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Rockbox for iBasso DX50 dual boot with stock firmware - Page 10

post #136 of 1976
Quote:
Originally Posted by ratinox View Post


Rockbox will down-sample to 16/44.1 before feeding bits to the DAC. Now go read post 10362330.

 

This is a bit oversimplified.  Rockbox has to have a fixed output sampling rate, which is configurable (44.1k or 48k if you use Opus a lot).  Internally, all of the rockbox code uses 32 bit samples (ARM processors are 32 bit so using anything else wouldn't be efficient).  What gets passed to the DAC is whatever the audio driver decides to pass (it actually can take 32 bit samples if it wants).

 

I discussed this with the DX50 developer, and told him to test 24 bit output and see if the hardware actually support it.  Basically any modern DAC will happily accept 24 or even 32 bit samples, but most do not actually use the extra information, so you have to test and see what comes out.  If it can actually produce a different output voltage when you change the 17 bit in an audio sample, then it will be simple to support 24 bit output.  If changing the 17th bit does nothing, then I suggested he use 16 bit output to save battery life.  Most likely though the port will eventually support whatever the hardware is actually capable of.  

post #137 of 1976

update available! fixes backlight (amongst other things)

post #138 of 1976
Quote:
Originally Posted by saratoga View Post
 

 

This is a bit oversimplified.  Rockbox has to have a fixed output sampling rate, which is configurable (44.1k or 48k if you use Opus a lot).  Internally, all of the rockbox code uses 32 bit samples (ARM processors are 32 bit so using anything else wouldn't be efficient).  What gets passed to the DAC is whatever the audio driver decides to pass (it actually can take 32 bit samples if it wants).

 

I discussed this with the DX50 developer, and told him to test 24 bit output and see if the hardware actually support it.  Basically any modern DAC will happily accept 24 or even 32 bit samples, but most do not actually use the extra information, so you have to test and see what comes out.  If it can actually produce a different output voltage when you change the 17 bit in an audio sample, then it will be simple to support 24 bit output.  If changing the 17th bit does nothing, then I suggested he use 16 bit output to save battery life.  Most likely though the port will eventually support whatever the hardware is actually capable of.  

 

Wow! Glad to see you here! Thank you for attention to the port :)

Actually I've done some preliminary measurements with RMAA as you suggested.

In short

1) my 'fast track ultra' card actually gives around -102dB SNR and DR in 24/96 mode in a loop, so *almost* enough to measure >16 bit

2) dx50 with mango player goes as close to card loop quality as possible, sometimes even 0.1dB better =D

3) dx50 with rockbox shows around 2-3 dB worse

 

BUT that's very preliminary, I have to verify everything and find a proper cable.

 

By the way, I've started searching places in code which I have to change for 16->24/32, but did'nt spend much time on that yet.

 

 

Taking the opportunity to talk, let me present the new build where 2 most annoying things (backlight off and power button) look like fixed:

https://bitbucket.org/isergachev/rockbox/wiki/Home

post #139 of 1976
post #140 of 1976

Are you still using the Android port as a base?  I'm actually not too familiar with that, so you might need to ask Kugel.  The rockbox PCM/DSP engine though is already pure 32 bit.  Its possible the Android bits assume 16 bit, though thats probably not too hard to fix.  Most likely at some point its just calling the functions in dsp_sample_output.c, which could easily be made to clip to 24 bit instead of clip to 16 as now.  

post #141 of 1976
Quote:
Originally Posted by xzcc View Post
 

Also, please report issues here:

https://bitbucket.org/isergachev/rockbox/issues?status=new&status=open

 

screen off(after time out) works now although it still doesn't work with the power button, but I guess it's working as intended?

post #142 of 1976
Quote:
Originally Posted by saratoga View Post

This is a bit oversimplified.

No argument there. A full explanation would fill a small text book and I'm not qualified to write it. smily_headphones1.gif
post #143 of 1976
Quote:
Originally Posted by davtse View Post
 

 

screen off(after time out) works now although it still doesn't work with the power button, but I guess it's working as intended?

Just because I thought that 'back' action is needed more that 'screen off'.

You are free to suggest the best keymap for dx50 and I'll try to implement it.

post #144 of 1976
Quote:
Originally Posted by xzcc View Post
 

Just because I thought that 'back' action is needed more that 'screen off'.

You are free to suggest the best keymap for dx50 and I'll try to implement it.

 

I think your implementation is fine, although those who don't use the hold switch might find the screen off button more useful.

post #145 of 1976
Quote:
Originally Posted by xzcc View Post




Taking the opportunity to talk, let me present the new build where 2 most annoying things (backlight off and power button) look like fixed:
https://bitbucket.org/isergachev/rockbox/wiki/Home

Great job many many thanks. With dual boot - it is a no brainer to instal, which I have done biggrin.gif

Is it my ears or does rockbox sound cleaner & better than the Ibasso FW 2.8 and if so why ??
post #146 of 1976

So I installed it )
Number of possibilities is astounding.
Very unusual ) are unusual and new opportunities and a lack of old annoying bugs )
Will need to get used to the interface logic , as well as figure out how to upload there another theme ...
Unusual sound manner . Now clearly felt evenness of sound, but to me it seems more like the old ) have a reason to play with the equalizer.
Annoying oversampling course topic , but luckily for me , in my library 99% of records are 16/44, as 24/192 only 3 of digitizing vinyl with Pink Floyd ) In general, many thanks for your work !) If you cat disable the oversampling it will be all cool !

post #147 of 1976

Great with those fixes it is really good!

Do you saw some low level settings on android that can improve things (clock / jitter) or WM8740 settings (filter slow/fast, ...)

post #148 of 1976
Thread Starter 
Quote:
Originally Posted by highfell View Post



Great job many many thanks. With dual boot - it is a no brainer to instal, which I have done biggrin.gif



Is it my ears or does rockbox sound cleaner & better than the Ibasso FW 2.8 and if so why ??

 



That is because RB by default has a flat signal response. This goes to show the iBasso firmware is a bit colored. If you like the original FW you can still achive it with RB by playing with the EQ function. But I like the sound RB default brings out on DX50. It lifts every ounce of details in the music a feeds it raw to your amp and headphone. Making the overall source more natural than the default FW (imo).
post #149 of 1976

To the Rockbox team... this is so cool! Love it.

 

Question: Is it possible to save the time and date? I know std FW lacks it and assume there is no clock in the device. Is that why the date and time doesn't stick?

post #150 of 1976
Quote:
Originally Posted by Jpfe8851 View Post
 

To the Rockbox team... this is so cool! Love it.

 

Question: Is it possible to save the time and date? I know std FW lacks it and assume there is no clock in the device. Is that why the date and time doesn't stick?

+1!  Also, I'm a complete n00b to RockBox's control UI.  Is there a guide to the settings somewhere?  I did manage to get it playing and I do like what I hear!:biggrin:

 

Cheers!:beerchug:

-HK sends

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