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Ipod classic - rockbox - its happening. - Page 186

post #2776 of 3594
Quote:
Originally Posted by Hellkitchen View Post

Thanks for reply. I must admit that I'm quite impressed about ipod classic SQ. I've decided to give him a try with original Apple's firmware.. I really like itunes library management and features like genius.
Maybe I say so because I've never try RockBox on any Apple's device...

Will be the SQ so much improved over original firmware?

 

Well, that's debatable. First of all, the hardware is still the same.

If you have a European Classic, the volume limiter will be removed thanks to Rockbox. That's how I noticed what my earplugs actually could sound like with the proper power :) To me Rockbox without any adjustments already sounds better than OF, but this could very well be the placebo effect. The major benefit of Rockbox is that you can adjust the sound and equalizer very precisely to your own needs.

 

Has anyone here messed around with the Compressor treshold? Standard value is -3dB, but I like the sound better when it's at -12dB:) 


Edited by r100 - 11/2/13 at 2:33pm
post #2777 of 3594

Quick question. Can't seem to find the answer anywhere. But I just reinstalled this on my iPod Classic 6g 80gb. Would it now be able to playback lossless 24-bit/96khz files? Or would it downsample it to something smaller. I think I read somewhere that it has a 48khz sample rate limit, but I'm not all too sure about it. And if so, what would be the maximum resolution that it could handle without having to downsample?

 

Additionally, I'm still using an emCore r859 build along with the latest rockbox build from the daily builds. And, as with the others can't get a stable usb connection after a few dozen retries. Would it be recommended that I update my emCore to r880 like most others did? It seems to have fixed their usb connection problem.


Edited by christianabiera - 11/3/13 at 5:47am
post #2778 of 3594
Quote:
Originally Posted by christianabiera View Post
 

Quick question. Can't seem to find the answer anywhere. But I just reinstalled this on my iPod Classic 6g 80gb. Would it now be able to playback lossless 24-bit/96khz files? Or would it downsample it to something smaller. I think I read somewhere that it has a 48khz sample rate limit, but I'm not all too sure about it. And if so, what would be the maximum resolution that it could handle without having to downsample?

 

Additionally, I'm still using an emCore r859 build along with the latest rockbox build from the daily builds. And, as with the others can't get a stable usb connection after a few dozen retries. Would it be recommended that I update my emCore to r880 like most others did? It seems to have fixed their usb connection problem.

 

You're limited by the DAC in the iPod, and the lack of ability to output audio via USB to an external DAC with greater capabilities.  So yeah, 44.1 or 48 kHz, depending on how you set it up.  And 16-bit, of course.  I haven't bothered trying, so I don't know if it would downsample 24/96, for example.  But I'd bet my house it would sound like crap.  Having Sound Forge Pro, I'd downsample and dither such files myself, if I only had a 24/96 copy.  I'm sure even Audacity would produce far better results than letting the iPod do it, assuming it can.

 

re: emCORE, I doubt it would hurt, and might help.  There are quite a few versions you could try.  I just decided to try to latest, and it proved stable.  Prior to that I was running r868 and r866.  With those, I often had to hard reset (Menu + Select) the iPod after connecting it and not getting a response.  Hard reset always worked, but a bit of a PITA.


Edited by ThurstonX - 11/3/13 at 6:43am
post #2779 of 3594

Are you sure it's not 24/48?

I always thought the hardware is: http://www.cirrus.com/en/pubs/proDatasheet/CS42L55_F1.pdf

Not sure what the Rockbox limitations are though..

 

Edit: And this was merged last summer: http://gerrit.rockbox.org/r/#/c/304/


Edited by r100 - 11/3/13 at 2:14pm
post #2780 of 3594
Quote:
Originally Posted by r100 View Post
 

Are you sure it's not 24/48?

I always thought the hardware is: http://www.cirrus.com/en/pubs/proDatasheet/CS42L55_F1.pdf

Not sure what the Rockbox limitations are though..

 

No, definitely not sure.  If it will do 24/48, that's pretty good.

post #2781 of 3594
Rockbox will play 24/48 and 24/96 files from personal experience but not sure on whether it makes use of the extended bit depth.
post #2782 of 3594
Quote:
Originally Posted by jazzman7 View Post

Rockbox will play 24/48 and 24/96 files from personal experience but not sure on whether it makes use of the extended bit depth.

Rockbox will output max 16/48.  That's CD quality which is still 4-5x's better than 256 MP3's.

 

The Rockbox will accept 24/48 max but can only output at 16/48 max.  That's the restriction of the iPod DAC.

post #2783 of 3594

Well, CD quality is actually 16-bit/44.1 KHz.

 

And according to FreemyiPod the DAC for the Classic (all generations) is a CS42L55, which is able to do 24/48: http://freemyipod.org/wiki/Hardware

 

"The CS42L55 is a highly integrated, 24-bit, ultra-low power stereo CODEC based on multi-bit delta-sigma modulation. Both the ADC and DAC offer many features suitable for low power portable system applications."

 

SYSTEM FEATURES
-High Performance 24-bit Converters
-Flexible Clocking Options: 8.000, 11.029, 12.000, 16.000, 22.059, 24.000, 32.000, 44.118 and 48.000 kHz Sample Rates
post #2784 of 3594

The DAC will accept 24 bit samples, but IIRC when we tried putting it in that mode the audio quality was identical, so it made more sense to save power and just feed it 16 bit samples.  I think the real-world effective number of bits is more like 15 or so.  IMO that makes it a 16 (or 15) bit DAC, even if they want to be clever and accept 24 bit data. 

 

You can configure the sample rate to 44.1k or 48k.  

post #2785 of 3594
Quote:
Originally Posted by r100 View Post
 

Well, CD quality is actually 16-bit/44.1 KHz.

 

CD quality can be 16/44 or 16/48, depends on the artist, The Killers released all their CD's in 16/48, most artists opt for 16/44.

post #2786 of 3594
Quote:
Originally Posted by RUMAY408 View Post
 

CD quality can be 16/44 or 16/48, depends on the artist, The Killers released all their CD's in 16/48, most artists opt for 16/44.

 

Cool, didn't know that! Always thought the Red Book was very strict on that.

post #2787 of 3594
Quote:
Originally Posted by RUMAY408 View Post
 

CD quality can be 16/44 or 16/48, depends on the artist, The Killers released all their CD's in 16/48, most artists opt for 16/44.

For what is a 16/48 worth? It won't play in a cd player... (red book rules) moreover will there be an audible differences in a genre that has a dynamic range of 30-40 dB?. BTW: my The Killers cd is 16/41. Less then 8% of sample rate gain is nonsense if you have to resample to lower rates!!

post #2788 of 3594
Quote:
Originally Posted by momom View Post
 

For what is a 16/48 worth? It won't play in a cd player... (red book rules) moreover will there be an audible differences in a genre that has a dynamic range of 30-40 dB?. BTW: my The Killers cd is 16/41. Less then 8% of sample rate gain is nonsense if you have to resample to lower rates!!

Frequency rates iTunes, Mac and on my DAC as 16/48 so beg to differ.  Agreed not much difference between 16/44 and 16/48.

 

I have spent countless hours on this ridiculous topic Trolldragon originally straightened me out on what an iPod can and can't do.  Went so far as to go to the Wolfson DAC schematics originally sent and processed by Apple for the iPod.  So 24 bit can be inserted on the iPod but only played out at 16 bit.  The Rockbox engineers have outlined in detail what the iPod can and can't do. 16/48 is maximum output.  

 

If you have high resolution audio or download a vinyl track to 24/96 you can use XLD software (free and amazing) to compress to a divisible audio sample you can use ex. 24/96>16/48 or 24/88>16/44  to output on the iPod. 

 

You can go crazy with the high res with the right audio equipment the sky seems to be the limit now, 24/172 and above.

post #2789 of 3594
Quote:
Originally Posted by RUMAY408 View Post
 

Frequency rates iTunes, Mac and on my DAC as 16/48 so beg to differ.

 

Offtopic: Then I guess we misunderstood, you referred to CD-like quality and how Apple qualifies and names this. I was referring to the actual Compact Disc Digital Audio, defined with the Red Book from 1980, based on the Nyquist sampling theorem.


Edited by r100 - 11/6/13 at 2:18am
post #2790 of 3594
Quote:
Originally Posted by r100 View Post
 

 

Offtopic: Then I guess we misunderstood, you referred to CD-like quality and how Apple qualifies and names this. I was referring to the actual Compact Disc Digital Audio, defined with the Red Book from 1980, based on the Nyquist sampling theorem.

I think I was caught up with the semantics of iPod vs CD sample rates. :ksc75smile:

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