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Toggle playback sample rate iriver H100 H300?

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saratoga:
Bad resampling introduces distortion, but generally preserves pitch.   You can see that in the images you posted where the 10khz tone continues to be 10khz. 

Its not generally possible to determine that audio is not being resampled by listening to it, so my assumption would be that they're also resampling.  You're welcome to investigate this however. 

Julian67:
Yes, I did note that the original 10000 Hz tone is still present but also that other audible tones are introduced (the distortion you mention) so the overall pitch is not preserved.  The difference is as easy to hear as it is to see in those images.

So accepting that that the iRiver original firmware is performing SRC (because the hardware is incapable of supporting 48KHz due to the XTAL rate) then Rockbox's sample rate converter is performing much worse than the OF's.  Playing back non-44.1KHz files in Rockbox introduces tonal change while no such change is heard when using the OF.  But I can't help feeling almost totally sceptical that iRiver over ten years ago achieved on very low power devices the kind of high quality SRC that would have been too demanding to be practical on most desktop CPUs of the time.

What looks more likely is that Rockbox's (linear?) SRC is performing much the same as any other default (bad but fast and it will work) SRC as found on any number of devices and operating systems, while iRiver OF is playing back at native sample rates exactly as claimed.  As you can tell I'm no engineer but this second scenario seems normal while the first requires iRiver to have achieved something extraordinary, still unmatched by anyone else, for this to have passed completely unnoticed, and for them to have decided to mislead their users for several years instead of exploiting their potentially lucrative miracle breakthrough.

saratoga:
Newer versions of Rockbox actually use cubic hermite rather than linear.

Removing aliasing from high frequency pure tones when resampling is actually quite easy/fast.  I didn't bother implementing it yet because it doesn't help with real music. 

Julian67:
Thank you very much for your explanations and information, and patience.  I am about to fly to S. Korea to find the guy who wrote the iRiver H100 manuals and encourage him to enjoy the left overs of the crow I am currently eating.

I'm surprised (but probably shouldn't be) that iRiver could be so misleading in the way they present the product info and that they did so more than once.  In the H140 manual their info on the supported sample rates is in places inaccurate and misleading while in the H340 manual it varies between vague and absent.

btw in the searching and reading I've been doing I did actually find one person who soldered a different crystal to the board of his H140 to reclock it....

Is Rockbox using either of the Speex or SoX sample rate converters?  Something else?

saratoga:

--- Quote from: Julian67 on July 22, 2013, 11:25:17 AM ---I'm surprised (but probably shouldn't be) that iRiver could be so misleading in the way they present the product info and that they did so more than once.  In the H140 manual their info on the supported sample rates is in places inaccurate and misleading while in the H340 manual it varies between vague and absent.
--- End quote ---


--- Quote from: Julian67 on July 22, 2013, 11:25:17 AM ---Is Rockbox using either of the Speex or SoX sample rate converters?  Something else?

--- End quote ---

Its a custom one that jhMikeS and I wrote. 

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