Rockbox Xduoo X3
Jan 11, 2017 at 12:57 PM Post #1,231 of 2,617
Hi there,
 
In dire need of help! Something just isn't quite adding up with my xduoo x3 and rockbox!
 
I copy music across and then when I eject the device the folder that I've transferred appears to be there but contains no music! The folders remain and yet the music inside just disappears! I have show all files selected and I am showing hidden files/folders on my pc!
 
I am having to connect to my laptop out of rockbox mode as it doesn't recognize it otherwise and am copying music to the drive as opposed to the .rockbox folder.
 
Anyone experiencing anything similar?! I'm at my wit's end!
 
Jan 11, 2017 at 1:39 PM Post #1,232 of 2,617
Not experiencing your problem, but to help diagnose the issue can you tell us:
1) What operating system you are using to transfer the files
2) What you mean by "eject" the drive - if you mean "safely remove" in Windows, or umount + eject in Linux, make sure you are waiting for the message that says you can remove the device. A clue that this might be the problem would be extremely fast file transfers.
 
I'm also not entirely sure what you mean by connecting to the laptop out of rockbox mode... do you mean you have to boot into the original firmware to transfer files, or do you mean you can only transfer with rockbox and not the original firmware?
 
Jan 11, 2017 at 3:33 PM Post #1,233 of 2,617
I'm back!
I just watched a video on the Xduoo X3 with rockbox on it.
It's an mpeg file freely available here:
https://www.rockbox.org/wiki/PluginMpegplayer
I recorded the watching process to document my experience and to inspire others to do the same :) LOL
so here it is:
https://youtu.be/xo9mYQJrOSg
 
Will be back with another post explaining why exactly it's better to have a variable line output level which the official firmware does not provide but rockbox does. Prepare to be amased.
 
Jan 11, 2017 at 4:31 PM Post #1,234 of 2,617
Just showing everyone why you should think twice before getting the xduoo x3 dap.
Playing a 1khz sine wave file on both the official firmware and on rockbox, watching the output signal on the oscilloscope.
At max level the top of the sine wave is cut away, massively increasing thd (total harmonic distortion)
.
And on stock firmware there is a pitch problem, instead of producing a 1khz signal it produces a 990Hz signal. That's a 1% error at the output.
Using rockbox you can limit the max output to -1dB which should fix the clipping distortion,
Also in rockbox the slowing of the playback is fixed, in rockbox, file plays correctly (at the right pitch) by default.
Demonstrating the above on a digital oscilloscope.
 
P.S. even with the -1dB max limit you still get 8.5V peak to peak on the headphone out, which is a lot!
 
https://youtu.be/znWj93382SQ
 
Jan 11, 2017 at 5:41 PM Post #1,235 of 2,617
Thanks for testing and comparing the output of both the stock firmware and Rockbox. Looks like Rockbox is a requirement and not an option for the xDuoo X3. 
 
It would be interesting to see if this is an issue for all xDuoo DAPs, including the X2 and the X10.
 
Jan 11, 2017 at 5:56 PM Post #1,236 of 2,617
  Just showing everyone why you should think twice before getting the xduoo x3 dap.
Playing a 1khz sine wave file on both the official firmware and on rockbox, watching the output signal on the oscilloscope.
At max level the top of the sine wave is cut away, massively increasing thd (total harmonic distortion)

 
In rockbox this is expected for any positive gain.  0dB and below should not clip.  Is that what you see?
 
Jan 11, 2017 at 7:07 PM Post #1,238 of 2,617
  Just showing everyone why you should think twice before getting the xduoo x3 dap.
Playing a 1khz sine wave file on both the official firmware and on rockbox, watching the output signal on the oscilloscope.
At max level the top of the sine wave is cut away, massively increasing thd (total harmonic distortion)
.
And on stock firmware there is a pitch problem, instead of producing a 1khz signal it produces a 990Hz signal. That's a 1% error at the output.
Using rockbox you can limit the max output to -1dB which should fix the clipping distortion,
Also in rockbox the slowing of the playback is fixed, in rockbox, file plays correctly (at the right pitch) by default.
Demonstrating the above on a digital oscilloscope.
 
P.S. even with the -1dB max limit you still get 8.5V peak to peak on the headphone out, which is a lot!
 
https://youtu.be/znWj93382SQ

 
I think most of us are already aware that the X3's stock firmware plays 44.1 kHz files too slow.  That's a major reason why many of us installed Rockbox.  Cool to see it happen in your video, though.
 
The distortion is a surprise, but it only happens via headphone out with gain set to 99 or 100 percent.  Who the heck listens at that level, ever?  Most amplifier circuits begin to distort towards the limits of their operating range.  I normally listen at around -25 or -30 db.
 
Jan 11, 2017 at 7:57 PM Post #1,239 of 2,617
  Just showing everyone why you should think twice before getting the xduoo x3 dap.
Playing a 1khz sine wave file on both the official firmware and on rockbox, watching the output signal on the oscilloscope.
At max level the top of the sine wave is cut away, massively increasing thd (total harmonic distortion)
.
And on stock firmware there is a pitch problem, instead of producing a 1khz signal it produces a 990Hz signal. That's a 1% error at the output.
Using rockbox you can limit the max output to -1dB which should fix the clipping distortion,
Also in rockbox the slowing of the playback is fixed, in rockbox, file plays correctly (at the right pitch) by default.
Demonstrating the above on a digital oscilloscope.
 
P.S. even with the -1dB max limit you still get 8.5V peak to peak on the headphone out, which is a lot!
 
https://youtu.be/znWj93382SQ

 
Thanks for that.
 
It goes to show even though you have the same chipset, DAC and opamps if your power supply and other components are not up to scratch, it will degrade sound quality. It's the implementation that is important
 
Jan 11, 2017 at 9:51 PM Post #1,240 of 2,617
  His video shows that Rockbox also clips at 0dB .Ive  never had to turn my   Rockboxed X3 to max volume anyway tbh.Still interesting though.It would  not stop me recommending  the X3.

 
Then it sounds like the volume scale is off by one and it should be adjusted so that -1 dB is actually 0dB (or however much is needed so that 0dB is max gain).  
 
Jan 12, 2017 at 6:31 AM Post #1,241 of 2,617
guys, is there any way to force x3 to show the proper battery level on rockbox? in my case battery drains pretty fast to around 10-12% and then it can stay even for a few hours on that 10%... doesn't matter what value I put in battery capacity settings. 
 
Jan 12, 2017 at 10:22 AM Post #1,242 of 2,617
Still not got any response from the creator of this port regarding the voice files. Really frustrating.
 
There is just no manufacturer that produces an MP3 player for blind people. No money in it. And the Rockbox forums seem to have been down for ages - add to which the only devices they support are ancient piles of crap that aren't worth $2, let alone the time they put in to porting rockbox on them.
 
The only possibility is to try and find a Sansa clip+ and use that. Seems ridiculous that there is a new decent player which would be perfect for blind users... but that it can't be used as there is no one to fix the few remaining minor issues with the voice files.
 
Jan 12, 2017 at 10:52 AM Post #1,243 of 2,617
This drives me crazy too.  This issue, along with others probably wont get addressed until we get an official port in the works.
Rockbox on Xduoo X3 works pretty well, but understand, your mileage may vary at this point.
I'm going to peek at the code and see if I can add some simple printing of the battery setting to a log, to assure that it is really getting set.
I am suspecting that this issue not that the value does not get set, but maybe what the expected voltage or scale of the  battery is set to in the code (sadc-xduoo_x3.c)?
 
This Xduoo X3 and Rockbox are forcing me to learn how to program for it. Its very difficult for a novice like me  understand and contribute Rockbox, as I only have a basic understanding of C (from my Bash, Perl, PHP, BASIC experience)
 
 
FYI , I've taken my Xduoo X3 apart to see that battery,
My battery is labelled as:
E613773-2000mAh
 
160805 3.7v  7.4 wh
 
 

 
Jan 12, 2017 at 10:57 AM Post #1,244 of 2,617
  And the Rockbox forums seem to have been down for ages - add to which the only devices they support are ancient piles of crap that aren't worth $2, let alone the time they put in to porting rockbox on them.

 
The Rockbox forums do seem to be down now, but they were working yesterday, so that is hardly ages. I've got sympathy for your situation, but your anger towards rockbox and their developers seems misdirected. The developer of this port created it to scratch his own itch, and many of us are benefiting from that. Meanwhile, an official port for the chipset is underway by a rockbox developer that will hopefully address your problem and a few others with the port.
I don't know if you are a programmer yourself or not, if you are perhaps you can help with that.
 
Jan 12, 2017 at 11:04 AM Post #1,245 of 2,617
I must be unlucky. The rockbox forum has been down the last 3 different times I checked. Once before Xmas, once during, and today.

The rockbox people certainly don't deserve my anger. Its just frustration. The requirements for a blind person's mp3 are so basic that they can be served with 20 year old tech. But there is nothing out there.

Is someone working on an official port for the xduoo? That would be great. I'm guessing vortex has done the bulk of the heavy lifting already?

Unfortunately I am not a programmer. My skills in this regard are very limited.
 

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