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Xduoo x3

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RomanB:
Also there is still problem with 192kHz (also 176,4kHz) files. Some of them are skip, some of them „only“ crackle, and sometime xDuoo X3 use complete to freeze.  Maybe if there is not posible alocate more memory (or other necesseary sources), would by better switch them automaticaly to 96 or 88kHz (if I swith frequency manualy then crackle is away, but skiping fiels are still skipping).

saratoga:

--- Quote from: RomanB on October 16, 2020, 04:32:39 AM ---I have one more question. How it is with hi-res 24bit files. Are they converted to 16bit before sending to DAC or full path is 24 bit?

--- End quote ---

Decoding is done at 32 bit precision but everything is dithered down to 16 bit for playback because we never had a device that could actually play back the 17bit or greater above the noise floor. Adding support for this would be neat, but would make little difference in practice.


--- Quote from: RomanB on October 16, 2020, 04:53:34 AM ---Also there is still problem with 192kHz (also 176,4kHz) files. Some of them are skip, some of them „only“ crackle, and sometime xDuoo X3 use complete to freeze. 

--- End quote ---

Depending on the format, the CPU is probably not fast enough to decide those files, respect on MIPS where there are few cosec optimizations. The test_codec tool can be used to benchmark codecs, although it forces you to compile your own build.

johnb:
I confirm the crackle @ 192kHz. I checked the Buffering Thread in the debug menu. The bar is always >= 95%, i.e. constantly refilling. I suppose this is what keeps the device too busy.

Edit: the X3 only shows PCM (which for the X3ii also is always close to 100%).
The other two bars in the X3ii are not shown for X3.

Edit2: Not that I care too much about such sampling rates ...

speachy:

--- Quote from: RomanB on October 16, 2020, 04:53:34 AM ---Also there is still problem with 192kHz (also 176,4kHz) files. Some of them are skip, some of them „only“ crackle, and sometime xDuoo X3 use complete to freeze.  Maybe if there is not posible alocate more memory (or other necesseary sources), would by better switch them automaticaly to 96 or 88kHz (if I swith frequency manualy then crackle is away, but skiping fiels are still skipping).

--- End quote ---

The reason for the "crackle" at higher data rates is that the the X3 can't keep the audio codec fed under high loads -- by the time we are able to start servicing the interrupt that tells us the audio buffer needs more data, it's already too late.

(Basically, we need double-buffered DMA at the hardware level, and the DMA controller in the jz4760 does _not_ support this.. but their newer SoCs do.  There are some other games we can still try to work around this but they all require a significant rework of the low level asm interrupt handling)

RomanB:
Hallo
I would like to ask if bootloader are the same like Vortext version or if it is new one. I noticed in „major changes“ these sentence: „2021-08-26: xduoox3: Disable bootloader USB mode entirely, Bootloader improvements“. But the rockbox utility (1.5.1 and 1.5.0) shut down (without any error message) after I try install bootloader.  I think that it is the same problem like in this article: https://www.reddit.com/r/rockbox/comments/10quizp/help_installing_on_xduoo_x3/

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