Rockbox Technical Forums

Support and General Use => Recording => Topic started by: Shindig on February 02, 2007, 03:25:33 PM

Title: 48KHz Hardware?
Post by: Shindig on February 02, 2007, 03:25:33 PM
Setting aside space and IC to PCB fit limitations, what kind of hardware modification is required to allow for analog 16bit 48KHz recording on the H120/H140?

 
Title: Re: 48KHz Hardware?
Post by: Multiplex on February 03, 2007, 06:04:25 AM
You should do a search but I seem to rememebr that the 44.1kHz limit is the hardware (there are links to the datasheets on the Wiki) and 48kHz is already supported (probably needs the REP patch) for the Digital input.
Title: Re: 48KHz Hardware?
Post by: Shindig on February 03, 2007, 03:52:25 PM

You should do a search but I seem to rememebr that the 44.1kHz limit is the hardware


I know, that's why I asked what kind of hardward modification is required to allow for 48KHz recording.

48kHz is already supported (probably needs the REP patch) for the Digital input.


Again, If you read my question carefully, you'll notice that I asked about analog recording. I know it can record 48KHz through digital in.


Title: Re: 48KHz Hardware?
Post by: saratoga on February 03, 2007, 06:09:18 PM
Skimming the data sheet, it looks like you'd need to provide a different clock signal for the chip.  There are two clock inputs possible, and software register to switch between them.  Might want to look at the wiring diagrams on the wiki and see if the other clock pin can be accessed.  Ignoring the difficultly in doing this, you might be able to provide another clock signal for 48khz.

Can I ask why you want this though?  Theres no meaningful advantage to 48KHz, and if you need it for compatibility with other software, there are fast and extremely high quality resamplers available.  IMO a mod like this is a solution in search of a problem.
Title: Re: 48KHz Hardware?
Post by: catstevecam on February 03, 2007, 07:55:20 PM
Have to aggree with Saratoga - to resample using existing software is so much more straightforward than selecting the hardware route - unless you really have the time for the extra challenge.

Thanks to the developers and Mmmm for the latest H120/140 recording build - I have only recorded 2 weekend sessions so far - but the quality, and control, and being able to record directly as wav has been wonderful - thank you ROCKbox.

Steve
H120 and Recorder 20
Title: Re: 48KHz Hardware?
Post by: Multiplex on February 04, 2007, 04:14:34 AM
Sorry Shindig, I'd obviously been reading too many queries from folks in other topics who hadn't done any checking and skim read your post.

The datasheet Saratoga references is in the Wiki

I believe that there are some comments round here from folks using external ADCs which offer greater quality and possibly 48kHz - I think some of them are pretty small and portable - though not obviosly internal. Several devices are mentioned in the thread about 20bit recording.