utkuozdemir]

Interesting. That means itunes can convert 48khz to 44.1khz but cannot convert 96khz to 44.1 on sync process, which does not make much sense to me. And after sync, I looked the properties of the file in ipod, and it was still shown as 24/48. If it's not in ipod itself, where does it happen?
 
If you are sure, that means I also need to downconvert bit rate to fixed 16bit? If so should I apply dither, and if so which one (triangular, rectangle)? 

 

[Brent Hutto]

Well won't claim metaphysical certainty that an iPod will only play 16-bit files but I would be totally gobsmacked to find out I'm mistaken.

OTOH, I would not find it suprising at all that iTunes reports the format of the file as stored in iTunes rather than as stored on the iPod itself.

Perhaps someone with more comprehensive knowledge of these things will step in and settle the issue.

P.S. In the screenshot, you are showing the "Summary" tab. I believe if you click on the adjacent "Info" tab you'll see among other thing the file name of the file as stored on your computer. This wouldl confirm that you're just seeing the iTunes file properties, nothing to do with what's on the iPod...

 

[Skylab]

The iPod will absolutely handle 48 kHz for sure.  I have my iPod connected to the Wadia i170 and then to an Assemblage jitter filter, and that shows the sample rate.  When I play 48 kHz files on the iPod, the 48 kHz light comes on on the Assemblage.
 
I'm not sure about the bit rate though.

 

[elfary]

I read a while back on Stereophile that the iPod played 48-24 files BUT (and it's a huge but here) truncating on the fly to 16 bits. This matches my experience with my iPods the take and play 48-24 ALAC files but truncating (not even dithering) them.

 

[utkuozdemir]

I agree with Skylab, thought you couyld be right so I found the file inside ipod on linux, and compared it with original file. itunes only renames them, they have exactly same bit depth and sample rate. So, if there's no converting in ipod itself, we can say iPod handles maximum 24bit/48khz quality audio. Here I'm putting a screenshot of the file in ipod (unfortunately I couldn't find out the bit depth of alac file under linux, so looked it under windows).
Question is, is there an internal convertion?

 

[elfary]

That's what i was trying to point out. According to a long thread at stereophile discussing this the common agreement was that iPods do truncate the 24 bits to 16. Thus they just drop 8 bits without dithering so some nasty distortion happens at the low level sounds.

 

[Skylab]

Yeah I have only put 48/16 onto my iPod, since I don't believe that the extra bits would be worth the larger file sizes...already using lossless, so the files are big as they are.

 

[utkuozdemir]

Understood. Here the last answer says that there's a big difference between 16bit and 24bit files on ipod, but he is using ipod touch, I don't know if it's same with ipod classic. He also says that:
 
Quote:

Why do I downsample to 48KHz and not 44.1? -- think about it: 48 is half of 96, and 44.1 is not. Half the sampling rate means that (thinking about it in movie terms) every other frame is used without any interpolation (and therefore further degredation) of the original. I have seen 24bit/88.2KHz studio master files for sale on some audiophile websites. I haven't tried one yet, so I don't know if these work on an iPod without down-sampling, but again, the answer for me will be to down-sample to 44.1KHz and not 48KHz.

 
Does it make sense, should I prefer converting 96khz files to 44.1 rather than 48khz? And about dithering, triangular or rectangular dithering, which is better?

 

[Skylab]

It is mathematically simpler to go from 96 to 48 for sure, and so it does have the potential to sound better than going to 44.1, yes.  Some people are mastering at 88.2 kHz, just because they believe it sounds better when downsampled to 44.1.  I personally always go to 48 from 96, not to 44.1.

 

[utkuozdemir]

Thank you all for your replies. An iPod owner with 16000 posts here should have good choices. What do you say about dither, do you use it an how?

 

[Skylab]

I don't dictate that - I am using dBPoweramp to downres from 96 to 48.  I'm not 100% sure what algorithm they are using for the sample rate conversion, but the results seem good to me.

 

[utkuozdemir]

I meant bit depth convertion, not sample rate. We're OK with sample rate, but if ipod truncates 8 bits from 24bit audio, it's better to change bit depth on pc, and there's an option called dither with 2 choices, rectangular and triangular. I'm asking which one is better?

 

[Skylab]

I personally cannot answer that question.