Really bad resampling of 44.1kHz/16bits files with Fixed Resoultion SPDIF setting

Here the answer for anybody asking if this can be heard.

These are the original files (yes, you will very likely hear absolutely nothing):
44kHz/16bits: CCIF_19k_20k_1_1_-6_dBFS_44k_PCM16_LR.flac
48kHz/16bits: CCIF_19k_20k_1_1_-6_dBFS_48k_PCM16_LR.flac

And the are the results:
44kHz/16bits to 192kHz/24bits: 44b16to192b24.flac
48kHz/16bits to 44.1kHz/16bits: 48b16to44b16.flac

While when the resampling works as expected (again, you will most probably not hear anything):
48kHz/24bits to 44.1kHz/16bits: 48b24to44b16.flac
 
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It reminds me a bit of old stories of "wiim and his deceitful drc"...
" povre wiim et son fourbe drc"
;-))
 
erazortt said:
While at 16 bit inputs, non-integer conversions of the input sampling rate to the output sampling rate will produce a bad result.
Click to expand...
Your observations regarding non integer conversion are similar to mine.

O

Post in thread 'Advantages of using Fixed resolution?'

WiiM Support said:
Hi onlyoneme,

The bit resolution issue has been fixed, and we have whitelisted the update for your device. Could you please test it and let us know if it resolves your streaming issue? Thank you for your assistance and support.
Click to expand...
I've made some tests and it's fixed indeed, I do not observe a bit depth degradation. Well done.

However I have some remarks:

1. Resampling results differ a bit when the toslink input is used and when we use a network streaming, especially for upsampling.

That's the sine 1 kHz signal at 0 dBFS, network streaming, 48>96 upsampling:

1721038875289.png

and the...
  • Like
 
onlyoneme said:
Your observations regarding non integer conversion are similar to mine.

O

Post in thread 'Advantages of using Fixed resolution?'

WiiM Support said:
Hi onlyoneme,

The bit resolution issue has been fixed, and we have whitelisted the update for your device. Could you please test it and let us know if it resolves your streaming issue? Thank you for your assistance and support.
Click to expand...
I've made some tests and it's fixed indeed, I do not observe a bit depth degradation. Well done.

However I have some remarks:

1. Resampling results differ a bit when the toslink input is used and when we use a network streaming, especially for upsampling.

That's the sine 1 kHz signal at 0 dBFS, network streaming, 48>96 upsampling:

1721038875289.png

and the...
  • Like
Click to expand...
Have you compared WiiM resampling to sox?
 
I love music, but I have to resample somewhere. For now the task is handed over to my downstream MiniDSP Flex Eight, and I am quite ashamed that I didn’t catch the earlier measurements by @onlyoneme…
 
Upsampling music would just muddy the sound. Still useful for those who needs them. I personally don’t like it.
 
Smartplug said:
Is it even audible? Measurement can show this information but what matters if it’s audible. We get excited when we see thd+noise .011 vs .0011. It’s nice to see many zero before number. Many in blind test wound not able to tell difference unless your ear is precision audio.
Click to expand...
Yes its audible and I noticed this several weeks ago .
M

Post in thread 'Does wiim reclocking in DDC mode?'

s3igell said:
Wiim offers as a setting "Fixed Frequency" Output on the Digital Outputs. If that is not desired, turn it Off.
Click to expand...
Yes, and the sound gets slightly worse using this fixed option, a bit thinner and harder at least with my ears.

The fixed sample rate option in the ultra is better sounding than a Yamaha wxc50 resampling ( which is terrible in preamp mode ) , but the Ultra sounds best with native sampling frequency on all material.

With fixed resolution enabled, the sound is slightly thinner and sound less ”real”.
 
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So, in the meantime I have tested the optical output of the Wiim Ultra directly, and not on the analog outputs of my external DAC. I tested all combinations of sampling rates and bitdepths, below are just the respresentative ones.
The summary remains as identified before:
- 24 bits in the input will always resample correctly independently of the output setting
- 16 bits inputs are not correctly resampled when the resmpling is non-integer

44k/16b to 48k/16b: not ok
44k16bTo48k16b.png

44k/16b to 48k/24b: not ok
44k16bTo48k24b.png

44k/24b to 48k/16b: ok
44k24bTo48k16b.png


44k/24b to 48k/24b: ok
44k24bTo48k24b.png

48k/16b to 44k/16b:
48k16bTo44k16b.png

48k/16b to 44k/24b:
48k16bTo44k24b.png

48k/24b to 44k/16b:
48k24bTo44k16b.png

48k/24b to 44k/24b:
48k24bTo48k24b.png
 
Hi Team,

Thank you for your detailed summary! Our team is actively investigating this issue and working on a solution. We plan to address it in the next version, so please stay tuned for updates. Your patience and feedback are greatly appreciated!
 
(It might be useful to check the general behavior in 16bit even without resampling.....
as a precaution)
 
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canard said:
(It might be useful to check the general behavior in 16bit even without resampling.....
as a precaution)
Click to expand...
Valentino said:
Well spotted @canard.
Did you look at 16/44.1 straight through, @erazortt?
Click to expand...
slartibartfast said:
In the first post transcoding 48kHz 16bit to 192kHz 24 bit is fine. The issue only seems to be with non integer resampling.
Click to expand...

I have tested all combinations, here is a link to a folder containing them all:
link to all combinations

But as a preview, thats the image for 44/16 to 44/16:
44k16bTo44k16b.png
There are spikes, yes, but those extend to less then -100db, so that is fine for 16bits, since here we assume the noise floor to be at -96db.

For 44/24 to 44/24 the image looks like that:
44k24bTo44k24b.png
 
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